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Technical Committee C.3.3 Road Tunnel Operations of the World Road Association

www.piarc.org

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FIXED FIRE FIGHTING SYSTEMS IN ROAD TUNNELS: CURRENT PRACTICES AND RECOMMENDATIONS

STATEMENTSThe World Road Association (PIARC) is a nonprofit organisation established in 1909 to improve international co-operation and to foster progress in the field of roads and road transport.

The study that is the subject of this report was defined in the PIARC Strategic Plan 2012 – 2015 and approved by the Council of the World Road Association, whose members are representatives of the member national governments. The members of the Technical Committee responsible for this report were nominated by the member national governments for their special competences.

Any opinions, findings, conclusions and recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of their parent organisations or agencies.

This report is available from the internet site of the World Road Association (PIARC) http://www.piarc.org

Copyright by the World Road Association. All rights reserved.

World Road Association (PIARC)Tour Pascal B - 19e étage92055 La Défense cedex, FRANCE

International Standard Book Number 978-2-84060-375-7Frontcover © Marina Coastal Expressway, Singapore

Technical Committee 3.3 Road Tunnel Operations of the World Road Association

FIXED FIRE FIGHTING SYSTEMS IN ROAD TUNNELS: CURRENT PRACTICES AND RECOMMENDATIONS

FIXED FIRE FIGHTING SYSTEMS IN ROAD TUNNELS…2016R06EN EXECUTIVE SUMMARYFIXED FIRE FIGHTING SYSTEMS

IN ROAD TUNNELS: CURRENT PRACTICES AND RECOMMENDATIONS

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AUTHORS/ACKNOWLEDGMENTSThis report has been prepared by Working Group 4 of the Technical Committee 3.3 of the World Road Association (PIARC).

The contributors to the preparation of this report are:

• Radim Bajger (Czech Republic)• Matthew Bilson (Australia)• Grzegorz Blaszczyk (Poland)• Rune Brandt (Sweden / Switzerland)• Lionel Brown (UK)• Harald Buvik (Norway)• Ricky Carvel (UK)• Gary Clark (UK)• Bruce Dandie (Australia)• Ignacio Del Rey (Spain)• Arnold Dix (Australia)• Leslie Fielding (UK)• Sylvain Garnier (France)• Robin Hall (UK)

• Norris Harvey (USA)• Haukur Ingason (Sweden)• Marko Jarvinen (Finland)• Roland Leucker (Germany)• Ulf Lundström (Sweden)• Toshiro Otsu (Japan)• Xavier Ponticq (France)• Norman Rhodes (UK)• Marien Riemens (Netherlands)• Juan Manuel Sanz (Spain)• Peter Sturm (Austria)• Fathi Tarada (UK)• Pauli Velhonoja (Finland)

Reviews were provided by Wah Onn Adrian Cheong (Singapore), Boon Hui Chiam (Singapore), Gary English (USA), Jorgen Holst (Denmark), Ryu Ji Hyun (South Korea), Nam-Goo Kim (South Korea), Ronald Mante (Netherlands), Frederic Walet (France), Urs Welte (Switzerland), Franz Zumsteg (Switzerland). Additional reviews provided by Bernhard Kohl on behalf of BASt and Dirk Sprakel on behalf of COSUF.

The Working Group was chaired by Leslie Fielding (UK) and Bruce Dandie (Australia) was the Secretary.

The English editors of this report were Bruce Dandie (Australia) and Norris Harvey (USA). The translation into French of the original version was undertaken by Sylvain Garnier (France) and Xavier Ponticq (France).

This report was developed over two PIARC cycles. During the 2008-2011 cycle, the working group was led by Arnold Dix (Australia).

The Technical Committee was chaired by Ignacio Del Rey (Spain) with Marc Tesson (France), Fathi Tarada (United Kingdom), Juan Marcet (Argentina) respectively being the French, English and Spanish speaking secretaries.

EXECUTIVE SUMMARYFIXED FIRE FIGHTING SYSTEMS

IN ROAD TUNNELS: CURRENT PRACTICES AND RECOMMENDATIONS

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I

Fixed Fire Fighting Systems (FFFS) have been routinely used in road tunnels in countries such as Japan and Australia for decades, and there is increased interest in the use of FFFS in parts of Europe, North America and Asia.

Large fire events in road tunnels continue to show the consequences of such an event. These consequences can be to the users, the tunnel infrastructure, and the impact to the wider road network on society. This has maintained the pressure for further improvements to techniques and technologies to manage the risk and consequence of fires in road tunnels. FFFS are increasingly seen as a method that can deliver user safety and infrastructure protection, and can be used as a risk reduction measure. However, their use is not widespread for various political, economic, technical and social reasons. It is still recognised that FFFS may not be the most appropriate measure to adopt in all circumstances or in all locations.

Within this report, the functional impact FFFS can make to the performance of tunnel fire safety systems is discussed. Information is presented about the types of systems available, their use in road tunnels for various countries, and advice provided on the design and selection of appropriate FFFS. Where FFFS are adopted, it is essential that they are correctly designed, installed, integrated, commissioned, maintained, tested and operated. Where FFFS are installed, it is recommended that they are activated in the early stages of a fire to minimise fire growth and to provide the desired effectiveness.

FIXED FIRE FIGHTING SYSTEMS IN ROAD TUNNELS… 2016R03EN

CONTENTS

1. INTRODUCTION ...........................................................................................................................................................3

1.1. PURPOSE OF THIS REPORT .........................................................................................................................3

1.2. SCOPE OF THE REPORT ...............................................................................................................................3

1.3. TARGET GROUP ..............................................................................................................................................4

1.4. THE ROLE OF FIXED FIRE FIGHTING SYSTEMS ..................................................................................4

2. PREVIOUS WORK ........................................................................................................................................................6

2.1. PIARC PUBLICATIONS .................................................................................................................................6

2.2. OTHER REPORTS AND GUIDANCE ...........................................................................................................8

3. DECISION FACTORS ...................................................................................................................................................9

3.1. INTRODUCTION .............................................................................................................................................9

3.2. COMPLIANCE WITH REGULATIONS, GUIDELINES AND LEGAL CONSIDERATIONS ...............9

3.3. RISK ASSESSMENT ........................................................................................................................................9

3.4. LIFE SAFETY .................................................................................................................................................10

3.5. ASSET PROTECTION ...................................................................................................................................12

3.6. ADDITIONAL TRAFFIC REGIMES ...........................................................................................................13

3.7. FIRE-FIGHTING RESPONSE ......................................................................................................................13

3.8. OPERATIONS, MAINTENANCE AND REGULAR TESTING ..............................................................14

3.9. COST BENEFIT CONSIDERATIONS .........................................................................................................14

3.10. SUSTAINABILITY ......................................................................................................................................16

3.11. LEGAL CONSIDERATIONS ......................................................................................................................16

4. DESIGN CONSIDERATIONS .................................................................................................................................. 17

4.1. RISK ASSESSMENT ......................................................................................................................................18

4.2. TYPE OF SYSTEM ........................................................................................................................................19

4.3. WATER DISCHARGE CHARACTERISTICS (MIST OR DELUGE) .....................................................19

4.4. WATER SUPPLY ............................................................................................................................................20

4.5. DRAINAGE .....................................................................................................................................................21

4.6. SPACE CONSIDERATIONS .........................................................................................................................21

4.7. FIRE DETECTION AND ACTIVATION STRATEGY ...............................................................................21

4.8. TUNNEL ENVIRONMENT...........................................................................................................................22

4.9. SYSTEM INTEGRATION .............................................................................................................................23

4.10. INTERACTION OF FFFS WITH VENTILATION ...................................................................................24

4.11. FURTHER ASPECTS ...................................................................................................................................28

5. SYSTEM DEFINITION / PROCUREMENT .........................................................................................................28

5.1. SYSTEM DEFINITION .................................................................................................................................28

5.2. TESTING AND COMMISSIONING ............................................................................................................33

5.3. APPROVALS ...................................................................................................................................................33

5.4. TRAINING .......................................................................................................................................................33

5.5. COST ................................................................................................................................................................33

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6. RESEARCH AND ANALYSIS ..................................................................................................................................34

6.1. RESEARCH PROGRAMS .............................................................................................................................34

6.2. MODELLING .................................................................................................................................................35

7. CONCLUSIONS AND RECOMMENDATIONS ...................................................................................................36

7.1. CONCLUSIONS .............................................................................................................................................36

7.2. RECOMMENDATIONS .................................................................................................................................36

7.3. FUTURE WORK .............................................................................................................................................37

8. BIBLIOGRAPHY / REFERENCES .........................................................................................................................38

9. GLOSSARY ...................................................................................................................................................................43

10. APPENDICES .............................................................................................................................................................44

APPENDIX 1 - QUESTIONNAIRE DATA .........................................................................................................44

APPENDIX 2 - TYPES OF SYSTEMS ...............................................................................................................58

APPENDIX 3 - MAINTENANCE AND TESTING ...........................................................................................68

APPENDIX 4 - RESEARCH AND EVALUATION PROGRAMS ...................................................................71

APPENDIX 5 - MODELLING ..............................................................................................................................75

APPENDIX 6 - SUSTAINABILITY ....................................................................................................................77

FIXED FIRE FIGHTING SYSTEMS IN ROAD TUNNELS…3

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1. INTRODUCTION

1.1. PURPOSE OF THIS REPORT

This report replaces the previous 2008 PIARC guidance on Fixed Fire Fighting Systems (FFFS) Road Tunnels: An Assessment of Fixed Fire Fighting Systems [30]. It advances the understanding of FFFS, their application, benefits and limitations, as well as providing advice on the design, procurement installation, testing, commissioning, maintenance and operation of FFFS. The report also looks at international experience based on current installations, test programmes and real life incidents.

Since the publication of the 2008 report, a greater understanding of FFFS has expanded their use and application around the world. This has occurred as a consequence of test and research programmes, incident data reports from existing FFFS, and the development of designs for new and existing tunnels.

In some countries, risk and cost benefit analyses are used to consider the application of FFFS as a measure to assist in making infrastructure both safer, and more durable in the event of an incident. However, for various political, economic, technical, and social reasons, it is recognised that FFFS may not be the most appropriate measure to adopt in all circumstances. These reasons can include where a road tunnel has a dedicated fire service to provide a similar response in a timely manner, where government directive asserts that FFFS will not be applied in that particular country’s tunnels, or where FFFS will not be maintained and operated to the degree of reliability and availability required. Where FFFS are installed, it is essential that they be correctly designed, installed, integrated, commissioned, maintained, tested, and operated with a high level of reliability and availability, so that the systems are available for use as required.

The purpose of this report is to provide decision makers and designers with information to assist them with their understanding of the parameters of FFFS, and to provide guidance on whether or not to include FFFS in their road tunnels.

1.2. SCOPE OF THE REPORT

The scope of this report is to provide strategic guidance and advice on FFFS to allow their implementation to be considered in a balanced manner. In doing this, the report provides information on the application of FFFS, including the design, procurement, installation, integration, testing, commissioning, operation and maintenance of water-based FFFS in tunnels. The report consolidates current and previous work by PIARC and other organisations, and includes data from numerous full-scale fire tests where data were available.

The term FFFS refers to a range of technologies that use water as the suppression agent, or water with an additive or some other extinguishing agent. These systems are installed as part of the tunnel infrastructure and require no additional elements to be added when called upon to fight fires. As such, these systems are part of the fixed installation, having been installed for the specific purpose of controlling a fire incident over a specific area and are activated automatically, semi-automatically, or manually from a remote location. Therefore, the term FFFS does not apply to manual fire-fighting methods that only have a portion of the infrastructure fixed, such as the case with standpipes and hydrants.

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1.3. TARGET GROUP

The Target Group for this report is road authorities, tunnel owners, tunnel operators, and tunnel managers. This report is also intended to be of benefit to designers, emergency services, contractors, tunnel safety officers, and the industry in general.

1.4. THE ROLE OF FIXED FIRE FIGHTING SYSTEMS

The role of FFFS for road tunnels is to provide facilities for tunnel owners and operators to assist with the early suppression and subsequent management of fires. In this manner, the consequences of a fire event to tunnel users, the tunnel infrastructure, and the societal impact due to disruption to the wider road network can be mitigated. Their installation provides the fixed infrastructure within a tunnel to enable fires to be addressed more quickly and more easily than if incident responders had to provide and deliver alternate systems to the fire site to respond to the event by other means.

As FFFS are part of the tunnel infrastructure, they allow fire control to be initiated from a remote location automatically, semi-automatically, or manually. This provides advantages in that FFFS allow:

• fires to be addressed in a timely manner, even before the fire brigade arrives at the incident site;• delivery of sufficient water to the fire site, such that control or suppression of a fire can occur

before the fire develops into a full scale conflagration;• the fire brigade to manage the fire incident without putting themselves at risk by being in the

near vicinity of a fire; and• the fire brigade to fully extinguish the fire once it has been suppressed (if it has not already

been extinguished).

As a fire is able to be addressed in a timely manner, the operation of FFFS should occur while the fire is still in the growth phase. This permits FFFS to be more effective than if they were applied to a fire when it had developed to a full scale conflagration. By applying water directly to the fire site, FFFS retard the growth rate of the fire by cooling the surface of the burning material and inhibiting the combustion process. The end result is that the consequence of a fire is reduced, enhancing life safety and reducing damage to the tunnel structure and tunnel equipment. FFFS also provide more tenable conditions for the fire brigade to access and fully extinguish the fire.

Properly designed, installed, integrated, commissioned, maintained, tested and operated FFFS will:

• provide early suppression and control of a fire event;• retard the fire growth rate, thereby inhibiting the combustion process and reducing the heat

output;• remove heat from the environs of the fire by cooling the surrounding area during an incident;• limit the potential for fire to spread between vehicles;• extend the available escape time for tunnel users;


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• improve overall tenability for fire fighters, enabling them to respond to the event more effectively;

• reduce the likelihood and extent of structural damage;• limit the severity and extent of damage to tunnel systems and equipment;• allow the asset to return to service in a shorter period of time following a fire; and• return the external road network to full integrity in a shorter period of time following a fire.

Water based FFFS in tunnels can be divided into Deluge Systems and Water Mist Systems, both with and without the use of foam additives. However, water based systems without additives represent the vast majority of installed systems. Even though Deluge Systems and Water Mist Systems use valves to enable operation over a discrete zone of the tunnel, the terms Deluge Systems and Water Mist Systems having the predominant features as described in chapters 1.4.1 and 1.4.2, will apply herein.

Where FFFS are installed, it is essential that they be correctly designed, installed, and integrated into the tunnel system, as well as properly tested, commissioned, maintained, and operated. Where installed, it is recommended that activation should occur in the early stages of a fire to minimise fire growth and ensure the desired effectiveness.

1.4.1. Deluge Systems

Deluge Systems are typified by a zoned water application, characterised by a significant proportion by volume of relatively large water droplets. With Deluge Systems, the size of the water droplet counters the extent of drift that may occur with longitudinal ventilation systems. The exact performance of these systems varies from tunnel to tunnel as their performance is usually specified as an application rate over a discrete section of tunnel, or as a delivered density application rate in mm/min or l/min/m2, and not on the basis of droplet size distribution (appendix A2.2, page 58 for a more detailed description). Deluge Systems predominantly control a fire by removing heat and inhibiting the combustion process by cooling surfaces directly at and adjacent to the fire site.

1.4.2. Water Mist Systems

Water Mist Systems can be either low or high pressure, however, the pressures used are typically higher than those used for Deluge Systems. Water Mist Systems are typically used where the volume of water, spatial considerations, or weight restrictions, are an issue. Water Mist Systems are characterised by relatively fine water droplets, which assist cooling by the evaporative process. Some droplets get entrained to the seat of the fire by air convection, while others reach the fire from above due to the high momentum imparted to them. Also, due to the high momentum, drift along the tunnel due to longitudinal ventilation systems or external ambient pressure effects is generally minor. Mist systems are specified based on the volume of the tunnel in the application zone in l/min/m3 (appendix A2.3, page 63 for a more detailed description). Water Mist Systems predominantly operate by gas cooling and provide limited cooling of surfaces immediately at and adjacent to the fire site.

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1.4.3. Common Features and Variances

Both systems are characterised by:

• a water supply with sufficient reliability, quality, quantity and pressure for application at the required rate over the designed tunnel area;

• an activation valve (typically a deluge valve, section valve, or a solenoid) that controls the flow of water to the distribution network and hence does not rely on localised fusible link sprinkler heads;

• a water distribution network between the activation valve and the spray nozzle;• the ability to deliver a predefined volume of water over the designated fire zone for a

predetermined period of time.

Water Mist Systems vary from Deluge Systems in that Water Mist Systems typically:

• use higher pressures than Deluge Systems;• use smaller diameter pipework than Deluge Systems;• uses less water volumes and flow rates for the same area of coverage;• use more specialised material and equipment such as for pumps, pipes and nozzles due to

the higher operating pressure, and the requirement to keep the fine spray nozzles clear of any particles that may occur in the pipe network and block the nozzle openings. The need to eliminate blockages may also require the addition of filtration systems.

2. PREVIOUS WORK

The use and application of FFFS in tunnels has been debated for many years both within PIARC and other eminent organisations. In recent years, the situation has changed from a position where FFFS were not recommended, to that where FFFS are noted as having benefits both during a fire event and in returning the asset to service following a fire event. This change in position is reflected in the increasing volume of documentation and guidance that has arisen as technical knowledge of FFFS has improved by actual applications; a significant number of large scale fire tests and test programmes; and incident data reports on the effectiveness of properly designed, installed, integrated, commissioned, maintained, tested and operated FFFS.

2.1. PIARC PUBLICATIONS

Publications of the World Road Association (PIARC) on FFFS over the years are summarised below.

2.1.1. 1999 - Fire and Smoke Control in Road Tunnels

In 1999 the PIARC publication Fire and Smoke Control in Road Tunnels [29] chapter VI.3.3 Water Supply, and chapter VI.3.4 Sprinklers, reviewed previous work by PIARC and made recommendations for the provision of a fixed water supply and the use of sprinklers. It recommended that water supply standpipes be provided for tunnels greater than 200 m and that hydrants for fire brigade use be placed at a spacing of 100 to 200 m (refer chapter VI.3.3.3). However, it also noted that sprinklers were not commonly used because “… most fires start in the motor room or in the compartment, and sprinklers are of no use till the fire is open. Sprinklers


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can be used, however, to cool down vehicles, to stop the fire from spreading to other vehicles (i.e. to diminish the fire area and property damage) and to stop secondary fires in lining materials. Experiences from Japan show that sprinklers are effective in cooling down the area round the fire, so that fire fighting can be more effective” (refer chapter VI.3.4.3). It stated that the use of sprinklers could be problematic because:

• water can cause explosion in petrol and other chemical substances if not combined with appropriate additives;

• there is a risk that the fire is extinguished but flammable gases are still produced and may cause an explosion;

• vaporised steam can hurt people;• the efficiency is low for fires inside vehicles;• the smoke layer is cooled down and de-stratified, so that it may cover the whole tunnel;• maintenance can be costly;• sprinklers are difficult to handle manually; and• visibility is reduced.

It stated that due to the above issues, sprinklers must not be used in the region of a fire before all people have been evacuated. It concluded that sprinklers cannot be considered as equipment useful to save lives and could only be used to protect the tunnel once evacuation was completed. As a consequence, it stated that sprinklers were generally not considered as cost effective and that they were not recommended in usual road tunnels.

2.1.2. 2007 – Systems and Equipment for Fire and Smoke Control in Road Tunnels

The relevant section in the 2007 PIARC publication Systems and Equipment for Fire and Smoke Control in Road Tunnels [31] is chapter 6.4, Automatic Fire Suppression. It repeated the issues raised in the 1999 publication and restated that if sprinklers are installed in a tunnel, they must not be activated until all the people have evacuated. It did, however, note that experience in Australia, the Netherlands, and Japan showed that sprinklers may be effective in cooling down the area around the fire, so that fire fighting can be more effective and the risk of the fire spreading to other vehicles can be reduced. It acknowledged Water Mist Systems as an emerging technology and a variant to Deluge Systems, and recognised that new research work and technical development were in progress at various locations around the world.

This section concluded that, at the time of documentation, an owner/operator who wants to install new detection and new fire fighting measures must verify that they contribute to the overall safety, and are compatible with the safety concept for that specific tunnel, as well as ensuring the effectiveness of the proposed measures.

2.1.3. 2008 – Road Tunnels: An Assessment of Fixed Fire Fighting Systems

The PIARC 2008 publication Road Tunnels: An Assessment of Fixed Fire Fighting Systems [30] was intended to provide up to date information on the use of FFFS in road tunnels as current at the time of documentation. It noted that significant research work had been conducted on FFFS which provided a better insight into the advantages and disadvantages of these systems, and that the goals of these systems were to slow down fire development, and to reduce or completely prevent a fire from spreading from one vehicle to another, with the aim of improving conditions

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for escape and rescue. It also recognised that as an outcome of the loss of life and extensive damage to infrastructure from the then recent tunnel fires (i.e. Mont Blanc Tunnel - France/Italy, 24 March 1999; the Tauern Tunnel - Austria, 29 May 1999; the St. Gotthard Tunnel - Switzerland, 24 October 2001; and the Fréjus Tunnel - France/Italy, 4 June 2005) that the need for further improvements to tunnel fire management had been renewed. Post incident analysis of these fires revealed common themes and that there were numerous opportunities for improving tunnel safety following a fire incident. As a consequence, it was stated that FFFS may in some circumstances be warranted provided a systematic approach, similar to that used for all tunnel safety system components, was undertaken. Further, it was noted that before FFFS were installed in a tunnel, a systems engineering approach to their integration into the tunnel safety concept must be concluded. The interdependence between FFFS and other safety components must be understood to ensure proper performance of the integrated tunnel safety system.

The report concluded that FFFS are one of many system types available to improve user safety and infrastructure protection, and that the appropriateness of FFFS versus other system types should always be considered. Installation of FFFS should only proceed where there is an effective method, or methods, for detecting and precisely locating the fire. Without such capability, FFFS will not work effectively. The review of determining if FFFS are appropriate should include verification and validation of actual effectiveness, reliability, and performance, to ensure that appropriate and informed decisions are made. The report recommended that the cost component include installation and maintenance costs when undertaking a cost analysis.

2.2. OTHER REPORTS AND GUIDANCE

2.2.1. NFPA 502 - Standard for Road Tunnels, Bridges, and Other Limited Access Highways, 2014 Edition

Appendix E of NFPA 502 [20] Water-Based Fixed Fire-Fighting Systems in Road Tunnels discusses FFFS.

Appendix E notes that it is now widely acknowledged that FFFS are highly regarded by professional fire fighters and can be effective in controlling a tunnel fire by limiting the fire spread. This is achieved by cooling down vehicles, to stop the fire from spreading to other vehicles (i.e. to diminish the fire area and property damage), and to stop secondary fires in tunnel lining materials. It also notes that the inclusion of water-based fire fighting systems can act as a valuable component of the overall fire life safety systems in a tunnel.

It provides examples of where FFFS have been adopted in road tunnels and recommends that it “… be considered as part of a package of fire life safety measures in long or busy tunnels where an engineering analysis demonstrates that an acceptable level of safety can be achieved”. Where FFFS are applied, NFPA 502 recommends that they be activated within three minutes to prevent development of a major fire. It also notes that FFFS should be part of an integrated approach to the management of safety.

2.2.2. Other Relevant Reports

Other significant reports influencing the subject of FFFS in road tunnels include the UPTUN Report D251 Engineering Guidance for Water Based Fire Fighting Systems for the Protection of


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Tunnels and Sub Surface Facilities [26], SOLIT2 (Safety of Life in Tunnels) Engineering Guidance for a Comprehensive Evaluation of Tunnels with Fixed Fire Fighting Systems [24], and the BASt reports BASt 2014a [35] and BASt 2014b [36].

3. DECISION FACTORS

3.1. INTRODUCTION

When deciding whether or not to install any type of FFFS, the following must be examined:

• compliance with local regulations and guidelines, including legal considerations;• global guidelines and safety standards;• the functions and roles of FFFS in the safety concept;• life safety;• asset protection and the protection required to assure the availability of the transport link;• flexibility for additional traffic regimes such as Dangerous Goods Vehicles (DGVs);• fire-fighting response;• the ability to adequately operate and maintain the system, including the roles, positions, and

responsibilities of the stakeholders;• the installation capital cost and/or life cycle cost, as well as the cost benefit from installing FFFS; • system reliability and redundancy; and• sustainability, as this may also be a factor in the decision.

Design considerations are addressed in chapter 4, page 17.

3.2. COMPLIANCE WITH REGULATIONS, GUIDELINES AND LEGAL CONSIDERATIONS

The tunnel regulations of most countries do not prescribe installing FFFS. In fact, the attitude of various countries around the world to FFFS varies. Some countries choose to make it mandatory to install FFFS in all road tunnels. Notably, this is the case in Australia (refer Appendix 1, page 44 for examples) and for longer tunnels in Japan (over 3 km). Equally, some countries choose not to consider FFFS, and in some countries, the option of installing FFFS is considered on a case by case basis by regulators and project stakeholders. This possibility may be expressed in the relevant national standard or guidance, or may be treated by exception for each case.

Where FFFS are not mandatory and are permitted, the risk profile associated with the road tunnels should be considered. Key factors include the location and characteristics of the tunnels, the nature of the vehicle fleet, traffic volumes, and goods transported. Funding priorities also vary from country to country and have to reflect the safety concerns, public attitudes to safety, and policies specific to each country. It is relevant to note that the European Directive on minimum safety requirements for road tunnels [38], which applies to 28 countries with widely varying tunnel risk profiles, does not mention FFFS.

3.3. RISK ASSESSMENT

Each country uses differing means to determine how safe a tunnel is and whether that level of safety meets its unique requirements and circumstances. This means that the level of safety

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required, and the levels of safety achieved, vary from country to country and as knowledge and circumstances change.

The installation and operation of FFFS does not make a tunnel safe, nor does not using FFFS make a tunnel unsafe. A useful way to evaluate the level of safety achieved in a tunnel is to conduct a risk assessment.

In most countries installation of FFFS is not prescribed by tunnel regulations. Therefore, they typically are an additional safety measure which may be applied to mitigate specific risks or to compensate shortcomings in tunnel design and other equipment. In the context of an integrated tunnel safety design risk assessment, tools may be applied as support for decision making, to demonstrate how and to what extent FFFS are suited to compensate specific risks, taking the interaction with other tunnel safety facilities and safety relevant operational rules into account. For this purpose, it is preferable that quantitative system based methods should be applied containing simulation tools capable of modelling tunnel fires, smoke propagation and the effects of FFFS on fire development, heat and smoke. This is discussed in the PIARC publication Risk Evaluation, Current Practice for Risk Evaluation for Road Tunnels [37]. Such an approach can also be applied to identify opportunities to attenuate other safety measures with overlapping effects and demonstrate the improved efficiency. For example, some reduction in the overall capacity of the ventilation system and the structural fire protection may be justified without reduction of the overall fire life safety goals.

As noted in the publication on Risk evaluation for road tunnels [37], risk analysis is a tool for assisting with decision making and has limitations related to simplification of data, assumptions and risk weightings.

3.4. LIFE SAFETY

Life safety should be viewed from the perspective of the following groups:

• tunnel users;• tunnel operations and maintenance staff;• emergency Services personnel; and• people external to the tunnel (e.g. people in buildings above the tunnel, or near the portal).

FFFS may improve conditions during a fire event by reducing the fire growth, the gas temperatures and radiant heat fluxes. By reducing the fire growth and ultimately the fire size in megawatts, the production of toxic gases, as well as smoke, may be reduced. This is particularly relevant for self-rescue by tunnel users, however, to benefit self-rescue, early activation of FFFS is essential to assure that the fire size remains as small as possible.

Tunnels should have an acceptable level of safety for all tunnel occupants. During a fire incident, survivability in the fire zone is dependent on occupants escaping to a place of safety or reducing and controlling the fire to an extent that it does not pose a hazard. In the area close to a fire, there may be untenable conditions due to the effects of the fire (definitions of tenability are available in the PIARC publication Fire and Smoke Control in Road Tunnels [29] chapter 1.5; and in NFPA 502 2014 [20] appendix B). Untenable conditions for human life comprise heat (including radiant heat) and oxygen content (or its replacement by CO2) and toxic gasses produced by


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combustion, such as HCN and CO. Note that visibility is sometimes included as a tenability criterion as it can affect wayfinding, however, if anyone is injured and unable to self evacuate from the fire zone, this criterion is of less relevance than other criteria.

Untenable conditions close to a fire zone can occur regardless of whether FFFS are used or not. The effects of FFFS on the production of toxic chemicals such as CO or more smoke production are not clearly understood. Negative influences on these variables are counteracted by early activation of FFFS. Furthermore, until a fire is totally extinguished, it may not be possible to determine if the fire will flare up, or if some form of structural collapse may occur. In either case, if there are any injured occupants in the fire zone, it is imperative to get them to a place of safety so that proper treatment and triage can be accomplished. Anyone responding to a fire event in a tunnel must first ensure their own safety before attempting rescue. The advantage of FFFS is that they retard the fire growth rate and therefore the survivability of any injured occupants is enhanced, as is the potential for responders to rescue anyone that is injured and cannot self evacuate.

Tests and computational analysis demonstrate that the vertical impulse of activated FFFS may transfer the higher concentrations of toxic gases in the upper levels of the tunnel cross section towards lower parts; this effect has been observed in measurements of full scale tests [70]. Although no adverse effect of this phenomenon has been observed in real events involving activation of FFFS, it again highlights the importance of the activation strategy and the ventilation system for protection of life safety.

Visibility is also important for self-rescue. The application of FFFS will have an impact on visibility through the presence of water where visibility is reduced. Another aspect is the impact of FFFS on smoke. Smoke stratification, especially in the activated suppression zone, will be degraded if not destroyed by employing FFFS. This may impede wayfinding and increase smoke concentrations in the downstream zone. However, this has to be viewed from the consideration that FFFS should be activated as soon as possible and that consequently, the temperatures, heat release rates (HRRs), and volume of smoke produced are reduced, which all have a positive impact on the tenability conditions in the tunnel.

On the other hand, there is at least a theoretical risk that activating FFFS could discourage people evacuating from their vehicles due to their apprehension about the water discharge, especially in situations when the potential threat of a developing fire is not yet perceived. In documented events this risk has not been observed - but it does appear credible.

People must be persuaded to leave their cars for their own safety. Measures to improve this response can be sound beacons, public address (PA) systems, guidance lighting, contour lighting around the doors, strobe lights, and radio re-broadcast (RRB) and other similar systems [68]. The 2007 Burnley Tunnel fire (Melbourne, Australia) demonstrated that people can be persuaded to leave their vehicles by use of appropriate cues [40].

If FFFS are used, it may be possible to optimise other fire life safety measures after detailed analysis without compromising the safety requirements. FFFS are active systems that must be maintained and operated to a high standard to work as intended. Preferably, the effects should be addressed in a quantitative manner on the basis of a risk based approach. For example, in the Northern Link Tunnel (Sweden), it was decided to maintain longitudinal ventilation and to install

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FFFS to permit traffic congestion, and hence not to install a smoke extraction system. Another example is the Felbertauern Tunnel (Austria), in which FFFS were installed as an alternative to passive fire protection to protect the fresh-air duct that serves as an egress route. In addition, FFFS may be implemented to reduce the heat-release rate of the design fire, which would reduce the required capacity of the tunnel ventilation system. The application or availability of full-scale fire test data in these instances may be relevant to have a reliable basis for such an approach.

If FFFS are used as a compensatory measure, their reliability, availability and maintainability (RAMs) need to be accounted for when assessing their benefit.

Further examples of where fire life safety was mentioned to be a factor in installing FFFS are provided in Appendix 1.

3.5. ASSET PROTECTION

With regards asset protection, the objective is to minimise the impact of the fire to the tunnel structure and/or safety and services equipment. Protection of the tunnel structure aims at reducing the damage from a tunnel fire event. In the worst case events, this could be preventing a tunnel collapse with more disastrous effects as a consequence. This can be crucial for underwater tunnels, or where large buildings or critical infrastructure are located over the tunnel. This was one of the reasons for installing FFFS at critical locations on the M30 Tunnels in Madrid (Spain).

Asset protection can also be considered in terms of reducing the down-time of a tunnel subsequent to a fire. This may be particularly important where a tunnel is a critical part of the road network or a toll road. These benefits were demonstrated by the Heavy Goods Vehicle (HGV) fire in the Burnley Tunnel Toll Road fire (Melbourne, Australia) in 2007. The severe incident involving multiple HGVs and cars, with immediate deflagration, was limited to less than 20 MW by rapid activation of the installed deluge type FFFS. Subsequent modelling suggested that without FFFS activation the fire would have rapidly grown to more than 100 MW [40]. The FFFS limited damage to the structure and services, and allowed the tunnel to be reopened within a few days. Similarly, this was one of the reasons for the installation of FFFS on some of the privately owned tunnels on the A86 ring road in Paris (France).

FFFS may be considered as a compensatory measure in fire-engineering design. It is recognised that passive measures are normally considered to be the most reliable, nevertheless, in some circumstances, it may be possible to reduce the level of passive fire protection. This can be useful, for example for refurbishment projects, where there are physical constraints such as a lack of space, or operational constraints on when a tunnel can be closed for refurbishment works. In some tunnels, FFFS have been used in the smoke-extraction duct to cool the exhaust air so that the smoke extraction fans are not exposed to the high temperatures that otherwise might render the fans inoperable.

Where FFFS are critical for asset protection, careful consideration must be given to their reliability, and appropriate redundancy may be required to achieve the availability criteria desired. Certainly, the consequences of failure of FFFS to operate on demand must be considered. Passive fire protection may offer some advantages in this respect, but would not protect equipment located within the tunnel space.


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Some examples of where protection of the asset and transport link was mentioned to be a factor in installing FFFS are given in appendix 1, page 44.

3.6. ADDITIONAL TRAFFIC REGIMES

The impact of HGV fires can be reduced using FFFS and therefore can lead to a tunnel allowing the passage of dangerous goods transport where otherwise this would not be permitted. However, some aspects of HGV fires, while improved, may not be eliminated, such as the release of toxic gases. The effectiveness of FFFS may not prevent extreme events such as a Boiling Liquid Expanding Vapour Explosion (BLEVE), but can reduce the probability of its occurrence [12]. This was the main reason for installing FFFS in the Gnistängs Tunnel in Gothenburg (Sweden) in which FFFS will also be engaged on fires with dangerous goods vehicles.

FFFS can reduce fire growth and fire spread between vehicles, which is particularly important in a congested traffic situation. Further examples of where this was mentioned to be a factor in installing FFFS are given in appendix , page 44. These examples include the Felbertauern Tunnel in Austria and the Roermund Tunnel in the Netherlands.

3.7. FIRE-FIGHTING RESPONSE

A fire hose has a limited ability to project a water jet onto a fire in a tunnel environment due to the constraint the tunnel roof poses in limiting the height of the water jet. As a consequence, fire fighters need to be closer to a fire in a tunnel environment than they would otherwise be in an ambient environment. This exposes fire fighters to greater risk of the effects from the fire due to their proximity.

However, even with specialised equipment which permits fire fighters to withstand higher radiant heat, there are limits to the gas temperatures, levels of incident radiated heat flux, and exposure duration that may be endured. This means that fire fighters may be unable to approach a fire to reduce its size or even significantly reduce the radiated energy levels. In a Swedish research project, it was concluded that it becomes difficult to fight fires above about 25 MW [14]. To fight large fires without putting fire fighters at risk, FFFS can be installed.

Although fire fighters may reach the tunnel quickly, commencement of fire fighting operations may take a significant period of time in some tunnels. This time can be between 5 to 25 minutes after arrival depending on the nature of the incident. Consequently, if the fire is allowed to grow freely, it may quickly become too severe for fire fighter intervention.

FFFS will, in most circumstances, retard fire growth. The final extinction of the fire requires intervention by the fire brigade. Procedures for fire fighter response should include the provision that FFFS should not be turned off until it has been ensured that the fire is under effective control.

In some cases, such as where the local fire brigade are located very close to the tunnel, the additional benefits provided by the installation of FFFS may be reduced.

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3.8. OPERATIONS, MAINTENANCE AND REGULAR TESTING

Maintenance of FFFS includes all technical, operational and administrative requirements to ensure the system performs as specified during its design life. Regular maintenance of FFFS commences immediately after the initial testing, commissioning and proving of the system.

Installation of FFFS can only be considered if the Tunnel Owner can commit to the provision of supporting operation and maintenance regimes. To provide effective protection in the event of a fire, FFFS must be adequately maintained, regularly tested throughout the life of the system, and operated by suitably trained personnel. If this cannot be assured, then the benefits of FFFS will be considerably diminished in a fire event, if not negated altogether. A strict routine of staff training, system testing and maintenance of the system must be employed, or these activities can be outsourced to a specialist company. Some testing of FFFS may also require some form of tunnel closure (appendix 3, page 68).

The decision when to activate the system is part of the overall operational strategy. Early activation offers the greatest chance for fire control and can be important to ensure that FFFS are not disrupted by the fire prior to their activation. Consideration should be given to methods for confirming the fire location, and stopping traffic before system activation. To achieve this, clear plans and procedures are necessary for operations.

Installation of FFFS should not adversely affect safety during normal operations. The consequences of false activation should therefore be considered, as should system safeguards to prevent this type of event. The importance of preventing false activation is clearly demonstrated in the Central Artery North Area (CANA) Tunnel where the Deluge System was taken out of service due to several accidental activations.

Further details on testing and maintenance are given in appendix 3, page 68.

3.9. COST BENEFIT CONSIDERATIONS

The design life of a system can be defined as the period from the start of operational use until the time the system needs total replacement. It should be noted that some components of the system may need to be replaced a number of times during the design life of the total system. For FFFS, the design life is typically 20 to 30 years depending on the materials used. Details on costs in general are found in chapter 5.5, and examples from various tunnels in appendix 1, page 44.

The decision whether or not to install FFFS may be supported by an assessment of the costs and benefits. For this purpose, various approaches may be adopted. For example, decisions may be based on the subjective opinions of key stakeholders, or an approach may be taken where the costs and benefits are measured in some qualitative or semi-quantitative way, or a fully quantified business case may be prepared utilising cost benefit analysis techniques.

Considering the subjective approach, a key stakeholder may advocate the installation of FFFS on the basis that the system will limit fire spread, and reduce the potential fire and smoke hazards in the tunnel. In some cases, the stakeholder’s perception of the safety benefits and public opinion may be sufficient to determine the outcome.


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At the other extreme, a formal business case might be needed that compares the capital, operating and maintenance costs with the benefits of reduced injuries, damage and traffic disruption, over a specified period such as the design life of the FFFS adopted or the tunnel. The output would be an estimate of the overall cost benefit ratio.

The life safety benefits could be quantified on the basis of how many casualties would be prevented, and valuations of the benefits of preventing casualties, as published by some national authorities. These effects on risk (prevented casualties per year) could be quantified on the basis of a quantitative risk analysis. The benefits for asset protection and transport route availability could be quantified on the basis of major fires avoided, and the consequent repair and traffic disruption costs avoided. The estimated costs of repairs would include the costs of repairing the tunnel structures, renewing cables and replacing equipment, cleaning and re-painting, repairing the road surface, plus the various associated costs of undertaking site works.

The cost of traffic disruption could be estimated by the amount of time lost for the traffic participants, because of the non-availability of the tunnel that forces them to take an alternative route. This can be quantified by the Value Of Time (VOT) for the traffic participants. The VOT depends on the purpose of the journey being hindered. The VOT for recreational traffic is lower than the VOT for business traffic and HVG transports. In countries like the Netherlands, Austria and Switzerland, standardised VOT values (as well as standardised values for casualties and wounded people in traffic/tunnel accidents and calamities) are used to allow for a standardised approach for cost benefit analyses. A possible concern with a quantitative approach is whether and how to take account of subjective issues such as public opinions about tunnel safety and the availability of a transport route.

Since the fire risks and the benefits of FFFS will persist through the lifetime of the systems, it would be appropriate to consider the whole of life costs of the system, which will include both capital, operating and maintenance costs. The costs of periodic refurbishment or replacement may also need to be included, depending on the timescales adopted for decision making purposes. Certain factors would be expected to change over the period of interest such as the volume of traffic flows, equipment and labour costs, and traffic diversion costs. Trade-offs with other fire safety measures may be relevant

How each country conducts cost benefit analyses varies and reflects the large range of value systems adopted by different cultures and authorities internationally. The important element is that a cost benefit analysis be conducted.

Some authorities use standard procedures for decisions concerning highway safety, and may choose to adopt the same practices when making decisions about FFFS, on the grounds of consistency.

It is possible that the presence of FFFS as part of the tunnel’s overall risk mitigation strategy can reduce insurance rates for accidental losses and transport disruption in cases where such insurance policies exist. This is the case in Australia.

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3.10. SUSTAINABILITY

Sustainability involves broad concerns about economic, social and environmental objectives. For transport infrastructure, construction and operation increasingly include measures to improve sustainability by reducing environmental impact over the operational lifecycle. Such impacts are typically assessed in terms of carbon emissions. Most efforts to date to assess carbon emissions from facilities focus on normal operating conditions, but some consideration has been given to the influence of fires and FFFS.

To assess the impact of FFFS, it is important to understand the overall context of carbon emissions. The total carbon emission over the lifecycle of a road tunnel will include the sum of emissions from:

• construction (including materials, transportation and equipment usage);• normal operations and maintenance (notably power consumption);• periodic refurbishments (equipment and transportation for disposal of redundant materials, and

further new materials, transportation and equipment usage); and• tunnel fires (and other incidents), mitigation responses and subsequent repairs.

The direct benefit of tunnel FFFS reducing the fire risks and corresponding carbon emissions is partly negated by the carbon emissions associated with FFFS themselves and hence considered to be marginal. To achieve a larger impact on sustainability, installing FFFS would have to be associated with other design optimisations such as reducing the design fire size, slimmer or smaller structures (i.e. requiring less concrete or excavation volume), or reduced equipment costs by a reduction in equipment size or capacity.

To quantify the impact of FFFS, it is therefore necessary to quantify the potential impact of fire risks on the overall carbon emissions over the lifetime of the tunnel. A basic framework for such calculations is illustrated in appendix 6, page 79.

3.11. LEGAL CONSIDERATIONS

As is the case with all asset protection and life safety equipment, if injury or tunnel damage is caused by fire, legal investigations will likely consider the circumstances of the installation of FFFS (or the decision not to install), and any differences between how they were understood to perform and how they actually performed (refer [27] and [28]).

In some countries or regions, where FFFS have not been installed, a legal investigation will also likely consider whether FFFS should have been installed to prevent the loss in the first place. Similarly, where loss occurs with FFFS installed, the circumstances of the loss. However, the European Directive on minimum safety requirements for road tunnels [38] does not mention FFFS and within this framework, it could be assumed that FFFS are not compulsory to be considered. There are legal presumptions that FFFS, like all equipment, are optional, only installed because they are needed to manage fire risk, fit for the purpose, and that they will be integrated, operated and maintained correctly. Depending on the legal environment, Tunnel Owners and Operators may be advised to ensure that they articulate clearly why FFFS have been installed or not installed, and how FFFS are to be tested, maintained and operated.


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Prior to a decision about FFFS being installed, documentation should record the factual circumstances of the process by which the installation of FFFS was considered and agreed. For example, if FFFS are installed to protect a tunnel’s tolling revenue and for instance not needed for safety reasons. If there is no need for FFFS because the level of risk is assessed as not warranting FFFS, then the documentation should record that fact. If FFFS are installed to protect vulnerable structural portions of the tunnel, it should be ensured that this is recorded in the project documentation accordingly. If FFFS form an integral part of achieving the requisite level of safety in a tunnel, this fact should be recorded clearly.

Furthermore, the range of FFFS and the range of opportunities to install and operate them means that the anticipated performance of such systems varies and should be documented accordingly, along with the anticipated operational regime to achieve that performance. Documenting both the strengths and weaknesses of FFFS and their contribution to achieving asset protection and life safety ensures that it is seen as but one of a range of integrated risk mitigation strategies which neither individually nor collectively provides absolute safety.

Where FFFS are used as part of an integrated approach to manage safety and or asset protection, it is likely that their installation and use will impact other aspects of the tunnel design and operational strategy. For example, FFFS may reduce the size of the design fire, or the rate of fire growth used in the civil works component of the design package. Such impacts must be recorded and documented to ensure that during the operation of the tunnel, the interdependence of operable FFFS and factors such as structural integrity and evacuation performance is remembered.

Known weaknesses of the technology of FFFS should also be documented and put in context. For example, there are a range of credible false activation and other scenarios which could be identified.

Any legal investigations into FFFS installation, integration, false activation, intentional operation, expected performance or maintenance will be heavily influenced by documentation which pre-dates an incident. Like other safety systems in tunnels, it is important to record and evidence the engineering rationale that relates to the selection, installation, integration, maintenance, testing and use of FFFS.

4. DESIGN CONSIDERATIONS

This section is written from the perspective that the decision to install FFFS has already been made. Risk assessments are useful in informing the designer regarding design parameters as discussed in chapter 4.1, page 18 but they can also be used to provide a basis for determining if FFFS provide benefit to a tunnel system. The information contained in this section is intended to provide the decision maker an understanding of key design considerations including their influences on other tunnel systems.

Once it has been determined to install FFFS, the designer must establish a viable working design, and consider the following design issues in the process of developing the design of the FFFS:

• design fire; • risk assessment; • type of system;

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• water suppression characteristics (mist or deluge);• water supply including possible hydrant and/or standpipe systems;• drainage;• space considerations;• fire detection/activation strategy;• environment;• system integration;• interaction of FFFS with ventilation; and• other factors.

The objectives of FFFS may fall within a range; for example from extinguishment at one end of the scale to modest cooling at the other end of the scale, depending on the specific case. These requirements may be categorised (similarly to the categorisation in NFPA 502 [20]) as:

• fire suppression;• fire control; and• thermal exposure reduction. The term suppression may be broadly defined as a sustained reduction in the HRR following activation, control may be defined as a reduction of the HRR such that the peak is less than would be expected without FFFS, and thermal exposure reduction is the cooling of gas and shielding of radiation to reduce the exposure of people, structure and/or equipment without affecting the HRR. NFPA 502 [20] uses similar definitions, with thermal exposure reduction split further to volume cooling and surface cooling.

The design fire criteria will be derived to support the qualitative objectives, and will depend on the tunnel and traffic characteristics. Criteria should include aspects such as:

• design fire HRR and fire growth characteristics;• fire location;• ventilation conditions;• time from ignition to the commencement of suppression at the fire site;• the fire HRR at the commencement of suppression; • FFFS operating principles; and• fire test protocol, including fire location.

The qualitative objectives and derived design criteria may then be developed and defined quantitatively in the development of the design to, for example, establish the required water application rates, detection performance and activation strategy.

4.1. RISK ASSESSMENT

The designer should consider the findings from chapter 3, Decision Factors, page 9 with regards Risk Assessment and consider implications to the design approach. If necessary, additional risk analysis may be required.


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4.2. TYPE OF SYSTEM

There are two main types of water based FFFS installed in road tunnels today. These are Deluge Systems and Water Mist Systems. The main mechanisms of fire suppression for these two types of systems are different (chapters 1.4.1 and 1.4.2, page 4). Where the fuel is in liquid form, FFFS may increase the surface area of the fire.

The type of system drives fundamental design values such as water application rate, which in turn defines the required water supply in addition to the capacity of the drainage system. Deluge Systems require a higher total flow rate and hence may require additional water supplies and may have a more significant impact on the drainage systems. Water Mist Systems require a lower water supply rate, but the pressure requirements can be higher.

The choice of system can be affected by space, drainage and water supply issues, as well as the suppressive capability of either type of system. Where liquid spills occur, drainage systems can reduce the pool surface size which can reduce the fire size. In retrofit applications particularly, the drainage and water supply capacities can be crucial, and if limited, would tend toward the choice of Water Mist Systems. Power supply is also an important factor since higher pressure Water Mist Systems require significant pumping capacities in comparison with Deluge Systems (i.e. more energy is required to both pump the water to the nozzle and convert the water to mist by high pressures, than to pump water to an open nozzle).

Illustration 1 – Deluge electric pump and panel © Marina Coastal Expressway, Singapore

The risk assessment process may be used to establish the type of FFFS that will be installed. Further information on types of FFFS can be found in appendix 2, page 58.

4.3. WATER DISCHARGE CHARACTERISTICS (MIST OR DELUGE)

Water discharge characteristics are defined by water droplet size, pressures, piping layout, nozzle design and water application rate. There is a significant difference in these characteristics between Water Mist Systems and Deluge Systems.

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There is no single deterministic method for determining the water application rate. Typically the water application rate is a decision combining current practice, full scale testing and/or engineering analysis. The water application rate typically depends on the objectives for the FFFS. In some countries, such as Japan, the water application rate is pre-defined and varies from 2.5 mm/min to 12 mm/min. For further details see appendix 2, page 58.

Illustration 2 – Deluge discharge © Marina Coastal Expressway, Singapore

4.4. WATER SUPPLY

FFFS require a reliable water source and an effective distribution system. This generally requires suitable pressure and flow from the town mains, or some form of water storage. Where water from the town mains has sufficient flow but insufficient pressure, booster pumps will be required. Where water storage is required, either to supplement the town mains or to provide the required volume of water, sufficient capacity must be provided for the required duty. In this case, booster pumps will generally be required unless the hydrostatic head is sufficient to provide the pressure (e.g. where the water storage tanks are above the tunnel, or in an elevated location on a hill). The amount of water available may influence the type of FFFS selected. Tunnels can have FFFS as well as hydrants and/or standpipes. When this occurs, the designer needs to address the additional water flow and pressure requirements of all systems. FFFS may also require independent water supplies for higher reliability.

In addition to the required water supply, the designer needs to ensure that a sufficient volume of water is available to service all system requirements. The volume of water required may be specified (generally a minimum of one hour) or determined by analysis of the appropriate design fire HRR and response. This may require the provision of water tanks to provide sufficient volume of water.


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Illustration 3 – Deluge water storage tank © Marina Coastal Expressway, Singapore

4.5. DRAINAGE

With the application of FFFS, additional fluids will be added to the tunnel environment. These must be carried away efficiently and effectively. There are a number of issues to consider in designing an adequate drainage system. In addition to any normal design requirements, the capacity of the drainage system should be designed for the total water flow from the FFFS plus additional water sources such as hydrants that may operate simultaneously, and importantly, fluids that may be part of a flammable or combustible liquid spill. A properly designed drainage system can capture this liquid spill, reducing the pool surface size and therefore reduce the burn time and final fire HRR. Importantly, the drainage system should incorporate some measure by which fire is not propagated through the drainage system to some other location. For existing tunnels this provides a limitation to the design, but the risk of limited flooding may be acceptable.

4.6. SPACE CONSIDERATIONS

Space outside of the traffic envelope must be allocated for water mains, distribution piping, valves and nozzles. Height clearance for overhead installations must be such that overheight vehicles would not strike the pipework. Valve cabinets must be provided which can take significant space in the tunnel cross-section. In some instances, valve cabinets can be installed in cross-passages. The space requirements can drive the cross-passage size.

These issues can be more challenging in existing tunnels. This can potentially influence the type of FFFS that are selected. In high pressure Water Mist Systems, the pipework might be smaller in diameter, making the installation easier. Availability of ventilation ducts to route pipework may also be a factor in the choice of system, however, if this route is adopted, any effect on the ventilation system performance must be considered.

The allocation of space to FFFS must not interfere with the function of other systems in the tunnel and also must not create an additional hazard for vehicles in any way. For instance, the pipe network must not interfere with the function of jet fans, CCTV or incident detection, nor must the routing of pipework for FFFS around other systems adversely affect the hydraulic efficiency of the system.

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4.7. FIRE DETECTION AND ACTIVATION STRATEGY

A means of fire detection is essential to facilitate early and accurate activation of FFFS at the correct zone. Fire detection methods vary from tunnel to tunnel and can be automatic, operating remotely and providing an alarm without human intervention, or manual, where human intervention is required to initiate an alarm. Types of automatic detection systems include linear heat detection, spot heat detectors, smoke detectors, and CCTV based imaging technology for detection of flame or smoke from a fire. Manual fire detection systems include fire pull boxes and operator manned CCTV. In some cases, for both automatic and manual detection systems, a combination of a number of different techniques is used to minimise false alarms. However, care should be taken if this strategy is adopted. Different detection techniques have different detection times and therefore there is a possibility that a fire may be allowed to develop while waiting for a second alarm to verify and confirm the event.

Activation of FFFS can be:

• automatic, where on receipt of an alarm from a detection system the FFFS will activate automatically without delay;

• semi-Automatic, where on receipt of an alarm from a detection system the FFFS will activate automatically, but where a time delay is given for potential manual intervention either to activate the FFFS or to cancel the alarm prior to automatic activation; or

• manual, where activation of FFFS requires human intervention for the system to function.

Therefore, regardless of the detection methodology, there are a number of decisions that are required concerning the activation sequence and the mode of FFFS activation. All the methods of activation described are used in different parts of the world.

False activation of FFFS should be avoided as this may cause a collision. However, during an incident, where FFFS are activated as soon as possible, the incident vehicle should have stopped before the FFFS are activated and therefore most other vehicles should either be stopped or travelling at reduced speeds.

A fire detection system should be reliable and at a minimum identify the location of the fire such that the correct zones of the FFFS can be activated. Where the fire zone is not correctly identified, the tunnel operator may be forced to correct the activated zone. It is therefore important that the zone can be able to be activated and deactivated remotely. CCTV can be a useful tool in this process.

Current practice uses open style FFFS and not thermally operated elements. The use of thermally operated elements in a tunnel environment could result in the activation of nozzles that are not directly over the fire due to the longitudinal air velocities activating thermally operated elements downstream of the fire event. Even if thermally operated elements are activated over the fire zone, it is possible that the designed water suppression volume is not delivered to the fire site as more nozzles may be activated than permitted in the design and consequently, insufficient water is available for the design fire HRR. With thermally operated elements, this cannot be corrected as there is no way to deactivate individual nozzles remotely.


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4.8. TUNNEL ENVIRONMENT

In areas prone to freezing temperatures special arrangements may have to be made. There are multiple methods available for preventing freezing of pipes. These include trace heating, anti-freeze additives, circulation pumps with or without water heating, and insulation. A dry system might be chosen to avoid freezing issues, however, this may impact on the time required to provide water to the fire zone. In addition, the potential and effect of high temperatures also needs considering for the pump room, water supply, the water main, and the valves.

In many countries, water effluent discharge to local natural resources or even a local municipal sewer is sensitive. These issues must be addressed in the design of the system and appropriate measures incorporated to capture waste streams so that they can be processed appropriately.

Though not addressed within this report, additives to water also have design implications, such as increasing the potential for corrosion. Microbiologically induced corrosion may be possible in some areas. Use of antifreeze, if considered, should meet acceptable standards for antifreeze concentration.Corrosion is an issue in all road tunnel environments. This effect is exacerbated near salt water bodies, and in areas where salt is used for de-icing. In some countries such as Germany, all tunnel hardware is required to be a high grade stainless steel. Each road tunnel is unique and the circumstances surrounding the tunnel should be considered with respect to material selection and other corrosion protection measures.

The application of FFFS in sub-zero temperatures needs consideration for drainage where pipes and drain covers may freeze, and for road surfaces where icing may result in additional efforts, such as de-icing, to minimize possibly dangerous road surfaces.

4.9. SYSTEM INTEGRATION

FFFS must work in harmony with the other tunnel fire life safety systems. It is essential that the interdependencies between FFFS and ventilation systems be properly understood and control systems integrated for effective use. These systems include fire detection, ventilation, CCTV, traffic management and other communication systems. FFFS should not be seen as a discrete independent risk mitigation strategy but should be seen as an integral part of the fire fighting systems’ respective safety system. A discussion of these factors is given in table 1.

TABLE 1 - FACTORS ASSOCIATED WITH SYSTEM INTEGRATIONFactors Comment

Traffic Control Traffic control systems, and operational procedures, must be integrated to be compatible with FFFS activation so that activation only occurs with stopped traffic.

Ventilation If FFFS is adopted, the ventilation concept and strategy should be reviewed, and may need modification. Additionally, the system capacity may be affected.

Power Supply Higher pressure systems may require additional power to drive the pumps

CCTV Visibility may be impaired by operation of FFFS and consideration should be given to upgrading the systems if this is deemed to be an issue.

Operation Activation of system should be prompt and in the correct zones. Manual activation would involve the operator in identifying the location, etc.

Detection Needs to support operation of system in terms of accurately identifying fire location. Water Supply Water storage requirements may be considerable and this issue could be problematic in a retrofit.

DrainageNeeds to provide sufficient drainage capacity and containment. Considerations include the removal of surface water and spillages, the capacity of the drainage line, fluid containment or outfall, and ensuring fire is not propagated through the drainage system.

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Design Fire Depending on a risk assessment and the anticipated performance of FFFS the design fire HRR may be reduced in magnitude.

Tenability Tenability (visibility, temperature, toxicity and radiation) is affected by operation of FFFS. FFFS cause conditions close the fire zone to be impacted but improve conditions further away.

Egress Connected with operational issues and influenced by tenability, user action or inaction, audible and visual communication methods and wayfinding.

For activation of FFFS, the fire detection system must be able to detect a fire within a prescribed length of tunnel, which drives the design of the fire detection system.

Since the location of the fire is integral to the response of multiple tunnel systems, ventilation activation zones, zone of FFFS, detection zones, wayfinding zones and CCTV should all be integrated for optimal performance.

4.10. INTERACTION OF FFFS WITH VENTILATION

The tenability of the tunnel environment depends on factors such as smoke movement, toxic gases, gas temperatures, radiation and visibility. It is essential to consider the tenability implications of the use of FFFS when designing or activating these systems. Research has demonstrated that FFFS will reduce the air temperature and radiation from a fire but decrease visibility by disrupting the stratified smoke layer. As a consequence, shorter visibility distances may result and systems to improve the identification of egress doors, such as sounders or strobes, may be required.

Rapid deployment of FFFS is recommended to ensure that fire growth and HRR is minimised. This results in minimal impairment to visibility and provides maximum protection to the tunnel infrastructure and can allow more flexibility in design by providing the required level of safety. This approach is adopted in countries such as Japan and Australia.

Experimental measurements have shown that the HRR can be reduced by 50% or more [75] [76], and the heat transported by convection can be reduced from, typically 70%, to a maximum of 50% [72] when FFFS are operated. This effect reduces the Critical Velocity required for the control of smoke from a suppressed tunnel fire relative to a given design fire HRR.

When operating FFFS in a tunnel, allowance must be made for the fact that operation of FFFS creates extra resistance to the airflow. However, proper application of FFFS should retard the fire growth rate and hence the maximum fire HRR should be similarly controlled or reduced. This effect may also be taken into account in designing the ventilation system, if only to note this safety factor and flexibility in the design.

4.10.1. Ventilation SystemsIn general, two types of ventilation systems are used in road tunnels:

• longitudinal ventilation system; and• transverse ventilation system.

Longitudinal VentilationA longitudinal ventilation system creates an airflow within the tunnel to push the smoke and hot gases, in one direction, away from the stopped vehicles and evacuating passengers (illustration 4).


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The goal of a longitudinal ventilation system is to create sufficient airflow to oppose the buoyancy forces of the hot smoke and thereby prevent the smoke from backlayering in the direction opposite to the ventilation system airflow. The velocity of air required to achieve this airflow within the tunnel is known as the Critical Velocity. Activation of FFFS in the presence of a high air velocity may cause the droplets from the FFFS to be displaced, with the extent of displacement a function of air velocity, droplet size, and the momentum of the water droplets. However, fire tests and research projects have shown that this is not an overly serious phenomenon due to the downward velocity of the water droplets. It is also largely mitigated by minimising the longitudinal air velocity to that which is sufficient to ensure Critical Velocity (i.e. prevent backlayering). This prevents over design of the ventilation system and is good practice in any event.

Illustration 4 - Smoke displacement with longitudinal ventilation © PIARC 2008R07 - Road Tunnels: An assessment of fixed fire fighting systems

Transverse VentilationTransverse ventilation systems aim to extract the smoke by openings usually located at the ceiling or walls so that smoke is removed from the region directly at the fire, while forcing airflow toward the fire on both sides. Illustration 5 illustrates the general principle of this type of smoke control when steady conditions have been established. Initial air movement prior to activation of the ventilation system may cause smoke to move further along the tunnel before control is established. Additionally, for unidirectional traffic, the transverse ventilation system may be operated to provide a longitudinal airflow to protect traffic stopped behind the fire event. It should be noted that FFFS will disrupt the smoke layer (if any) and will affect the smoke extraction system. On the other hand, FFFS will reduce the fire HRR and hence reduce the smoke production.

Illustration 5 - Smoke extraction with transverse ventilation © PIARC 2008R07 - Road Tunnels: An assessment of fixed fire fighting systems

4.10.2. Time Scale Influence on Interaction of FFFS with VentilationThe fire will grow for an undetermined time from ignition until detection. After detection, the FFFS and ventilation system can be activated as well as other activities required by the Emergency Management Plan. The ventilation system will take time to reach full flow capacity, however, there will be an additional time period that must be considered for the ventilation system to effectively commence smoke management. These time periods should be minimised.

Immediate activation of FFFS is desirable for control of smoke and to minimise the fire HRR, however, some jurisdictions may require a delay. Designers must account for this timeline and

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ensure the owner understands the effect of delay of activation of the FFFS (typically 60 to 90 seconds from the time the systems are activated to reach the full application rate).

During the self evacuation phase, and particularly before the first responder arrives to assist those who have not self evacuated, the most important factor is the element of time and how the critical factors noted below change or evolve as a function of time:

• the progressive growth of the fire until it attains its maximum FHRR;• tenability conditions within the tunnel; and• the movement of occupants towards the escape routes.

Understanding these spatial and temporal changes is of critical importance in analysing the interaction between FFFS and the tunnel ventilation system. A classical method for representing the interaction between the critical elements listed above is a tenability diagram (illustration 6, which shows tenability conditions relative to the fire site at 3,500 m, plotted against time [39]). Tenability diagrams, used as part of risk assessment methodologies, graphically demonstrate:

• fire growth, including changing contaminant levels and temperatures;• tenability conditions, represented by visibility, temperature, CO levels;• the evacuation process; and• the ventilation strategy, represented by the movement of air.

The greatest difficulties associated with this approach are selecting the input parameters to be adopted in the models or in the test, and avoiding an unwieldy or impractical matrix of scenarios. If these difficulties can be overcome, then this type of tool has the potential to provide a better understanding of the interaction between FFFS and a tunnel ventilation system.

Illustration 6 - Example of a tenability diagram


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4.10.3. Interaction with Ventilation

It is difficult to give general criteria or recommendations regarding the interaction of FFFS with a ventilation system. Specific risks must be evaluated on a project-specific basis using risk analysis, a scenario-based approach or other techniques adapted to the particular characteristics of the tunnel and including the ventilation system and alternatives to FFFS selected.

The most common objectives of FFFS during the evacuation phase are to limit the extent of the fire, its rate of growth, and to maintain tenability for people who are evacuating, as well as emergency service personnel who are entering the fire zone. In addition to controlling the spread of the fire until emergency services arrive and commence fighting the fire, FFFS offer benefits such as increasing the fire resistance of the infrastructure, limiting the extent of fire damage and fire spread, and reducing the time necessary for repairs. However, inappropriate or poorly timed activation of FFFS can result in undesirable consequences.

Appropriate design should be undertaken to ensure that the correct zone is activated for the fire, and an engineering analysis should be performed to determine where FFFS should be installed and when they should be activated to avoid undesirable consequences.

Some general observations can be made for a few key scenarios.

Unidirectional Tunnel with Longitudinal Ventilation and No Traffic Downstream of the Fire Site• Without FFFS activation:

– downstream conditions: Expected to become untenable. – upstream conditions: Expected to be safe unless the design fire HRR is exceeded.

• With FFFS activation: – downstream conditions: May become untenable. The smoke is cooled due to activation of FFFS and the smoke layer drops. Additionally, the air temperatures decrease relative to the case without activation of the FFFS. FFFS also prevent fire spread from the point of origin. – upstream conditions: Safer than without FFFS. FFFS can assist the ventilation system by reducing the final maximum fire HRR and by reducing heat radiation. FFFS also prevent fire spread from the point of origin.

Bi-directional Tunnel, or a Unidirectional Tunnel with Longitudinal Ventilation and Traffic Upstream and Downstream of the Fire Site • Without FFFS activation: Safe evacuation conditions may be unachievable except for a short

duration during the initial fire growth phase.• With FFFS activation: The FFFS can increase the level of safety by reducing the fire growth

rate, but can also have an adverse effect by destratifying the smoke layer. The outcome depends on the location of people relative to the fire, distance to egress, the fire HRR, and smoke development. FFFS also prevent fire spread from the point of origin.

Unidirectional or Bi-directional Tunnel with Transverse Smoke Extraction• Without FFFS activation: Safe evacuation conditions may be achievable for a short period

of time if the location of the fire is accurately identified and the ventilation strategy properly selected. However, the amount of smoke generated by a fire may exceed the design extraction

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rate of the ventilation system. In this case, the ventilation system alone may not be able to handle the smoke.

• With FFFS activation: As with the longitudinal ventilation system described above, FFFS should reduce the fire size and have similar effects. As the smoke is cooler and at a higher density, the transverse smoke extraction system needs to be specifically designed. FFFS also prevent fire spread from the point of origin.

SummaryRegardless of the ventilation system type, if FFFS are properly designed, installed, well-integrated with the other safety equipment in the tunnel, and managed in accordance with established procedures, tunnel conditions during the evacuation phase can be stabilized and conditions during the fire suppression phase can be improved by FFFS. Further information on tunnel ventilation response can be found in the PIARC publication Road Tunnels: Operational Strategies for Emergency Ventilation [32].

4.11. FURTHER ASPECTS

There are additional design considerations that need to be addressed. Since FFFS can be a fire-life safety system, usually some redundancy of the system is provided. This can mean backup pumps and redundant water supply, reliable control systems and additional power requirements. Some form of reliability assessment should be undertaken as part of the design. This may, for example, be a RAMs analysis. The functional requirements of the FFFS may affect the RAMs analysis. For example the reliability requirements for FFFS used for life safety may be greater than where the system is used for asset protection.

Even though FFFS are to be expected to be activated as soon as possible, it is still expected that FFFS will continue to operate until the fire is suppressed or extinguished. Therefore, FFFS may be expected to function in a very hot environment and material selection should be carefully considered so that an elevated temperature environment can be endured while operations are not hindered. Usually water flow through the pipes will help to mitigate high temperatures, but in the event that the wrong zone is activated, the piping can be exposed to high temperatures. Where the pipe can be exposed to high temperatures, materials such as PVC piping, rubber seals for pipe connections, and other components may fail under high heat.

A maintainable system is essential to the operational resilience of the system. The FFFS should be designed such that they are readily maintainable. Further information can be found in Appendix 3, Maintenance and Testing, page 68.

5. SYSTEM DEFINITION / PROCUREMENT

This chapter considers the performance and contractual issues involved in specifying and procuring effective FFFS for installation in a road tunnel.

Uncertainties in conditions of contract can potentially lead to conflicting interpretations of the project requirements and processes by the organisations involved. This can impact the design of a system and its installation and testing. Ambiguity over the system definition and acceptance criteria can lead to project delays, increased contractual claims, and disputes. From a safety perspective, such ambiguities can result in the fundamental safety objectives not actually being achieved.


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This chapter highlights key points that should be considered by the stakeholders and by clients in particular, in order to overcome these problems.

5.1. SYSTEM DEFINITION

A first point to consider is whether particular FFFS should be specified or the choice left open to bidders. A benefit of specifying a particular type of system is that the bids from different contractors can be compared more readily. Alternatively, the question of which type of system can be left open for bidders to propose alternative solutions, in which case the requirements will need to be expressed in high level terms with performance specifications. This decision may be influenced by the system complexity and the available maintenance providers. For whichever type of system, the design should ensure compatibility of individual components before modifications or upgrades are made, and regardless of the type of system, obtaining warranties should be considered.

For procurement purposes, the system needs to be defined clearly in specifications. Useful guidance to support the preparation of a specification includes the documents published in 2006 and 2007 by the European UPTUN research project [67] [26], and the SOLIT2 guidance [23] published in 2012. These describe the general arrangements of FFFS, the interactions with other systems, system design and maintenance concerns. Of course, such guidance will not necessarily take into account the particular circumstances of a specific tunnel. Some key points to be considered when preparing the specification are outlined in the following sub-sections.

5.1.1. Fully Engineered System The installation of FFFS may be engineered in accordance with a standard such as NFPA 13 [19] or NFPA 750 [21], in a similar way to the design of fire suppression systems for industrial facilities in general. Such standards set out detailed design requirements including the nature and adequacy of water supplies, selection of nozzles, fittings, piping, valves, and all materials and accessories. This approach offers the benefit of minimising uncertainties in system definition. However, the existing standards are not sufficient for the development of fully engineered systems for road tunnels and may need supplementing for such applications.

Such standards do not take into account tunnel specific issues, such as the dynamic loading of an installation due to traffic and ventilation, or atmosphere induced effects. These issues need to be addressed by the specification.

Another potential issue is that the water application rates recommended in such standards are derived for a range of industrial and building hazards, not for road vehicles. Shielding effects tend to be a particular concern when dealing with vehicle fires. Without appropriate testing, or existing fire testing results for similar circumstances, the actual fire fighting performance of a fully engineered system is likely to be uncertain. Testing is required to provide assurance of fire fighting effectiveness. In addition, modelling is now being used in some projects as part of the assurance process (chapter 6.2, page 35).

5.1.2. Off the Shelf Systems A FFFS contractor may offer a system that is effectively off the shelf. Such a system may have been fully engineered for another tunnel or facility, but will not have been tailored for the specific tunnel. Consideration will therefore need to be given to the amount of additional design needed

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to reflect the geometry and constraints of the specific road tunnel in question. This could be a significant issue when retrofitting a system into an existing tunnel. Potential issues include conflicts between the proposed system’s piping and equipment, and the existing tunnel equipment. For example, piping routes may be blocked by the presence of tunnel luminaires, cable trays, jet fans and tunnel message signs. Piping may have to be diverted around existing equipment, which may lead to nozzles being sited inappropriately and the hydraulic efficiency of the system adversely affected.

As for fully engineered systems, the effectiveness of an off the shelf system will be uncertain unless appropriate testing or modelling is undertaken, or fire test results are already available for similar circumstances. For an existing tunnel, such testing should reflect the actual nozzle arrangements.

A key issue for clients is that it may not be obvious at the tender stage that a system being offered is really an off the shelf system with its inherent uncertainties. Of course, there may be commercial benefits in terms of reduced capital cost.

5.1.3. Performance SpecificationAn alternative or supplementary approach to an engineered or off the shelf system is to specify the actual fire fighting performance to be achieved by the FFFS. The performance is defined in terms of selected parameters such as:

• test material;• HRR versus time;• the time between commencement of the fire and activation of the FFFS;• tenability conditions, such as temperature, radiant heat flux, visibility and concentrations of

combustion products – all typically evaluated at ‘head height’;• maximum temperatures at specified points (including equipment locations) on or within the

tunnel structures; and• mechanical, hydraulic and electrical requirements (for example as defined in SOLIT 2 [24] and

UPTUN guidance [26]).

The tenability and temperature performance criteria would be specified at particular times after activation of the system, for example the maximum fire HRR and maximum temperatures after activation of the system. Time-varying criteria may be specified if the objective is to suppress or control the design size fire within a certain time period.

In the absence of existing fire test results for similar circumstances, the performance will need to be demonstrated. SOLIT2 [24] offers guidance on test protocols for fire tests. The test protocol needs to consider the tunnel geometry, the test fire load and ignition arrangements, and the ventilation characteristics (including control protocol). The timing of system activation must be consistent with the operating procedures and reflect the means of detection and the traffic management systems, procedures and self-recue requirements. FFFS contractors may be unfamiliar with such details and should be briefed to avoid any misunderstanding. It is important that the immediate review of test results not be rushed. Adequate allowances for review and repeat testing should be included. It is important to make sure that all stakeholders understand the philosophy, the implications for performance in the real tunnel and the contractual situation.


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A further key issue is that the acceptance criteria need to be agreed in advance. Ambiguity over test results and acceptance criteria can lead to project delays, increased contractual claims, and disputes.

5.1.4. Interfaces with Other SystemsRoad tunnels typically incorporate a range of tunnel structures and mechanical, electrical and traffic management systems, which are separate from, but may have interfaces with, FFFS. These include:

• tunnel structures;• automatic fire detection system (such as a linear heat detection system);• automatic incident detection systems (such as video or radar-based systems);• traffic monitoring systems;• traffic control systems (such as variable message signs, tunnel closure barriers, signs and

signals);• tunnel ventilation system;• water supplies; and• drainage systems (including sumps and disposal systems).

The performance specifications for these associated systems could be important factors to consider when preparing the performance specifications for FFFS.

Problems are more likely to occur if the FFFS contractor lacks familiarity with the general principles and practices of road tunnel design and operations. Frequent design reviews and interface management meetings should be conducted throughout the design and checking/approval phases.

5.1.5. Spatial ConstraintsFFFS will require space for their installation, both inside and outside of the tunnel. Within the tunnel bore, space will be needed for piping and possibly also for section valves. Outside of the tunnel, space may be needed for pump house(s), vehicle access routes, valves, water tank(s) and water supply connections, plus power supplies and other associated equipment. In addition, provisions may be required for manual activation by the fire service at the portals, tunnel service building(s) or control centre.

The components of FFFS will need to be regularly inspected and tested. There are generally significant constraints on when such activities can take place, for example closures may be possible only at night to minimise disruption to traffic. The specification should therefore state any particular requirements and constraints on where components are to be installed, whether inside the traffic tubes, cross passages, services gallery or equipment rooms and when equipment may be maintained.

In existing tunnels, there may also be constraints on the positioning of components of the FFFS to avoid adverse effects on the existing installations. For example, piping and valve boxes positioned directly in front of jet fans could impact the efficiency of the ventilation system. Such conflicts are more likely if the contractor lacks familiarity with the general principles and practices of road tunnel design and operations.

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For existing tunnels, site surveys of the tunnel structures, such as tunnel walls, linings and steel beams, must be done in advance to assess their suitability for the installation of FFFS before the mechanical fixings for the FFFS are designed, to avoid subsequent problems. In some old tunnels where asbestos may be present, asbestos surveys must be performed before installation of the FFFS, with removal or encapsulation of the asbestos required if it may be disrupted by FFFS operation.

5.1.6. Winter ConditionsIn countries where severe winter conditions are experienced, the system definition will need to include provisions to ensure that system operation is not impacted. The provisions could include the specification of specific materials, insulation of components and trace heating of pipes.

5.1.7. Reliability/Safety Integrity Level High system reliability is essential. Redundancy principles will generally be specified for critical elements of the system. Duty and standby units may be specified for the main pump sets, for example. RAMs analysis may be used to substantiate the likely availability of system components, taking into account the function of FFFS (whether they are used for asset protection or life safety), as well as Time Between Failures and Time To Replace data. This should be used to identify the level of reliability required for the parts of the FFFS. It should be noted that FFFS are dormant for most of the time and only activated in an emergency or during testing. Therefore, the term Probability of Failure on Demand (PFD) is therefore more appropriate than Availability in a RAMs analysis.

The control system for FFFS and other safety critical systems should be subject to strict integrity requirements. For example, a Safety Integrity Level (SIL) could be specified in accordance with EN 61508. The SIL requirements for safety integrity are based on a probabilistic analysis of the system. To achieve a given SIL, the system must meet established targets for the maximum PFD. For example, a SIL 2 system must achieve a PFD of 0.01 or less.

5.1.8. Life Expectancy The desired life expectancy of FFFS may be stated in the specification or its supporting standards. A period of the order of 20 to 30 years may be specified as the overall life expectancy of a system before it is completely replaced, for example. However, this is simplistic because the life expectancy will vary for the different parts of the system and will depend heavily upon the maintenance regime. The valves and pumps will deteriorate sooner than the nozzles and the piping. The control system and its software will probably have a life expectancy only of the order of 10 years. Some components will require replacement during the lifetime of the system, and the availability of spare parts should therefore be considered in the specification.

In practice, the life expectancy of the piping and nozzles will be heavily dependent on the materials used both in the manufacture of the components and their installation in the tunnel. For components located within the tunnel itself, the requirements for corrosion protection will need to be stated, notably including provisions to prevent corrosive effects from electrolytic action of dissimilar metals in contact with each other. The road tunnel standards in numerous countries, and certain types of high pressure Water Mist Systems, require stainless steel pipes and components, whereas other countries such as Australia generally use carbon steel pipes. Thermoplastic coated pipes have been specified for some new tunnels in Sweden.


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5.2. TESTING AND COMMISSIONING

The requirements for Factory Acceptance Tests (FATs) and Site Acceptance Tests (SATs) for FFFS will need to be specified. The requirements for tunnel FFFS are similar to those for suppression systems in general. The requirements for the control system will potentially be more complex and will need to take into account the interfaces with other systems at the tunnel.

Overall system commissioning will commence upon completion of installation and staged testing of individual FFFS components and sub-systems. All elements will need to be commissioned under service conditions.

5.3. APPROVALS

It is important that the requirements and approval process are clearly defined and understood by all stakeholders at the outset. It would be worthwhile for the stakeholders to meet at the start of the contract and go through the processes in detail to achieve a good understanding and to prevent problems at a later stage. The contractor may be unfamiliar with the highway standards and approval processes applicable for the country and tunnel in question.

Acceptance criteria defined in relation to a performance specification will constitute contractual obligations. Care is therefore needed to make sure as far as possible that the implications are understood by the contractor. For example, if the specification states a maximum fire HRR or maximum temperatures at certain times, then even small exceedances may constitute unacceptable performance. This can have serious contractual and financial implications for the parties involved.

5.4. TRAINING

FFFS form an important component of the tunnel safety measures. Training of tunnel staff involved in operations and maintenance will be essential and will need to be addressed when specifying and procuring FFFS.

5.5. COST

5.5.1. Capital Cost The capital cost of a tunnel FFFS can vary widely between tunnels and countries depending on the circumstances (appendix 1, page 44). As outlined above, there are a range of important issues that need to be considered by the client, contractor and other stakeholders to reduce the uncertainties that affect cost.

5.5.2. Testing Costs Full scale fire tests may be required as part of the procurement process, however, the cost of full scale fire testing is high, which can create commercial pressures that affect the execution, and potentially the outcome of the contract. Where full scale testing is undertaken, it is important that adequate allowance is included in the test programme and budget for the live review of results, and for repeat testing. There is generally only a single opportunity to carry out testing. It may be virtually impossible to go back to the test tunnel facility at a later stage to repeat tests if problems are subsequently identified in the results.

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5.5.3. User Costs User costs include costs for maintenance, spare parts, routine testing, training of personnel, operating costs, and energy costs. It is important that full details of the tunnel maintenance regime and key requirements and constraints are provided at the tender stage so that the FFFS can be suitably designed to minimise maintenance, and to allow realistic budgetary provisions to be made.

Maintenance costs for FFFS are dependent on the scope of work that is included. Maintenance costs typically comprise the tunnel operator’s management costs, labour costs for regular testing of the system, and the cost of replacement parts including labour. A number of tunnel operators around the world were asked to provide details of their maintenance costs. The maintenance cost for FFFS associated with the labour costs for regular system testing, and replacement parts including labour (i.e. not including the tunnel operator’s management costs as noted above), were approximately 4,200 USD per lane kilometre of the tunnel for the year 2013. Note that the tunnels surveyed included both older and newer tunnels so that the value provided is representative for all tunnels. Hidden costs may also result from a tunnel which is closed for maintenance, or testing and training. These costs may be significant in the case of toll roads and performance contracts based on high availability of infrastructure.

Other user costs include the training and re-training of persons who might be involved in inspecting, testing, maintaining or operating FFFS. Therefore, operational costs need to include the cost of training operations personnel, and if necessary, external agencies such as the fire safety services and other emergency services. This may include the costs associated with full scale functional tests such as water, additives, energy, cleaning the tunnel and personnel costs. Additional information is available in appendix 1, page 44.

6. RESEARCH AND ANALYSIS

6.1. RESEARCH PROGRAMS

The year 1999 was a turning point for the consideration of installing FFFS in road tunnels. The Mont Blanc Tunnel fire and the Tauern Tunnel fire established the potential of tunnel fires to be larger than previously considered. In 2003, the Runehamar fire tests confirmed that heavy goods vehicles have a significant potential for large HRRs, up to 200 MW. While there were other fire tests with FFFS previously, the full scale Water Mist System fire tests performed for the M30 and A86 projects, in Madrid and Paris respectively, are considered turning points for considering application of FFFS to road tunnels in Europe and North America, although FFFS have been installed in Japanese and Australian tunnels for over 30 years.

Fire tests have been traditionally performed to aid researchers in the understanding of the physics of tunnel fires, understanding the impacts of fires, and verifying calculations, assumptions, computer models, and tunnel design. Testing and research of FFFS in road tunnels has been motivated by the need to understand the performance of these systems in the context of fire development. The primary effort has been to establish the capability of FFFS to protect tunnel occupants and to allow first responders access to the fire incident. Moreover, the potential for structural protection has been of interest.


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Fire tests are primarily performed to verify the ability of FFFS to achieve the protection goals. Further, fire tests are of vital importance to Tunnel Operators and emergency responders to coordinate their efforts and verify in practice the emergency response plans.

Some of the key issues are the effectiveness of FFFS, and include various water application rates and water droplet diameters. Previously, most FFFS testing was performed for buildings and industrial applications which typically use a smaller fire HRR in design. The issue of how well FFFS perform under a larger fire HRR has also been assessed via full scale testing.

In the past 10 to 15 years, the design of many new tunnels has considered the installation of FFFS, even though they are not required. In Appendix 1 there is a survey of tunnels that have installed FFFS. In the event FFFS are considered, designers and owners have to decide the type of FFFS to install. This survey shows the variety in systems that are available and installed in road tunnels. The different types of systems are described in detail in appendix 2, page 58.

The test programs that have been performed to verify the performance of FFFS are located in appendix 4, page 71. The broad findings of these programs are also discussed. In summary, the significant findings in aggregate of these programs are: • FFFS prevent the spread of fire from one target to another;• when there is a stratified smoke layer, FFFS locally force the smoke layer to the roadway;• FFFS reduce visibility within the zones where they are activated, even without fire; • radiation effects from a fire are reduced;• maximum gas temperatures are reduced and the region of tunnel impacted by high heat effects

is significantly minimized;• fire HRR can be reduced; • steam generation is not sufficient enough to be considered a threat.

The technical benefits of FFFS have been demonstrated via full scale testing. FFFS clearly provide an effective means of managing a fire incident remotely. While FFFS have not been shown to always extinguish a fire, the evidence shows that FFFS effectively contain a fire incident and grant the local fire brigade the time and opportunity to approach a fire incident to address it directly. In addition, the region around a fire incident that may be influenced by high temperatures is significantly reduced to the fire location.

6.2. MODELLING

Computational Fluid Dynamics (CFD) has been used to model many aspects of tunnel fire safety for more than 20 years. It can be described as a mature tool to gain better insight into smoke movement and assess tenability conditions during a fire.

Analysing a problem using CFD requires the modelling of the interaction of solid fuel, liquid phase and gaseous phase fluids, pyrolysis, combustion, radiation, turbulence and heat transfer. The area that has the most uncertainty in the CFD modelling of water/fire interaction relates to the combustion models.

Performing full scale fire tests to assess the optimum parameters for FFFS and their effectiveness in a fire event is considered the ideal method to verify FFFS performance. Several comparisons

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and/or validations of various aspects of FFFS operation have been conducted through research programs and verified using CFD. However, while CFD may be used as a supplement to physical testing, it is currently not considered to be able to obviate physical testing due to the limitations of modelling the complex processes occurring during FFFS operation. Refer appendix 5, page 75 for a more detailed discussion.

7. CONCLUSIONS AND RECOMMENDATIONS

7.1. CONCLUSIONS

Fire events in tunnels continue to show the significant consequences of these types of events in a road tunnel environment to tunnel users, the tunnel infrastructure, as well as the impact to the wider road network on society. This has produced sustained pressure for further improvements to techniques and technologies to manage the risk and consequence of fires in tunnels. FFFS are a method that can deliver user safety and infrastructure protection; however, their use is not widespread for various economic, technical, political and social reasons. This report provides guidance on the decisions required before adopting FFFS and, if FFFS are to be adopted, provides guidance on the required design and implementation considerations.

Extensive testing has demonstrated that while FFFS have the ability to reduce the fire HRR and prevent the fire load reaching its full potential, high gas temperatures may still be reached that affect the structure or other infrastructure in the immediate vicinity of the fire. This has a direct link to choosing the correct design fire HRR for the design of FFFS to limit fire growth to, and the adoption of procedures to assure early activation of systems in the event of fire.

Where installed, maintained and operated effectively, FFFS have a positive impact on egress by extending the available evacuation time. This benefit applies to vehicles upstream in a longitudinally ventilated tunnel, and to both sides of a fire in a transversely ventilated tunnel. However, whilst the conditions downstream of a fire in a longitudinally ventilated tunnel are significantly improved, untenable conditions may still exist after activation of the FFFS.

The length of tunnel roadway covered by FFFS is affected by the available water supply and the tunnel width. Operation of FFFS can reduce the visibility for drivers within the area of operation, however, most vehicles within the activated zone(s) should be stopped as a consequence of the fire event. Nevertheless, procedures should be adopted to manage traffic and operate the tunnel systems without exposing motorists to additional hazards. This also means that FFFS should be reliable and the potential for false activation eliminated.

7.2. RECOMMENDATIONS

7.2.1. Design and Management Where FFFS are installed, it is essential that they are correctly designed, installed, and integrated into the tunnel system, as well as properly tested, commissioned, maintained, and operated.

7.2.2. Speed of OperationFFFS can be activated in the very early stages of fire development before fire fighting activities commence by trained fire fighters. This allows early suppression and minimises the potential adverse effects of the fire. Where installed, it is recommended that activation should occur as


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soon as possible following the fire being detected to minimise fire growth and assure the desired effectiveness.

7.2.3. Effective ProceduresFFFS should only be activated after confirming the fire location and with the incident vehicle stopped. Clear plans and procedures are necessary for tunnel operators to activate the FFFS, or effective automatically operated systems implemented.

7.2.4. Testing and Real Life IncidentsThis report provides information on full scale fire testing and the effectiveness of FFFS on real fire incidents, however, feedback from real incidents has been limited. With the increased use of FFFS in tunnels, it is important that data of where and how FFFS are operated in the future is captured and analysed to further develop the understanding and the effectiveness of these systems.

7.3. FUTURE WORK

It is suggested that the following future work or studies could be undertaken to improve the understanding and performance of FFFS:

• human behaviour and responses in a fire environment;• alternative suppression and activation techniques;• emphasis has been on the determination of ceiling temperatures in fire tests and modelling

studies. Further test data and modelling should be undertaken to determine temperatures at different heights of the tunnel wall during a fire event;

• the development of standard test procedures and protocols specific to road tunnels;• the development of a standard methodology for capturing data on fire events and the use of

FFFS so that improvements can be integrated into the system design;• the development of protocols for the specification, commissioning, and proving FFFS; • the development of on-board suppression systems for vehicles.

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8. BIBLIOGRAPHY / REFERENCES

[1] ARVIDSON, M., Fixed Fire Suppression System Concepts for Highway Tunnels, International Conference on Tunnel Fires and Escape From Tunnels, pp 129-136, Lyon, France, 5-7 May, 1999.

[2] ARVIDSON, M., Large-Scale Water Spray and Water Mist Fire Suppression System Tests, Fourth International Symposium on Tunnel Safety and Security, Frankfurt AM Main, Germany, pp 283-296 17-19 March, 2010.

[3] BRANDT, A., WIGHUS, R., Real-Scale Tests of Compressed Air Foam System in Runehamar Test Tunnel 2005, 2006.

[4] CARVEL, R.O., BEARD, A.N., AND JOWITT, P.W., The Influence of Longitudinal Ventilation Systems on Fires in Tunnels, Tunnelling and Underground Space Technology, 16, pp 3-21, 2001.

[5] CARVEL, R.O., BEARD, A.N., JOWITT, P.W., AND DRYSDALE, D.D., Variation of Heat Release Rate with Forced Longitudinal Ventilation for Vehicle Fires in Tunnels, Fire Safety Journal, 36, 6, pp 569-596, 2001.

[6] CARVEL, R.O., BEARD, A.N., JOWITT, P.W., The Influence of Longitudinal Ventilation and Tunnel Size on HGV Fires in Tunnels, 10th International Fire Science and Engineering Conference (Interflam 2004), pp 815-820, Scotland, 5-7 July, 2004.

[7] GRITZO L, et al, The Influence of Risk Factors on Sustainable Development, FM Global, chapter 3.7, 2009.

[8] INGASON, H., LONNERMARK, A., Effects of Longitudinal Ventilation on Fire Growth and Maximum Heat Release Rate, Fourth International Symposium on Tunnel Safety and Security, Germany, pp 395-406, 17-19 March 2010.

[9] INGASON, H., Model Scale Tunnel Fire Tests – Longitudinal Ventilation, SP Swedish National Testing and Research Institute, SP Report 2005:49, Boras, Sweden, 2005

[10] JÖNSSON, J., JOHNSON, P., Suppression System - Trade-Offs and Benefits, Fourth International Symposium on Tunnel Safety and Security, pp 271-282, Frankfurt AM Main, 2010.

[11] KNAPP, D., http://dknappfiredesign.com.au/interesting_tunnels_page.html.[12] LEMAIRE, A., D., MEEUSSEN, V., Effects of Water Mist on Real Large Tunnel

Fires: Experimental Determination of BLEVE - Risk and Tenability During Growth and Suppression, Efectis Nederland Report, R0425, June 2008.

[13] LEMAIRE, T., MEEUSSEM, V., Experimental Determination of BLEVE - Risk Near Very Large Fires in a Tunnel with a Sprinkler / Water Mist System, Fourth International Symposium on Tunnel Safety and Security, Frankfurt AM Main, Germany, pp 283-296, 17-19 March, 2010

[14] LÖNNERMARK, A., On the Characteristics of Fires in Tunnels, Doctoral Thesis, Department of Fire Safety Engineering, Lund University, Lund Sweden, 2005.

[15] LÖNNERMARK, A., KRISTENSSON, P., HELLTEGEN, M., BOBERT, M., Fire Suppression and Structure Protection for Cargo Train Tunnels: Macadam and HotFoam, 3rd International Symposium on Safety and Security in Tunnels (ISTSS 2008), pp 217-228, Stockholm, Sweden, 12-14 March, 2008.

[16] LÖNNERMARK, A., INGASON, H., The Effect of Air Velocity on Heat Release Rate and Fire Development During Fires in Tunnels, 9th International Symposium on Fire Safety Science, pp 701-712, Karlsruhe, Germany, 21-26 September 2008

[17] MAWHINNEY, J. R., TRELLES, J., Computational Fluid Dynamics Modelling of Water Mist Systems on Large HGV Fires in Tunnels, presented at the Journée d’Etude Technique:


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Brouillard d’Eau – Quoi de Neuf, at Pôle Européen de Sécurité CNPP - Vernon, France, 22 November, 2007.

[18] MAWHINNEY, J., Fixed Fire Protection Systems in Tunnels: Issues and Directions, Fire Technology, 2011.

[19] NATIONAL FIRE PROTECTION ASSOCIATION, NFPA 13 Standard for the Installation of Sprinkler Systems, National Fire Protection Association, 1 Batterymarch Park, PO Box 9101, Quincy, MA 02269-9101, USA, 2010 Edition.

[20] NATIONAL FIRE PROTECTION ASSOCIATION, NFPA 502 Standard For Road Tunnels, Bridges, And Other Limited Access Highways, National Fire Protection Association, 1 Batterymarch Park, PO Box 9101, Quincy, MA 02269-9101, USA, 2014 Edition.

[21] NATIONAL FIRE PROTECTION ASSOCIATION, NFPA 750 Standard on Water Mist Fire Protection Systems, National Fire Protection Association, 1 Batterymarch Park, PO Box 9101, Quincy, MA 02269-9101, USA, 2010 Edition.

[22] OTA, O., Automatic Fire Extinction (Sprinkler) System, OTA Engineering, Tokyo, Japan, December 2002.

[23] SOLIT, Engineering Guidance for a Comprehensive Evaluation of Tunnels with Fixed Fire Fighting Systems Scientific report of the SOLIT² research project, SOLIT2 Consortium, 2012.

[24] SOLIT2, Safety of Life in Tunnels 2, Engineering Guidance for a Comprehensive Evaluation of Tunnels with Fixed Fire Fighting Systems, Scientific Final Report of The Solit2 Research Project, Prepared by the Solit² Research Consortium, 2012

[25] STROEKS, R., Sprinklers in Japanese Road Tunnels, Bouwdienst Rijkswaterstaat, Directoraat-Generaal Rijkswaterstaat, Ministry of Transport, Netherlands, Project Report BFA-10012, 2001.

[26] UPTUN Engineering Guidance for Water Based Fire Fighting Systems for the Protection of Tunnels and Subsurface Facilities, European Commission research project UPTUN, Work Package 2, Fire Development and Mitigation Measures, Report D251, September 2008.

[27] UPTUN, Workpackage 2 Fire development and mitigation measures - D251: Engineering Guidance for Water Based Fire Fighting Systems for the Protection of Tunnels and Sub Surface Facilities, 2008.

[28] UPTUN, Workpackage 2 Fire development and mitigation measures - D253: Summary of Water Based Fire Safety Systems in Road Tunnels and Sub Surface Facilities, 2008.

[29] WORLD ROAD ASSOCIATION (PIARC), PIARC Technical Committee C5 on Road Tunnels, Fire and Smoke Control in Road Tunnels, 05.05.B - 1999.

[30] WORLD ROAD ASSOCIATION (PIARC), Technical Committee C3.3 Road Tunnel Operations, Road Tunnels: an Assessment of Fixed Fire Fighting Systems, 2008R07.

[31] WORLD ROAD ASSOCIATION (PIARC), Technical Committee C3.3 Road Tunnel Operations, Systems and Equipment for Fire and Smoke Control in Road Tunnels, 05.16.B - 2007.

[32] WORLD ROAD ASSOCIATION (PIARC), Technical Committee C3.3 Road Tunnel Operations, Road Tunnels: Operational Strategies for Emergency Ventilation, 2011R02.

[33] CETU, Water Mist in Road Tunnels – State of knowledge and provisional assessment elements regarding their use, Information Document, 2010

[34] APSAD, Référentiel APSAD R1: Extinction automatique à eau de type sprinkler (in French), 2014

[35] BAST 2014a: Wirksamkeit automatischer Brandbekämpfungsanlagen in Straßentunneln, (in German), Project No. FE 15.0563/2012/ERB, Bundesministerium für Verkehr und digitale Infrastruktur (BMVI), Bundesanstalt für Straßenwesen (BASt), written by ILF Consulting Engineers in cooperation with Universität Regensburg and STUVA e.V., 2014

40


[36] BAST 2014b: Wirtschaftlichkeit automatischer Brandbekämpfungsanlagen in Straßentunneln, (in German), Project No. FE 15.0564/2012/ERB; Bundesministerium für Verkehr und digitale Infrastruktur (BMVI), Bundesanstalt für Straßenwesen (BASt), written by ILF Consulting Engineers in cooperation with Amstein + Walthert AG and STUVA e.V., 2014

[37] WORLD ROAD ASSOCIATION (PIARC), PIARC Technical Committee C4 Road Tunnel Operations, Risk Evaluation, Current Practice for Risk Evaluation for Road Tunnels, 2012R23EN.

[38] Directive 2004/54/EC of the European Parliament and of the Council of 29 April 2004 on minimum safety requirements for tunnels in the Trans-European Road Network.

[39] WANG, A.X., RHODES, N., KOTTAM, K., TRAPANI, R., CFD Simulations of Ventilation Effects on Water Mist Fixed Fire Suppression Systems on Tunnel Fires, 15th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels, pp 677-686, Barcelona, Spain, 18-20 September, 2013.

[40] DIX, A., http://www.scribd.com/doc/122942826/Dix-Report-Burnley-Tunnel-Incident-2007.[41] BECHTEL/PARSONS BRINCKERHOFF, Memorial Tunnel Fire Test Ventilation

Program, Comprehensive Test Report, Prepared For Massachusetts Highway Department/Federal Highway Administration, 1995.

[42] CESMAT, E., et al., Assessment of Fixed Fire-Fighting Systems for Road Tunnels by Experiments at Intermediate Scale, 3rd International Symposium on Tunnel Safety and Security, Stockholm, Sweden, 2008

[43] CHEONG, M., CHEONG, W., LEONG, K., LEMAIRE, A., TARADA, F., Heat Release Rates of Heavy Goods Vehicle Fires in Tunnels, 15th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels, Barcelona, Spain, 18-20 September 2013.

[44] DEL REY I., ESPINOSA I., FERNANDEZ S., GRANDE A., ALARCON E., Ventilation System Design and Large Scale Fire Tests, 4th International Conference on Tunnel Safety and Ventilation, Graz, Austria, 2008

[45] Directorate-General for Public Works and Water Management, Civil Engineering Division, Project ‘Safety Test’ Report On Fire Tests, Directorate-General for Public Works and Water Management-Civil Engineering Division, Griffioenlaan 2, P.O. Box 20000, 3502 La Utrecht, August 2002

[46] FERNANDEZ, S., DEL REY, I., GRANDE, A., ESPINOSA, I., ALARCON, E., Large Scale Fire Tests for the ‘Calle 30 Project, 5th International Symposium on Tunnel Safety and Security, 2012, New York.

[47] FERNANDEZ, S., DEL REY, I., GRANDE, A., ESPINOSA, I., ALARCON, E., Ventilation and FFFS Fire Tests for ‘Calle 30’ Road Tunnels, 15th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels, Barcelona, Spain, 18-20 September, 2013.

[48] GUIGAS, X., et al., Dynamic Fire Spreading and Water Mist Test for the A86 East Tunnel, 5th International Conference on Tunnel Fires, London, UK, 25-27 October, 2004.

[49] HAERTER, A., Fire Tests in the Ofenegg-Tunnel in 1965, International Conference on Fires in Tunnels, SP Report 1994:54, p 195-214, Borås, Sweden, 10-11 October, 1994.

[50] HEJNY, H., Task 2.3: Evaluation of Current Mitigation Technologies in Existing Tunnels, Technical Report, UPTUN, 2006.

[51] INGASON, H., Fire Testing in Road and Railway Tunnels, in Flammability Testing of Materials used in Construction, Transport and Mining, V. Apted, Editor, Woodhead Publishing pp 231-274, 2006

[52] INGASON H, Model Scale Tunnel Tests With Water Spray, Fire Safety Journal 43 (7):pp 512-528, 2008.


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[53] KAWABATA, N., KUNIKANE, Y., YAMAMOTO, N., TAKEKUNI, K., SHIMODA, A., Numerical Simulation of Smoke Descent in a Tunnel Fire Accident, 4th International Conference on Tunnel Fires, p 357-366, Basel, Switzerland, 2002.

[54] KO, YOON, A Study of the Heat Release Rate of Tunnel Fires and the Interaction between Suppression and Longitudinal Air Flows in Tunnels, Doctoral Thesis Presented to the Department Of Civil and Environmental Engineering at Carleton University, Canada, April 2011

[55] Kommision für Sicherheitsmassnahmen in Strassentunneln, chlussbericht der Versuche im Ofenegg Tunnel Von 17.5 – 31.5 1965, 1965.

[56] KUNIKANE, Y., KAWABATA, N., OKUBO, K., SHIMODA, A., Behaviour of Fire Plume in a Large Cross Sectional Tunnel, 11th International Symposium on Aerodynamics and Ventilation of Vehicle Tunnels, p 78 - 93, Luzern, Switzerland, 2003.

[57] KUNIKANE, Y., KAWABATA, N., ISHIKAWA, T., TAKEKUNI, K., SHIMODA, A., Thermal Fumes and Smoke Induced by Bus Fire Accident in Large Cross Sectional Tunnel, The 5th JSME-KSME Fluids Engineering Conference, Nagoya, Japan, 17-21 November, 2002.

[58] KUNIKANE, Y., KAWABATA, N., TAKEKUNI, K., SHIMODA, A., Heat Release Rate Induced by Gasoline Pool Fire in a Large-Cross-Section Tunnel, 4th International Conference on Tunnel Fires, 387-396, Basel, Switzerland, 2-4 December, 2002.

[59] OPSTAD, K., STENSAAS, J.P. BRANDT, A. W., Task 2.4: Development of New Innovative Technologies, Technical Report, UPTUN, 2006.

[60] SHIMODA, A., Evaluation of Evacuation Environment During Fires in Large-Scale Tunnels, 5th Joint Workshop COB/JTA p 117 - 125, Japan, 2002.

[61] SOLIT, KRATZMEIR, S., Safety of Life in Tunnels, Forschungsbericht Solit - Wassernebelanlagen in Strassentunneln (Only available in German), 2007

[62] TUOMISAARI, Maarit, Full-Scale Fire Testing For Road Tunnel Applications – Evaluation Of Acceptable Fire Protection Performance, Proceedings from the Third International Symposium on Tunnel Safety and Security, Stockholm, Sweden, SP Technical Research Institute Of Sweden, 12-14 March 2008

[63] INGASON, H., APPEL, G., LI, YZ, Large scale fire test using Fixed Fire Fighting System in Runehamar Tunnel, SP Report 2014:32

[64] BLANCHARD, E., BOULET, p., CARLOTTI, P., Capability of a CFD Tool for Assessing a Water Mist System in a Tunnel, 15th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels, pp 717-727, Barcelona, Spain, 18-20 September, 2013

[65] VAARI, j., HOSTIKKA, S., SIKANEN, t., PAAJANEN, A., Numerical Simulations on the Performance of Water-Based Fire Suppression Systems, VTT Technology 54, 2012

[66] Comite europeen de Normalisation Publications, EN 12845 Fixed Firefighting Systems - Automatic Sprinkler Systems - Design, Installation and Maintenance, CEN-CENELEC Management Centre, Avenue Marnix 17 - B-1000 Brussels, 2004 Edition

[67] UPTUN Engineering Guidance for Water Based Fire Fighting Systems for the Protection of Tunnels and Subsurface Facilities, European Commission research project UPTUN, Work Package 2.5, Report R251, August 2006.

[68] WORLD ROAD ASSOCIATION (PIARC), Technical Committee C4 on Road Tunnel Operations, Human factors and road tunnel safety regarding users, 2008R17.

[69] KOELL, M., Single Tunnel and still safe – The Felbertauern Tunnel, 4th International Conference on Tunnel Safety and Ventilation, pp 133-138, Graz, Austria, 21-23 April, 2008

[70] LEUCKER, R., LEISMANN, F.M., Fire Tests for Water Mist Fire Suppression Systems in Road Tunnels, Underground. The Way To The Future, Proceedings Of The World Tunnel Congress, pp 366–375, Geneva, Switzerland, 31 May - 7 June, 2013.

42


[71] LEMAIRE., A.D., MEEUSSEN, V.J.A., Experiments to determine BLEVE-risk and downwind tenability conditions during growth and suppression of real large tunnel fires, Efectis Nederland BV: A TNO Company, March 2008.

[72] TARADA, F., NOORDIJK, L.M., CHEONG, M.K., CHEONG, W.O., LEONG, K.W., The Energy Budget in Suppressed Tunnel Fires, 15th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels, Barcelona, Spain, 18-20 September 2013.

[73] CHAN, E., TARADA, F., Crossing Points, Fire Risk Management Journal, Fire Protection Association, UK, March 2009.

[74] INGASON, H., LI, Y.Z., LÖNNERMARK, A., Handbook of Tunnel Fire Dynamics, chapter 16, pp 403-441, Fire Suppression and Detection in Tunnels, Springer, 2015.

[75] INGASON, H., LI, Y.Z., Technical Trade-Offs Using Fixed Fire Fighting Systems, pp 90-97, 7th International Conference on Tunnel Safety and Ventilation, Graz, Austria, 12-13 May 2014.

[76] INGASON, H., APPEL, G., LI, Y.Z., Large Scale Fire Tests with Fixed Fire Fighting System in Runehamar Tunnel, SP Report, 2014:32, SP Technical Research Institute of Sweden.


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9. GLOSSARY

TERM DEFINITION

Backlayering Where smoke from a fire flows in the direction opposite to the ventilation system airflow. (See also Critical Velocity).

Boiling Liquid Expanding Vapour Explosion(BLEVE)

The explosive release of expanding vapour and boiling liquid following the catastrophic failure, due to an external fire, of a pressure vessel holding a pressure liquefied gas such as LPG (liquefied petroleum gas) or CNG (compressed natural gas). Note: the event may result in fireballs, blast, projectiles and possible toxic vapour cloud. (Abbr. BLEVE).

Compressed Air Foam System

A pressurised water system that allows the addition of compressed air to produce a stream of foam during pumping operations. (Abbr. CAFS).

Computational Fluid Dynamics (CFD)

The use of numerical methods and algorithms to solve and analyse 3-dimensional fluid flow problems. (Abbr. CFD).

Concrete Traffic Barrier

Concrete impact barriers to protect tunnel infrastructure. Note that a New Jersey Barrier (NJB) is a type of Concrete Traffic Barrier. (Abbr. CTB).

Critical VelocityThe velocity of air within a longitudinally ventilated tunnel that creates sufficient airflow to oppose the buoyancy forces of hot smoke from a fire and thereby prevents the smoke from backlayering in the direction opposite to the ventilation system airflow. (Abbr. Vc).

Deluge System An open, FFFS comprising relatively large water droplets activated on a zone-by-zone basis. Note: the operation of the system can be automatic or manual.

Fire Main The primary pipeline providing pressurised fire fighting water (or other fluids) along a tunnel for final distribution to section valves, hydrant valves, and other suppression systems via standpipes.

Heat Release Rate The rate of heat energy output from a fire. (Abbr. HRR).Heavy Goods Vehicle

Heavy Goods Vehicles are trucks and buses where the truck can be a single truck, lorry-trailer combinations, articulated trucks, or semi-trailers. (Abbr. HGV).

Hydrant A coupling connected to a standpipe so that fire hoses can be connected.

K-factor A factor used to calculate the volumetric flow rate of water discharge for each nozzle as a function of nozzle operating pressure.

Probability of Failure on Demand

A value, expressed as a percentage, that indicates the probability of a system failing to respond on demand. It equates to 100% minus the percentage Safety Availability. (Abbr. PFD).

Reliability, Availability, and Maintainability

Reliability, Availability and Maintainability (RAM) is a modelling methodology used to simulate and predict a system’s capabilities for a given configuration in terms of its operation, failure modes and failure rate, maintainability and hence its overall availability. RAMs analysis is used as a comparative tool to compare the performance of different system configurations. (Abbr. RAM).

Section ValveA valve or device that can be activated to open or close the water supply from a fire main to the pipework providing water to a zone downstream. Activation is generally via a control system either automatically or manually. Some jurisdictions may also require activation to be able to occur locally.

Standpipe

A connecting pipe or adaptor that enables water to be delivered from a supply point or main to a point of connection. For fire fighting purposes, the point of connection is generally a hydrant point, sprinkler outlet or section valve. In a tunnel environment the standpipe is dedicated to fire purposes. Standpipes can be either wet or dry.

Water Mist System An open, FFFS comprising relatively fine water droplets activated on a zone-by-zone basis. Note: the operation of the system can be automatic or manual.

Zone A section of tunnel served by a section valve for a deluge of water mist system.

44


10. APPENDICES

APPENDIX 1. QUESTIONNAIRE DATA

A1.1 IntroductionIn 2012, a questionnaire was sent to numerous road tunnel agencies around the world to gather data on the use of FFFS. Responses were received and collated from mid 2012 to early 2014. 52 responses were received and they are believed to provide a representative sample. The output of the questionnaire provides some guidance to those who may seek to use FFFS. The results are presented below.

A1.2 Tunnels without FFFSAlthough there were only eight respondents in this category, the vast majority of road tunnels worldwide have no FFFS installed. As reinforced by the responses, the predominant reasons for not using FFFS are due to the age of the tunnel, in that FFFS were not required at the time of tunnel construction, and there was no advantage seen in the use of FFFS as insufficient data were available in the tunnel community on the benefits and operational criteria to justify its use.

A1.3 Tunnels considering the use of FFFS in the futureReasons for FFFS being considered in the future for the five respondents appears to predominantly be that application of FFFS provides a capital advantage in that some other systems do not need to be provided in the tunnel system with the application of FFFS, and that it is seen that FFFS provide enhanced life safety and protection to the tunnel structure. Insufficient data were available to determine if FFFS of one particular type were preferred. The type of system is generally to be determined by future studies at the particular tunnels noted.

A1.4 Tunnels using water mistThe nine tunnels that responded to the questionnaire use high pressure Water Mist System with a water application rate of between 0.5 to 0.73 l/min/m3. Design fire sizes for this application rate vary from 30 MW to 200 MW. The predominant reasons for using FFFS were for life safety, and protection of the tunnel structure and equipment. It is interesting to note that in most of the tunnels listed, the potential to apply cost offsets for using FFFS was not a relevant determinant for using FFFS.

A1.5 Tunnels using delugeThe 24 tunnels that responded to the questionnaire use Deluge Systems with a water application rate of between 6 to 12 mm/min. Design fire sizes for this application rate vary from 20 MW to 200 MW. Tunnels with a higher design fire size generally had a higher water application rate implying that some consideration was given to the design fire size when selecting the application rate. The predominant reasons for using FFFS were for life safety, and protection of the tunnel structure and equipment. The use of FFFS to offset the cost of implementation of other systems appears to be almost equally split where some choice was available to the tunnel designer (it is noted that the implementation of a Deluge System in Australia is mandatory).

A1.6 Tunnels with other systems installedResponses were received from two tunnels that do not have a Water Mist System or Deluge System (i.e. the system installed is not a system that complies with the limitations listed in chapter 1.2). It is further noted that a number of tunnels that have a Water Mist System or a


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Deluge System installed also have other types of fixed water supply systems including standpipes and hydrants.

Appendices A1.7 to A1.11 page 46 to 57, are presented as tables.

46


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2016R03EN

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ctio

nal (

bi-

dire

ctio

nal d

urin

g m

aint

enan

ce)

LAN

ES P

ER T

UBE

22

23/

42

22

LEN

GTH

(m)

13,9

7284

012

,300

1,09

093

065

8TU

NN

EL S

HA

PER

ecta

ngul

arR

ecta

ngul

arR

ecta

ngul

arR

ecta

ngul

arH

ybrid

Hyb

ridV

ENTI

LATI

ON

SY

STEM

Long

itudi

nal

Full

Tran

sver

seLo

ngitu

dina

lLo

ngitu

dina

lLo

ngitu

dina

lLo

ngitu

dina

lLo

ngitu

dina

l

REA

SON

S FO

R

PLA

NN

ING

TO

IN

STA

LL F

FFS

Man

date

d

a) L

ife sa

fety

; b)

Pro

tect

ion

of th

e tu

nnel

stru

ctur

e an

d es

cape

rout

es;

c) C

ost o

ffse

t for

oth

er

safe

ty sy

stem

s.

a) L

ife sa

fety

; b)

Pro

tect

ion

of th

e tu

nnel

stru

ctur

e.

a) L

ife sa

fety

; b)

Pro

tect

ion

of th

e tu

nnel

stru

ctur

e.

a) L

ife sa

fety

; b)

Pro

tect

ion

of th

e tu

nnel

stru

ctur

e;

c) C

ost o

ffse

t for

oth

er

safe

ty sy

stem

s.

a) L

ife sa

fety

; b)

Pro

tect

ion

of th

e tu

nnel

stru

ctur

e;

c) C

ost o

ffse

t for

oth

er

safe

ty sy

stem

s.

a) L

ife sa

fety

; b)

Pro

tect

ion

of th

e tu

nnel

stru

ctur

e;

c) C

ost o

ffse

t for

oth

er

safe

ty sy

stem

s.

CO

ST O

FFSE

TN

ot a

pplic

able

a) P

assi

ve fi

re

prot

ectio

n;

b) O

ptim

isat

ion

of

vent

ilatio

n sy

stem

; c)

Impr

oved

esc

ape

eg

ress

; d)

Fire

brig

ade

resp

onse

tim

e.

To m

itiga

te th

e ne

ed fo

r pa

ssiv

e fi

re p

rote

ctio

nTo

miti

gate

the

need

for

pass

ive

fire

pro

tect

ion

a) P

assi

ve fi

re

prot

ectio

n;

b) In

crea

se to

ve

ntila

tion

syst

em;

c) F

ire ra

ting

of M

&E

equi

pmen

t; d)

Impr

oved

esc

ape

egre

ss.

a) P

assi

ve fi

re

prot

ectio

n;

b) In

crea

se to

ve

ntila

tion

syst

em;

c) F

ire ra

ting

of M

&E

equi

pmen

t; d)

Impr

oved

esc

ape

egre

ss.

a) P

assi

ve fi

re

prot

ectio

n;

b) In

crea

se to

ve

ntila

tion

syst

em;

c) F

ire ra

ting

of M

&E

equi

pmen

t; d)

Impr

oved

esc

ape

egre

ss.

TYPE

OF

FFFS

PL

AN

NED

TO

BE

USE

DD

elug

e Sy

stem

Wat

er m

ist w

ith A

FFF

extin

guis

hing

med

iaD

elug

e Sy

stem

Del

uge

Syst

emTo

be

dete

rmin

edTo

be

dete

rmin

edTo

be

dete

rmin

ed

WA

TER

SO

URC

ETa

nks

Tank

s

Tank

s with

1 h

our

stor

age

with

con

tinuo

us

dire

ct fe

ed fr

om w

ater

m

ain

Tank

s with

1 h

our

stor

age

with

con

tinuo

us

dire

ct fe

ed fr

om w

ater

m

ain

Tow

n m

ain

with

tank

ba

ck-u

pTo

wn

mai

n w

ith ta

nk

back

-up

Tow

n m

ain

with

tank

ba

ck-u

p

DET

ECTI

ON

M

ETH

OD

Line

ar H

eat D

etec

tion

and

Vid

eo In

cide

nt

Det

ectio

n

Aut

omat

ic In

cide

nt

Det

ectio

n, C

CTV

, Li

near

Hea

t Det

ecto

r; m

anua

lly a

ctiv

ated

on

conf

irm

atio

n of

a fi

re

Aut

omat

ic In

cide

nt

Det

ectio

n, C

CTV

, Li

near

Hea

t Det

ecto

r; m

anua

lly a

ctiv

ated

on

conf

irm

atio

n of

a fi

re

To b

e de

term

ined

To b

e de

term

ined

To b

e de

term

ined

48


A1.

8 T

UN

NE

LS

CO

NSI

DE

RIN

G T

HE

USE

OF

FF

FS I

N T

HE

FU

TU

RE

CO

UN

TR

YA

UST

RA

LIA

AU

STR

IASI

NG

APO

RE

SIN

GA

POR

EU

KU

KU

K

AC

TIVA

TIO

N T

IMES

45 se

cond

s for

tim

e of

de

tect

ion

to d

isch

arge

With

in 4

min

utes

With

in 4

min

utes

MA

X A

NTI

CIP

ATE

D

FIR

E SI

ZE

30 M

W (b

uses

, van

s an

d ca

rs a

re o

nly

allo

wed

to e

nter

the

tunn

el, b

us fi

re si

ze

adop

ted

from

NFP

A

502

2011

Tab

le A

11.5

.1)

150

MW

(HG

Vs

allo

wed

in tu

nnel

but

no

t tra

ilers

and

da

nger

ous g

oods

ve

hicl

es, H

GV

fire

size

ba

sed

on fr

ee b

urni

ng

larg

e sc

ale

fire

test

in

Spai

n co

nduc

ted

by

Sing

apor

e La

nd

Tran

spor

t Aut

horit

y)

DES

IGN

FIR

E SI

ZE50

MW

50 M

W fo

r ven

tilat

ion;

20

0 M

W fo

r str

uctu

re30

MW

for v

entil

atio

n de

sign

100

MW

for v

entil

atio

n de

sign

if de

luge

syst

em

inst

alle

dCA

PITA

L C

OST

EU 1

4 M

MA

INTE

NA

NC

E C

OST

/ Y

EAR

EU 7

00 k


2016R03EN

A1.

9 T

UN

NE

LS

USI

NG

WA

TE

R M

IST

CO

UN

TR

YA

UST

RIA

AU

STR

IAFI

NL

AN

DN

ETH

ER

LA

ND

SN

ETH

ER

LA

ND

SSP

AIN

UK

UK

UK

TUN

NEL

Felb

erta

uern

Mon

a Li

saH

elsi

nki C

ity

Serv

ice

Tunn

elR

oert

unne

lSw

alm

enC

alle

30

Dar

tford

Tyne

- N

BTy

ne -

SB

LOCA

TIO

NM

atre

iLi

nzH

elsi

nki

Roe

rmon

dSw

alm

enM

adrid

Riv

er T

ham

es,

Dar

tford

–

Thur

rock

C

ross

ing

Wal

lsen

dW

alls

end

TRA

FFIC

FLO

WBi

-dire

ctio

nal

Bi-d

irect

iona

lBi

-dire

ctio

nal

Uni

dire

ctio

nal

Uni

dire

ctio

nal

Uni

dire

ctio

nal

Uni

dire

ctio

nal

Uni

dire

ctio

nal

Uni

dire

ctio

nal

LAN

ES P

ER T

UBE

22

22

23

to 4

22

2

LEN

GTH

(m)

5,30

080

02,

200

2,01

542

9Pr

otec

ted

leng

th

= 2,

352

1,43

51,

650

1,50

0

TUN

NEL

SH

APE

Rec

tang

ular

Hor

sesh

oeH

orse

shoe

Rec

tang

ular

Rec

tang

ular

Rec

tang

ular

Hyb

ridH

ybrid

Hyb

ridV

ENTI

LATI

ON

SY

STEM

Fully

tran

sver

seLo

ngitu

dina

lLo

ngitu

dina

lLo

ngitu

dina

lLo

ngitu

dina

lSe

mi-t

rans

vers

eLo

ngitu

dina

l and

se

mi-t

rans

vers

eLo

ngitu

dina

lLo

ngitu

dina

l

REA

SON

S FO

R

INST

ALL

ING

FFF

S

a) P

rote

ctio

n of

th

e tu

nnel

st

ruct

ure;

b)

Tra

ffic

of

Dan

gero

us

Goo

ds in

tunn

el.

a) P

rote

ctio

n of

th

e tu

nnel

st

ruct

ure;

b)

Pro

tect

ion

of

asse

ts b

uilt

over

th

e tu

nnel

(ra

ilway

line

); c)

Tra

ffic

of

Dan

gero

us

Goo

ds in

tunn

el.

a) L

ife sa

fety

; b)

Pro

tect

ion

of

tunn

el st

ruct

ure

and

tunn

el

equi

pmen

t; c)

Pro

tect

ion

of

exte

rnal

traf

fic

netw

ork;

d)

Pro

tect

ion

of

asse

ts b

uilt

over

th

e tu

nnel

; e)

Cos

t off

set f

or

othe

r sys

tem

s.

As a

con

sequ

ence

of

adm

inis

trat

ive

agre

emen

ts a

nd to

se

t up

a pi

lot

prog

ram

to g

ain

expe

rienc

e w

ith

FFFS

.Pr

ovid

e pr

otec

tion

for t

he tu

nnel

st

ruct

ure.

As a

con

sequ

ence

of

adm

inis

trat

ive

agre

emen

ts a

nd to

se

t up

a pi

lot

prog

ram

to g

ain

expe

rienc

e w

ith

FFFS

.Pr

ovid

e pr

otec

tion

for t

he tu

nnel

st

ruct

ure.

a) P

rote

ctio

n of

th

e tu

nnel

st

ruct

ure;

b)

Pro

tect

ion

of

tunn

el

equi

pmen

t.

a) L

ife sa

fety

; b)

Pro

tect

ion

of

the

tunn

el

stru

ctur

e an

d tu

nnel

eq

uipm

ent;

c) C

ost o

ffse

t for

ot

her s

yste

ms.

a) L

ife sa

fety

; b)

Pro

tect

ion

of

the

tunn

el

stru

ctur

e;

c) P

rote

ctio

n of

tu

nnel

eq

uipm

ent.

a) L

ife sa

fety

; b)

Pro

tect

ion

of

the

tunn

el

stru

ctur

e;

c) P

rote

ctio

n of

tu

nnel

eq

uipm

ent.

CO

ST O

FFSE

TN

ot a

pplic

able

Not

app

licab

le

a) O

ptim

ise

vent

ilatio

n sy

stem

; b)

Sav

ings

in

drai

nage

and

w

ater

supp

ly a

s w

ell a

s wat

er

treat

men

t.

Not

app

licab

leN

ot a

pplic

able

Not

app

licab

le

a) P

assi

ve fi

re

prot

ectio

n;

b) O

ptim

isat

ion

of v

entil

atio

n sy

stem

; c)

Impr

oved

es

cape

egr

ess

d) F

ire b

rigad

e re

spon

se ti

me.

Not

app

licab

leN

ot a

pplic

able

TYPE

OF

FFFS

Hig

h pr

essu

re

wat

er m

ist

(30

- 40

bar)

Hig

h pr

essu

re

wat

er m

ist

(30

- 40

bar)

Hig

h pr

essu

re

wat

er m

ist

(80

bar)

Hig

h pr

essu

re

wat

er m

ist

(30

- 40

bar)

Hig

h pr

essu

re

wat

er m

ist

(30

- 40

bar)

Hig

h pr

essu

re

wat

er m

ist

(50

- 140

bar

)

Hig

h pr

essu

re

wat

er m

ist

(45

bar a

t noz

zle)

Hig

h pr

essu

re

wat

er m

ist

(50

bar a

t noz

zle)

Hig

h pr

essu

re

wat

er m

ist

(50

bar a

t noz

zle)

50


A1.

9 T

UN

NE

LS

USI

NG

WA

TE

R M

IST

CO

UN

TR

YA

UST

RIA

AU

STR

IAFI

NL

AN

DN

ETH

ER

LA

ND

SN

ETH

ER

LA

ND

SSP

AIN

UK

UK

UK

WA

TER

SO

URC

ETa

nks

Tow

n M

ain

Tow

n M

ain

Tank

sTa

nks

Tank

sTa

nks

Tank

Tank

SPR

AY

DEN

SITY

(l/m

in/m

3 )0.

780.

700.

500.

78 –

0.8

00.

70 –

0.7

20.

700.

730.

500.

50

ZON

E D

IMEN

SIO

NS

Full

tunn

el w

idth

x

36 m

long

Full

tunn

el w

idth

x

40 m

long

Full

tunn

el w

idth

x

25 -

30 m

long

Full

tunn

el w

idth

x

25 m

long

Full

tunn

el w

idth

x

25 m

long

14 m

x 2

4 m

7 m

x 2

5 m

25 m

long

, wid

th

varia

ble

depe

ndin

g on

tu

nnel

wid

th

25m

long

, wid

th

varia

ble

depe

ndin

g on

tu

nnel

wid

th

SPA

CIN

G O

F D

ISC

HA

RGE

HEA

DS

2 m

2 m

3.5

m2

m2

m3.

2 m

3.57

m2.

8 m

to 3

.6 m

de

pend

ant o

n tu

nnel

sect

ion

2.8

m to

3.6

m

depe

ndan

t on

tunn

el se

ctio

nZO

NES

OPE

RA

TED

SI

MU

LTA

NEO

USL

Y3

32

33

33

33

DU

RA

TIO

N O

F FF

FS

DIS

CH

ARG

E5

hour

s2

hour

s1

hour

1 ho

ur1

hour

1 ho

ur1

hour

DET

ECTI

ON

MET

HO

D

Line

ar H

eat

Det

ectio

n an

d V

ideo

Inci

dent

D

etec

tion

Line

ar H

eat

Det

ectio

nLi

near

Hea

t D

etec

tion

Line

ar H

eat

Det

ectio

n

Line

ar H

eat

Det

ectio

n an

d V

ideo

Inci

dent

D

etec

tion

Line

ar H

eat

Det

ectio

n an

d V

ideo

Inci

dent

D

etec

tion

Line

ar H

eat

Det

ectio

n an

d V

ideo

Inci

dent

D

etec

tion

Con

trolle

d by

SC

AD

A. I

nput

fr

om V

AID

, Hea

t D

etec

tor,

Man

ual

Cal

l Poi

nt,

Tunn

el C

ontro

ller

Con

trolle

d by

SC

AD

A. I

nput

fr

om V

AID

, Hea

t D

etec

tor,

Man

ual

Cal

l Poi

nt,

Tunn

el C

ontro

ller

AC

TIVA

TIO

N T

IMES

(det

ectio

n to

act

ivat

ion

time)

Act

ivat

ion

by

oper

ator

on

dete

ctio

n an

d ve

rific

atio

n

Man

ual

activ

atio

n by

fire

br

igad

e

Man

ual

activ

atio

n

Act

ivat

ion

by

oper

ator

on

dete

ctio

n an

d ve

rific

atio

n

Act

ivat

ion

by

oper

ator

on

dete

ctio

n an

d ve

rific

atio

n

Dis

char

ge is

in

itiat

ed b

y an

in

dica

tion

from

fi

re-f

ight

ers

Man

ual

activ

atio

n

120

seco

nds o

r ea

rlier

if in

itiat

ed

by T

unne

l C

ontro

ller

120

seco

nds o

r ea

rlier

if in

itiat

ed

by T

unne

l C

ontro

ller

AC

TIVA

TIO

N T

IMES

(tim

e fr

om sy

stem

ac

tivat

ion

to d

isch

arge

)10

seco

nds

10 se

cond

s20

– 3

0 se

cond

s10

seco

nds

10 se

cond

s30

seco

nds

App

rox.

60

seco

nds

App

rox.

60

seco

nds

App

rox.

60

seco

nds

MA

X A

NTI

CIP

ATE

D

FIR

E SI

ZE20

0 M

W20

0 M

WO

ne d

eliv

ery

truc

k (m

ax 1

2 m

lo

ng)

200

MW

200

MW

60 M

W10

0 M

W20

0 M

W20

0 M

W

DES

IGN

FIR

E SI

ZE20

0 M

W20

0 M

W20

MW

200

MW

200

MW

30 M

W20

0 M

W20

0 M

W

CO

MM

ISSI

ON

ING

Acc

epta

nce

crite

ria =

VdS

/ IB

S C

ertif

icat

e

Acc

epta

nce

crite

ria =

VdS

/ IB

S C

ertif

icat

e

Des

ign

base

d on

fu

ll sc

ale

fire

te

sts u

nder

take

n as

par

t of t

he

syst

em

deve

lopm

ent

Full

func

tiona

lity

test

Full

func

tiona

lity

test

Func

tiona

lity

test

un

dert

aken

as

wel

l as a

fire

test

to

90

MW

Fire

test

to

45 M

W

unde

rtak

en in

a

test

tunn

el

Fire

test

not

un

dert

aken

. R

esul

ts b

ased

on

resu

lts fr

om

SOLI

T re

sear

ch

proj

ect.

Fire

test

not

un

dert

aken

. R

esul

ts b

ased

on

resu

lts fr

om

SOLI

T re

sear

ch

proj

ect.

CAPI

TAL

CO

STA

ppro

x. 6

M E

UA

ppro

x. 1

.5 M

EU

App

rox.

4.1

M

EUA

ppro

x. 1

5.5

M E

UA

ppro

x. 6

.3 M

EU

App

rox.

5 M

EU

8.1

M G

BP

MA

INTE

NA

NC

E C

OST

/ Y

EAR

30 k

EU

20 k

EU

249

k EU

158

k EU

75 k

EU

With

Tyn

e–SB

, 17

k G

BPW

ith T

yne–

NB

, 17

k G

BP


2016R03EN

A1.

10

Tunn

els u

sing

del

uge

syst

ems

Due

to th

e nu

mbe

r of r

espo

nses

from

tunn

els w

ith D

elug

e Sy

stem

s, th

e da

ta a

re p

rese

nted

in th

ree

tabl

es –

two

for A

ustra

lian

Tunn

els (

tabl

es 5

and

6) a

nd o

ne

for t

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ls in

oth

er c

ount

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roun

d th

e w

orld

(tab

le 7

, pag

e 55

).

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SITY

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SLY

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HO

DFl

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dete

ctor

Line

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eat

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ual

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erat

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ic

Inci

dent

D

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lly

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atio

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fire

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ic In

cide

nt

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n, C

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near

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t de

tect

or; m

anua

lly

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ated

on

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irm

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nt

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ectio

n,

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ibili

ty a

nd

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mea

suri

ng

syst

em

Fran

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e bu

lbs

52


TA

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SIZE

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54


TA

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SIZE

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OM

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n

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ed

from

wat

er m

ain

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SITY

(mm

/min

)6

66

21 (c

urre

ntly

re

view

ing

to re

duce

to

12 fo

llow

ing

larg

e sc

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fire

test

s)

126

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56


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n tim

e)3

min

utes

(aut

omat

ic)

10 to

15

min

utes

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in 4

min

utes

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in 4

min

utes

AC

TIVA

TIO

N T

IMES

(tim

e fr

om sy

stem

ac

tivat

ion

to d

isch

arge

)A

cou

ple

of se

cond

s5

seco

nds

MA

X A

NTI

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ATE

D

FIR

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ZELa

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size

d bu

s10

0 M

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2 ve

hicl

e ca

r or t

ruck

in

cide

nt

200

MW

(HG

Vs

allo

wed

but

not

trai

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an

d da

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ve

hicl

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size

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allo

wed

but

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d da

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DES

IGN

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9 m

2 fire

pan

with

ga

solin

e20

MW

50 M

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vehi

cle

car o

r tru

ck

inci

dent

200

MW

for

vent

ilatio

n de

sign

200

MW

for

vent

ilatio

n de

sign

30 M

W

OTH

ER N

OTE

SH

ydra

nt S

yste

m

inst

alle

d as

wel

l as

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uge

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ING

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test

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re p

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re te

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enFi

re te

st n

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en

Fire

test

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un

dert

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. Fu

nctio

nalit

y te

st

unde

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en.

Fire

test

not

un

dert

aken

. Fu

nctio

nalit

y te

st

unde

rtak

en.

Fire

test

not

un

dert

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. Fu

nctio

nalit

y te

st

unde

rtak

enCA

PITA

L C

OST

800

M Y

EN20

0 M

EU

MA

INTE

NA

NC

E C

OST

/ Y

EAR

8 M

YEN

20 M

USD

4.6

M E

U


2016R03EN

A1.

11 T

UN

NE

LS

WIT

H O

TH

ER

SY

STE

MS

INST

AL

LE

DC

OU

NT

RY

CH

INA

CH

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APPENDIX 2 - TYPES OF SYSTEMS

A2.1 IntroductionAlthough the term FFFS includes all types of fire-fighting systems in tunnels there is a huge variation in the names and capabilities of different systems. Traditional Deluge Systems are those found in Japan and Australia, consisting of conventional deluge nozzles in zones that can be activated either automatically, or by the operator from the tunnel operation control room. Water Mist Systems may also be designed with zones, the same is true for foam systems, although the zone length may differ. As defined in chapters 1.4.1 and 1.4.2, page 4, Deluge System will be used for deluge systems without foam additives, Water Mist System for systems operating at both high and low pressure, and Foam for all foam systems using the addition of air, including High Expansion (Hi-Ex) and Compressed Air Foam Systems (CAF).

A2.2 Deluge SystemsA2.2.1 General DescriptionDeluge Systems consist of open sprinklers or deluge nozzles attached to pipework at the tunnel ceiling. The pipework consists of mains pipes, manifold pipes, feed mains and branch pipes. The sprinklers or nozzles are attached to the branch pipes, which are typically arranged in a uniform pattern at the ceiling to distribute spray to all sections of the roadway. The branch pipes are connected to a feed main which is connected to a section valve. The section valve is mounted on a manifold attached to the mains pipe that is supplied by one or more water reservoirs or fire pump stations. Mains pipes are normally filled with water up to the point of connection to the section valve (wet); therefore the mains pipe and the section valves must be protected against freezing where this climatic condition exists. The section valve separates the wet mains pipe from the empty (dry) feed main and branch pipes supplying the sprinklers or spray nozzles. When the section valve is opened, water flows into the feed main and branch pipes and discharges from the open sprinklers.

Illustration 7 – Section valve arrangement in cross passage © Clem 7, Brisbane, Australia

The branch piping is divided into deluge zones, typically 25 m to 50 m in length, each served by its own section valve. An independent fire detection system that is capable of locating a fire


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accurately is required, so that the section valve serving the zone where the fire is located can be released. The section valve can be opened either automatically by the detection system, or manually by a signal from the tunnel operator. If an incident occurs on the boundary between two deluge zones, both zones will need to be activated. When the section valve opens, water flows into the feed main and branch piping and discharges from all sprinklers or nozzles in that deluge zone. As the deluge nozzle (or sprinkler head) orifices are open, the branch piping is at atmospheric pressure until water is introduced. A deluge system has a time delay between detection of a fire and the discharge of water from the sprinklers or nozzles due to the time required to operate the valve (which will depend on whether activation is automatic or manual) and to fill the branch piping network with water and reach the desired operating pressure.

The system should be designed with sufficient water capacity to allow simultaneous operation of at least two consecutive deluge zones, but depending on the precision provided by the detection system, it may be necessary to design for three operating zones, one in the incident area, and the adjacent upstream and downstream zones. The length of the deluge zones should be coordinated with the pumping capability as well as the fire detection and ventilation zones. Piping should be designed to allow drainage of water from all piping between the section valve and the sprinklers or nozzles after the flow has been stopped.

Deluge Systems are specified based on the area of coverage required. Due to the constraints and configuration of the section valves, this is generally in the order of 300 m2, however, this value varies according to various national and international standards. The width laterally across the tunnel needs to consider where vehicles will end up after a collision. Where Concrete Traffic Barriers (CTBs) are used, the lateral dimension is considered to be from the toe of the CTB to the toe of the opposite CTB. Where low kerbs are present, the width needs to be extended to the tunnel lining. This concurs with recommendations provided in NFPA 502 [20], and current standard installation practice. NFPA 502 [20] states that deluge nozzles should be spaced such that the system coverage extends to the roadway shoulders and if applicable, maintenance and patrol walkways.

The other considerations in the design of deluge systems are the length of the longest vehicle to ensure the entire vehicle is drenched, and the possibility that a vehicle may stop at the interface between two deluge zones. This means that the minimum number of deluge zones that are required to be activated simultaneously for any tunnel is two.

Deluge discharge densities in existing facilities vary between 2.5 mm/min to 12 mm/min. 6 mm/min is used as the basic requirement for Japanese tunnels, 6 mm/min has been used on bus only tunnels in Australia and 7.5 mm/min to 12 mm/min has been used for road tunnels in Australia. The design discharge densities are a minimum and therefore need to be calculated so that they are achieved in the most hydraulically disadvantaged location.

The current minimum duration for deluge discharge is 40 minutes in Japan and 1 hour in Australia. Note that to maintain the required deluge density, any water volume requirement for hydrant operation will need to be added to the deluge requirements.

A2.2.2 Specific Technical InformationThe length of deluge zones typically varies from 25 m to 50 m. Standard deluge nozzles, which typically require a minimum operating pressure of 1.5-5 bar, are used and they discharge a

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uniform pattern of water droplets over the protected area with droplet sizes less than 1-2 mm in diameter. The K-factor of the nozzles is typically 80 l/min/bar1/2. Tests with fires having potential free burning heat release rates in the order of 25 MW to 150 MW have been undertaken with deluge systems [74].

The most suitable length of the deluge zones must be based on the width of the tunnel and the capacity of the water supply. Large zones will reduce the number of control valves but place a higher total water demand [2]. This may mean that at gore areas of the tunnel (i.e. merges and diverges) where the tunnel width increases, the length of the deluge area may need to be decreased to keep to the standard nominal spray area and to keep the water supply requirement manageable. The typical application rates and zone sizes can result in flow demands in the range of 7,500 to 15,000 litres per minute, which can have a significant impact on supply and drainage system requirements [3]. This value is very much dependent on the tunnel width. For example in a 15 m wide tunnel, a density of 10 mm/min, and a two operating deluge zones of 50 m would require 15,000 litres/min. If the tunnel width is 10 m instead, the corresponding flow would be 10,000 litres/min, which is significantly lower.

If an incident occurs on the boundary between two zones, both zones will need to be activated. The type of fire alarm initiating device is selected mainly based on the hazard (e.g. smoke detectors, heat detectors, CCTV or optical flame detectors). The initiation device signals the fire alarm panel, which in turn signals the section valve to open. Activation can also be manual, depending on the fire protection objectives of the system. Manual activation is usually done via an electric or pneumatic fire alarm pull station, which signals the fire alarm panel, which in turn signals the section valve to open. According to the SOLIT guidelines [23], deluge systems may be activated and operated manually or automatically depending on the availability of trained personnel, the risks expected, the type of deluge system, the control systems used and applicable legislation. NFPA 502 [20] recommends that the time delay should not exceed three minutes in order to prevent the development of a major fire.

The UPTUN [26] and SOLIT [23] guidelines recommend that the installation of pumps comply with the manufacturer’s documented requirements. Pumps shall be installed in a dedicated pump room or other designated area. Adequate ventilation and drainage shall be provided. The pump room shall be lockable to prevent access of unauthorized personnel. Deluge System shall be designed to provide at least 110% of the nominal flow required for the most demanding protection area in the tunnel. This shall be calculated at the minimum nozzle pressure as type tested in full scale fire tests. The required flow rate shall be provided by one or more pumps.

According to the SOLIT guidelines [23], the duration time shall be determined in a specific risk analysis for every individual tunnel. The system shall be capable of a minimum activation time of 30 minutes, although longer activation times are normally required. A minimum of 60 minutes shall be used for tunnels longer than 500 m, however, in practice 90 to 120 minutes are probably necessary to account for the response capabilities of the fire department.

A2.2.3 Examples of Deluge SystemsAustraliaAustralia has installed Deluge Systems into its road tunnels since the Sydney Harbour Tunnel was built. This tunnel was opened in 1992. Currently there are 19 tunnels with deluge systems in operation.


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In Australia, a section valve station is generally located every 120 m along the tunnel length. This location coincides with the location of cross passages or egress passages and therefore the valves are located inside a fire rated space. The section valves are designed so that operation is automatic during a fire event but also allows the operator to be able to open and close section valves as required during a fire scenario, especially if the fire moves or spreads.

The deluge zone length can vary but has generally been designed around a deluge zone area of 300 m2 which covers the full width of the roadway. Consequently, the length of the deluge zone can vary according to tunnel width. The system is designed for simultaneous activation of however many zones are required to provide complete coverage of the maximum length vehicle that uses the tunnel plus allowance to cover the possibility that the vehicle may be at the boundary of two zones. Current common practice is to provide a water discharge density of between 7.5 to 10 mm/min in road tunnels. Australia also has some tunnels that are only used by buses. The water discharge density for these tunnels is generally 6 mm/min. In a fire scenario, the system flow rate is designed to operate for 60 minutes at full flow while a number of hydrants operate simultaneously. Pumps and tanks (if required) are duplicated so that no single failure can affect the Deluge System performance.

Activation of the deluge system is usually by manual operation from a remote control room. The operator receives an alarm from one or a number of detection systems such as a Video Automatic Incident Detection (VAID) system, linear heat detection system, other Closed Circuit TV (CCTV) cameras and/or manual alarm calls. On receipt of the alarm, the operator confirms that there is a fire event and activates the Deluge System. Most systems are configured so that on alarm, unless the operator intervenes, the Deluge System activates. However, the operator can initiate the system prior to automatic operation. The operational intent is to activate the Deluge System as soon as possible while the fire is still small (i.e. less than 10-20 MW).

JapanJapan introduced Deluge Systems into its high risk expressway tunnels 45 years ago and currently there are over 120 systems in operation. Different technical solutions are applied, depending on the owner of the tunnel. The Japanese Deluge Systems are designed for 6 mm/min. The pressure at the nozzle location is between 3 and 3.5 bars. There are either 50 m spray zones or 100 m spray zones. Depending on the owner there are different distances between nozzles in each zone. Water reservoir capacity should be designed as 40 minutes for the operation time for two deluge zones (50 m or 100 m) [25]. System design and operation is as follows:

• fire detectors are located on the tunnel side wall at 25 to 50 m spacing within the whole section for initial detection of the fire;

• the fire location is confirmed in the control room by CCTV, at which point the Deluge System is manually activated for a 50 m zone around the seat of the fire until the fire brigade arrives at the fire site; and

• to minimize the risk of fire spread, one additional deluge zone will be activated.Technically the Japanese water and foam sprinkler systems are automatic in design in combination with fire detector and automatic valve control. However, as automatic operation of sprinkler could cause a traffic accident, the tunnel operator must recognize the fire and confirm its existence by CCTV, before starting the sprinkler system. Once the fire has been visually confirmed, the sprinkler system is started manually as quickly as possible [22].

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USAWhile FFFS are not commonly provided in tunnels in the USA, the City of Seattle Fire Department has made it a requirement to install FFFS in road tunnels since the installation of FFFS in the Battery Street Tunnel (State Route 99) in 1954. The Deluge System installed in the Battery Street Tunnel is operated by spot heat detectors which operate weight actuated mechanical valves and are further supported by the provision for manual and remote operation. This is one of the oldest FFFS installations in the world and, even though it is 60 years old, still functions using nearly all of its original infrastructure.

The Seattle Fire Department specifies the use of a ‘positive alarm sequence’ process for FFFS activation. ‘Positive alarm sequence’ provides both automatic activation in the correct zone(s), and allows the tunnel operator the choice of delaying activation while the alarm source is investigated by other sources such as CCTV.

To date, all FFFS installed in the USA are deluge, and in addition to the Battery Street Tunnel, FFFS are installed in:

• Interstate 5 (I5) – Seattle, 0.8 km in 12 lanes (foam deluge) (1988);• Mt Baker Tunnel Interstate 90 (I90) - Seattle, 3.9 km in 3 bores (foam deluge) (1993); • Downtown Seattle Transit Tunnel – Seattle, bus tunnel (deluge) (1992);• Downtown Seattle Transit Tunnel – Seattle, retrofit for the addition of passenger trains (deluge)

(2009); and• Port of Miami Tunnel - Miami (deluge) (2014).

FFFS are also currently being installed, or planned to be installed, in the following projects:

• Presidio Parkway Tunnels – San Francisco (deluge) – estimated completion date 2016;• Virginia Midtown Tunnel – Norfolk (deluge) – estimated completion date 2016;• SR99 Alaska Way Viaduct Replacement – Seattle, 1.6 km stacked tunnel (2 lanes in each

direction) (foam deluge) - estimated completion date 2016;• I-90 (3 bores) 2.5 miles - Seattle (foam deluge) – estimated completion date 2018; and• SR 520 1 mile – Seattle, 6 km (unknown FFFS) – estimated completion date 2022.

SwedenThe Swedish Traffic Administration installed a simplified Deluge System in the Northern Link Tunnel. An improved version of this concept is also planned to be used in the Stockholm Bypass when it will open in 2020. In total, the system will be installed in 50 km of tunnels.

The design is based on considerations regarding simplicity, robustness, investment costs and maintenance issues. To meet these design requirements the system consists of:


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• a single pipe in the centre line of the tunnel ceiling, fitted with two extended coverage nozzles (large K-factor nozzles) directed horizontally towards each of the tunnel walls. The entire cross section of the 14 m wide tunnel is covered with only one pipe. The nozzle used for the Northern Link Tunnel has a K factor of 240 l/min/bar1/2 and the nozzle for the Stockholm Bypass will have a K factor of 360 l/min/bar1/2;

• long sections of 50 m to 75 m (deluge zones) are used and are designed for delivering 5-10 mm/min without the use of any additives to the water. If two sections have to be activated due to a fire between two sections a lower water density is accepted;

• the Deluge System is combined with the fire hydrant system, reducing the standard requirement for two water mains in the tunnel;

• the water supply is obtained by connection to the public water supply, and no additional pumps are required. This means that the discharge time is virtually unlimited;

• thermoplastic coated steel pipes and clamp couplings.

The main purpose of the system is to limit the fire size and prevent fire spread during the evacuation period in congested traffic situations. When the traffic is flowing freely the need for the system is regarded as minor. The system can be manually operated from the traffic control centre based on detection by CCTV, or from the tunnel escape routes where the section valves are located. The system also starts automatically if a heat sensing cable detects high temperatures from a fire. The sprinkler pipes are self-draining due to the risk of freezing. In winter the temperature in the traffic space is expected to drop below -20 °C.

A2.3 Water mist systemsA2.3.1 General DescriptionWater Mist Systems are fundamentally similar to Deluge Systems (i.e. the pipework consists of a water filled mains pipe, manifold, section valves, dry feed main and branch pipes to which the nozzles are attached to provide water to a specific zone). The mains pipe is connected to a water supply and pumps generate the pressure. Water Mist Systems may vary with respect to their working pressures, i.e. low pressure and high pressure systems. The piping or tubing utilized in the system must be designed for the corresponding operating pressure. To protect against plugging of small orifice nozzles, water mist systems utilize corrosion resistant materials such as stainless steel pipe or tubing. The primary difference between the systems is the percentage of smaller droplet sizes, as the droplet size is inversely proportional to the pressure applied, and the momentum of the spray ejected from the nozzles, as spray from high pressure nozzles typically has higher momentum than spray from low pressure nozzles.

The effectiveness of the mist system is based on a strong correlation between spray density, momentum and droplet size. Mist systems are based on volume of coverage. As mist extends to the total volume, the area calculated needs to consider the tunnel width to the wall lining, the zone length, and the tunnel height. As an example, water densities of 0.5 to 1.5 l/min/m3 with different control objectives have been tested and implemented in some relevant projects (A86 in Paris, M30 in Madrid). As an example, for a zone width of 10 m and zone length of 30 m, tunnel height of 6 m and assuming a water density rate of 1 l/min/m3, with 2 zones operating, the above requirements mean that a minimum flow rate of 3,600 l/min is required.

A2.3.2 Specific Technical InformationThe definition given in the UPTUN guidelines [26] states that the general principle of the low pressure water mist system is to produce a fog (or mist) of small water droplets at a nozzle

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pressure of 3-10 bar. The high pressure water mist system produces a fog (or mist) with a mix of different sizes of water droplets at a nozzle pressure of 60-120 bar.

From the Appendix table in the UPTUN document [26], the total water flow rate per 25 m zone for low pressure systems (without additives) is in the range of 221-683 l/min, and for high pressure systems, 140-550 l/min. Note, however, that the total water flow rate depends on the tunnel width, zone length and the number of zones operating. One zone of 25 m in a 10 m wide tunnel, at 2.3 mm/min, would require 575 l/min. Designing for two zones would require a pumping capacity of 1150 l/min (+ 10% of the nominal flow required), and if for three 25 m zones, 1.725 l/min (+ 10%). If the tunnel is more than 10 m wide and the zones longer than 25 m, the hydraulic demand and pump capacity is much higher. The discharge rate for low pressure systems is in the range of 1.1-3.3 mm/min (l/min/m2) and for high pressure systems 0.5-2.3 mm/min. Note that the design application densities are based on a density per unit area of coverage (mm/min). They are sometimes converted to other measures when discussing water mist systems, namely a volumetric density expressed as a flow rate per volume (l/min/m3) by simply dividing mm/min by the ceiling height of the tunnel in metres. This means that densities are identical when expressed in terms of tunnel area, but very different when expressed in terms of volume when comparing two tunnels with the same width, but totally different tunnel heights. The K-factor for a high pressure nozzle can vary between 4.0 - 5.5 l/min/bar1/2. The length of each zone can vary from 20 m to 25 m and up to three zones can be activated at once.

Water Mist Systems use significantly less water than Deluge Systems. On the other hand they require significantly higher pressure, especially the high pressure system. As a result, pipes, tanks and pump capacities can be smaller, and the water demand be lowered. Likewise, drainage volumes can potentially be lowered [10].

The SOLIT guidelines [23] state that a high pressure Water Mist System applies nozzle pressures above 35 bars. Low pressure Water Mist Systems apply nozzle pressure of less than 12 bars. The medium pressure Water Mist Systems apply nozzle pressure between 12-35 bar. Water Mist Systems apply small water droplets as the fire-fighting agent. The diameter of droplets from a water mist nozzle are usually less than 1 mm, leading to a Dv0.90 of 1 mm, meaning that 90% of the volume of the spray consists of droplet sizes of less than 1 mm. NFPA 750 [21] uses a Dv0.99 value instead of a Dv0.90 value to define a water mist.

Centrifugal pumps are typically used for low pressure and medium pressure systems, whereas positive displacement (PD) pumps (or assemblies of PD pumps) are typically used for medium and high pressure systems. The pump capacity is selected to provide at least 110% (+10%) of the nominal flow required for the most demanding protection area in the tunnel. This is calculated at the minimum nozzle pressure as type tested in full scale fire tests. The minimum output capacity for positive displacement pumps, or assemblies of PD pumps, is 90 l/min. The minimum capacity for centrifugal pumps is 750 l/min. The water tank is suitable for providing water for all simultaneously activated sections (typically two or three) with the required flow rate based on the defined minimum period of operation [23].

There are water mist systems available which are designed to share the riser pipe and pump units with the hydrant system.


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A2.3.4 Examples of Water Mist SystemsTyne Tunnel – Newcastle, United KingdomThe Tyne tunnels in the Newcastle upon Tyne region cross beneath the River Tyne linking the town of Jarrow on the south bank with North Shields and Howden on the north side of the Tyne. The crossing consists of a pedestrian and cyclist tunnel opened in 1951 as well as two road tunnels opened in 1967 as part of the A19. The New Tyne Road Tunnel was opened in 2010. The volume of traffic using the tunnel currently amounts to 38,000 vehicles per day with a predicted increase to 43,000 vehicles per day by 2021.

The New Tyne Tunnel project has become a pioneer in the field of tunnel fire fighting in Europe through the decision to install FFFS to suppress fire for protecting a road tunnel 1.7 km in length. It more than conforms to current legislation in the United Kingdom as well as European standards. The decision to install a fire suppression system in the New Tyne Crossing project was reached following a recommendation by experts based on a quantitative risk assessment and a cost benefit analysis [73]. According to the study, the mean benefit-cost ratio for the installation of FFFS was 1.27, primarily through the expected reduction in traffic delays following a fire.

Both the new road tunnel and the original tunnels are fitted with FFFS on a water mist basis. The protected areas are divided into a total of 130 zones each 25 m long. In the event of fire, three neighbouring zones are activated at the same time [24].

Dartford Tunnel, United KingdomThe Dartford River Crossing Tunnels are located some 25 km from the centre of London and link Dartford on the south bank of the Thames with Thurrock on the north side. The Thames crossing as part of the M25 London motorway ring comprises two road tunnels and the Queen Elizabeth II Bridge and is used by around 150,000 vehicles per day. The two tunnels are altogether 1.43 km in length. The first tunnel was opened for traffic in 1963, the second followed in 1981.

The Highways Agency decided to retrofit a stationary high-pressure Water Mist System from 2010 to 2012, to enhance protection for motorists, the service staff, and emergency services in the event of fire [24].

A86 – Paris, FranceThe A86, also known as the super-périphérique or Périphérique de l’Ile-de-France, is a motorway ring around Paris some 78 km in length. The final section completing the ring in the west is designed as a duplex car tunnel with the driving lanes on top of each other and is equipped with FFFS.

The A86 Tunnel’s total length amounts to roughly 10,300 m and it was opened to traffic in 2008. Taking the related connecting tunnels and the two driving levels into account, around 24 km of tunnel bores had to be provided with fire fighting measures. The A86 Tunnel’s special feature is that it possesses a circular cross-section driven by a tunnel boring machine, which is used for two traffic levels. This results in a clear ceiling height for the traffic levels of only 2.55 m and consequently no heavy goods vehicles are allowed to use the tunnel. Three driving lanes are available per traffic level and direction with one-way traffic. The two traffic levels are linked to one another every 200 m by means of stairwells and there is an evacuation route leading into the open every 1,000 m. The tunnel is equipped with a ventilation system, which provides fresh air to the two traffic levels through special air ducts. Air exhaust and fresh air ducts run along the ceiling and in the area below the carriageway.

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The suppression system in the A86 Tunnel, with a total of 850 zones and 16,000 spraying heads, was applied under real conditions for the first time in December 2010, when a car caught fire. The system worked as planned and the tunnel was able to return to ‘busy as usual’ only one and a half hours after the fire broke out. All those involved assessed the findings obtained during this deployment as extremely positive [24].

Felbertauern Tunnel, AustriaThe Felbertauern tunnel, opened in 1967, has a length of 5,300 m and is operated as a single tube tunnel with bi-directional traffic. As this tunnel goes under the main ridge of the Alps it faces quite often high pressure differences between the portals. This results in natural air velocities of 8 to 10 m/s without any support by ventilation or moving vehicles. Such high air velocities pose a high risk should a fire event occur. A fully transverse ventilation system provides sufficient ventilation in normal operation for air quality and smoke extraction for a fire event. As the tunnel was not equipped with a means of egress, the refurbishing process in 2005/2006 focused on improving the safety standard and increasing self-rescue by introducing additional egress methods. Traffic volume is too low to justify the construction of a second tube. Due to the high overburden and the long length of the tunnel, the construction of a parallel running egress gallery was also not considered due to cost.

To improve the safety of the tunnel, the decision was made to use the existing fresh air duct, located above the traffic envelope, as the egress route. At the time, this was a novel solution and required major civil works. Staircases were erected approximately every 230 m to connect the road level with the new egress route.

Illustration 8 – Sketch of tunnel with staircase to the Egress route © Koell M., Single Tunnel and Still Safe - The Felbertauerntunnel:

Proceedings of the 4th Symposium on Tunnel Safety and Ventilation, April 2008 Graz


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One important new safety feature was the installation of a high pressure Water Mist System. This system was intended to reduce the risk to tunnel users by reducing the HRR and size of a fire and to protect the intermediate ceiling, above which the new egress route runs. It therefore fulfils the goals of both life and structure protection. A high pressure Water Mist System was chosen due to its benefits in water consumption and the reduced space requirements. In the event of an incident three adjacent zones, each with a length of 36 m, will be activated. The water mist application rate is approximately 4 l/min/m², which equates to 3,800 l/min in the three activated zones.

Due to challenging environmental conditions in wintertime, the system performance has to be met for temperatures down to -30°C at the portals. Consequently, special frost protection measures as well as stringent requirements on the materials where required [69].

Vielha Tunnel, SpainThe new Vielha Tunnel, opened in December 2007, was built to replace an existing tunnel, which will only be used as an evacuation tunnel and for transporting hazardous goods in the future. The new tunnel is 5.2 km in length, with varying gradients (550 m with +1.7% and 4,550 m with -4.5%). It operates with a two-way, three lane system with a total width of 14 m. The ventilation system operates as a semi-transverse flow system and is divided into four ventilation sections. These are connected to ventilation stations at the portals. Cross passages lead to the original tunnel for evacuation purposes are arranged at 400 m spacings.

The FFFS are solely activated by manual means by the tunnel operations centre via remote control. At present, activation is only foreseen once all tunnel users and the emergency services have vacated the fire zone. In addition, activation of the fire fighting system is coordinated with the fire detection and ventilation system [24].

M30 Tunnel - Madrid, SpainThe M30 forms Madrid’s inner motorway ring and represents one of Europe’s largest urban road tunnel projects undertaken so far and has a length of approximately 56 km. The project was constructed between September 2004 and summer 2007. Parts of the tunnel as well as technical operational rooms are protected by water mist systems [24].

A2.4 Foam SystemsThere are mainly three types of foam systems. A foam Deluge System with injected foam concentrates into the water supply, a High Expansion Foam System (Hi-Ex) and Compressed Air Foam (CAF).

A foam Deluge System is a specific application system, discharging low expansion foam, resulting in a foam spray from the sprinkler. Foam Deluge Systems are effective at controlling fires involving flammable liquid spills in tunnels, but they are also effective on conventional lorry fuel loads [12]. Systems using injected foam concentrates can be both Deluge Systems and Water Mist Systems as described in chapter 1.2, page 3.

The discharge density needed in order to extinguish or control flammable liquid fires using water with a film forming additive is reasonably well established. Information is for example given in NFPA 16, which recommends an average discharge density of 6.5 mm/min. Large scale fire suppression tests in tunnels show good performance of a foam-water sprinkler system. Water and foam additive, 3% AFFF, was pumped from a container to the deluge zone with nozzles.

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Tests show that the effectiveness of the foam deluge system was not negatively affected by a longitudinal ventilation velocity of 4.2 m/s. The test fires were extinguished in less than 30 seconds [13].

Technology involving CAF [14] or Hi-Ex [15] has been tested against both solid and liquid fuel fires. These foam system tests demonstrated a good degree of fire control. As pointed out by Mawhinney [17] neither the CAF nor Hi-Ex systems have been widely accepted for use in tunnels. One reason is uncertainty about the effect of loss of visibility on fire fighting and rescue operations, particularly with Hi-Ex foam.

APPENDIX 3 - MAINTENANCE AND TESTING

A3.1 IntroductionMaintenance of FFFS includes all technical, operational and administrative requirements so that the system performs to the specified performance during its design life. Regular maintenance of the FFFS commences immediately after the initial testing, commissioning and proving of the system.

The design life of the system can be defined as the period from the start of operational use until the system needs total replacement. It should be noted that some components of the system may need to be replaced a number of times during the design life of the total system. For FFFS the design life is typically 20-30 years depending on the materials used.

A3.2 MaintenanceA good maintenance strategy starts with an integral system design to keep user costs during the life cycle as low as possible and minimising potential safety concerns for the tunnel users and the operations personnel. Therefore, maintainability should be part of the specification for FFFS and should be incorporated into the design process. Regular maintenance of FFFS will be needed to meet the performance specifications as well as the reliability and availability demands during the design life of the system. This is done by periodic inspection, testing and maintenance in accordance with the manufacturer’s instructions, and as prescribed in the various national standards if they exist (e.g. recommendations for the frequency of inspection and testing can in standards such as NFPA 750 [21] or EN 12845 [66].

System components should be regularly inspected and tested to verify that they function as intended. Depending on the system design and location of components, this can lead to some unavailability of the tunnel for components that need visual inspection, maintenance or testing. There will generally be significant constraints when the systems in a road tunnel under operation can be maintained. Typically, tunnel maintenance closures take place at night to minimise disruption to traffic. Therefore, maintenance during these hours is only possible for components which are installed inside the traffic envelope. In general, wherever possible, the components of the FFFS should be installed outside the main traffic tube (e.g. section valves in cross passages), or installed in such a way that they minimise traffic disruptions during maintenance activities (e.g. the water main suspended on the wall above one lane so the entire tunnel cross section is not affected). Whenever possible, FFFS components inside the tunnels should be capable of remote testing so that disruption to the traffic is not necessary or is minimal. Given the range of systems installed in most road tunnels, maintenance access for FFFS may depend on what needs to be done for other tunnel systems and elements. Consequently, maintenance access for FFFS


2016R03EN

may influence the design so that the installed system can be maintained to provide a high reliability combined with a high availability.

Parts of FFFS that typically require maintenance are listed below. Note that the list is indicative only and may vary depending on the type of system installed (i.e. Deluge System or Water Mist System). Also, some items listed below may not be incorporated in every system, like additives (e.g. foam) or protection against freezing:

• power supply to the various components;• water supply;• additives; • pumps;• protection against freezing (heating, circulation); • piping system and supports;• motorised and control valves (section valves);• SCADA system including operational control from the control room;• nozzles;• drainage; and• fuel, lubricant, consumables (e.g. in the case of diesel-driven pumps).

General maintenance frequencies for some components are provided next page. As above, the list is indicative only and may vary depending on the type of system installed and by manufacturer.

Maintenance after a fire:

• all yearly maintenance on system parts affected by the fire;• performance test for pressure and flow; and• replacing or cleaning of nozzles, pipes, brackets, etc. affected by the fire.

If the FFFS are to undergo maintenance or are partially not available, relevant stakeholders such as the fire brigade and alarm receiving facility should be informed prior to the FFFS being unavailable. They also should be informed when the FFFS are returned to service.

Special attention should be given to maintenance aspects that could affect the performance of the system such as change in maintenance contractor, process or material changes, structural changes and other relevant changes to the system. These changes should be incorporated in the change management and safety management system of the tunnel owner.

A3.3 Return to service

Before FFFS are returned to service (after regular maintenance, a component failure and replacement, or a fire event) they should be tested to ensure that they are working properly. This can be verified by comparing the specific test results with the original acceptance tests and the previous test results. The extent of verification testing required may vary depending on the reasons why the FFFS were unavailable.

70


TA

BL

E 9

- M

AIN

TE

NA

NC

E A

CT

IVIT

IES

AN

D F

RE

QU

EN

CIE

SFr

eque

ncy

Act

ivity

Wee

kly

Vis

ual i

nspe

ctio

n of

pum

p un

it on

irre

gula

ritie

s, le

akag

es, e

tc.

Mon

thly

Pum

p:•

Pum

p te

st (s

tart

up b

ut w

ithou

t pre

ssur

isin

g th

e m

ain

pipe

s);•

Insp

ectio

n of

wat

er ta

nk, p

ipes

and

bra

cket

s; •

Insp

ectio

n of

wat

er fi

lters

;•

Whe

re c

ombu

stio

n en

gine

driv

en p

umps

are

inst

alle

d, c

heck

leve

l of f

uel t

ank,

mot

or o

il, e

tc.;

• D

rain

ing

cond

ensa

tion

pipe

in e

xhau

st g

as sy

stem

;•

Che

ck st

arte

r bat

tery

stat

us fo

r com

bust

ion

engi

ne d

riven

pum

ps;

• Te

st p

umps

add

itive

s (e.

g. fo

am);

• Te

st a

nti-f

reez

ing

circ

ulat

ion

pum

p;•

Test

(ant

i-fre

ezin

g) tr

ace

heat

ing

syst

em;

• O

pera

tiona

l tes

t sec

tion

valv

es;

• Te

st n

ozzl

es (o

nly

if an

act

ive

com

pone

nt);

and

• V

isua

l ins

pect

ion

of m

ain

pipe

wor

k fo

r mec

hani

cal d

amag

e an

d ot

her a

bnor

mal

ities

.

Bi-a

nnua

lly

Test

ing

of b

atte

ries;

Insp

ect b

atte

ries,

cont

rol p

anel

s, in

terf

ace

equi

pmen

t;M

anua

lly o

pera

te p

ress

ure

rele

ase

valv

es;

Insp

ect i

nitia

lisin

g de

vice

s and

det

ecto

rs;

Insp

ect p

ump

filte

rs a

nd c

lean

/repl

ace;

Insp

ect f

ilter

s ant

i-fre

ezin

g pu

mp

and

clea

n/re

plac

e;Te

st se

ctio

n va

lves

; and

Sam

ple

chec

k on

spar

e pa

rts t

hat s

houl

d be

in st

ock.

Ann

ually

Vis

ual i

nspe

ctio

n of

noz

zle

head

s and

act

ive

spra

ying

in a

ll se

ctio

ns (d

epen

ding

on

the

syst

em a

nd p

artic

ular

ly fo

r lon

g tu

nnel

s, on

e ca

n al

so c

hoos

e to

onl

y in

spec

t a c

erta

in p

erce

ntag

e of

the

nozz

les a

t one

tim

e, o

r at a

diff

eren

t fre

quen

cy e

.g. t

o co

mpl

ete

an in

spec

tion

of a

ll no

zzle

s bi-a

nnua

lly in

stea

d of

ann

ually

);C

heck

wat

er su

pply

qua

lity;

Cha

nge

oil p

ump/

dies

el e

ngin

e;In

spec

t zon

e co

ntro

l val

ves,

clea

n pr

otec

tion

boxe

s;So

ftw

are

test

s (pu

mp

inst

alla

tion)

;So

ftw

are

and

inte

rfac

e te

st c

ontro

l;Te

st se

nsor

com

pone

nts (

leve

l ind

icat

ors,

pres

sure

, tem

pera

ture

); C

heck

mai

n pu

mps

(inc

ludi

ng fr

ost p

rote

ctio

n) a

ccor

ding

to m

anuf

actu

rer’s

spec

ific

atio

ns; a

ndC

heck

all

rese

rvoi

rs fo

r pol

lutio

n an

d w

ater

qua

lity.

5 ye

arly

Che

ckin

g jo

ints

/con

nect

ions

;R

epla

cing

all

high

and

low

pre

ssur

e ho

se c

onne

ctio

ns;

Pres

sure

test

ing

of th

e pi

pe w

ork

(abo

ve n

orm

al o

pera

ting

pres

sure

); an

dA

naly

sing

and

(if n

eces

sary

) rep

lace

men

t of a

dditi

ves.

5-12

yea

rsH

ydro

stat

ic te

st p

ress

ure

cylin

ders

(onl

y w

ater

mis

t).


2016R03EN

Depending on the regulatory requirements in various countries full system tests may be mandated at regular intervals. Notwithstanding regulatory requirements, a yearly full functional test could be done during night-time maintenance closures. This means the total system would be tested from detection to discharge. Tests could include visual tests of the spray behaviour inside the tunnel or removal and detailed testing of the spray pattern of single nozzles for a certain percentage (e.g. 25% in Holland) of the sections equipped with FFFS, or a removal and external inspection of the spray pattern of a percentage of nozzles (e.g. at least 0.5% of all nozzles in Netherlands). The flow and pressure at the most hydraulically demanding location of the test sections should be recorded.

APPENDIX 4 - RESEARCH AND EVALUATION PROGRAMS

A4.1 Test programs

Except for Australia and Japan, FFFS started to have greater recognition after full scale testing was undertaken after several major tunnel fire incidents. These full scale tests showed that FFFS:

• limit the peak fire heat release rate; • prevent the spread of fire from vehicle to vehicle; and• provide a certain level of structural protection.

In addition, the fire incident in the Burnley Tunnel in Australia in March 2007 showed that a Deluge System was effective in allowing the re-opening of the tunnel the next day. This limited the time the facility was closed and hence any potential losses in revenue stream from tolls.

There have been numerous full scale fire tests in recent years as a result of the changing international landscape. Tests of FFFS have a wide range of applications due to the objectives of various entities that perform the tests and the different types of systems (Water Mist or Deluge Systems). Since the use of FFFS for most of the world is a recent shift in thinking and acceptance in the industry, the last 10-15 years has provided a wide range of test programs. A list of these programs follows.

Test programs are sponsored by multiple agencies and frequently do not have similar objectives. Some testing is sponsored by government entities while other test programs are performed by private industry. Some test programs are extended installation tests performed under the direction of the tunnel owner/operator. These separate entities have varying motives for test performance and each test should be reviewed on its individual merits.

Regardless, certain commonalities can be extracted upon reviewing the test programs available. Repeatability of results and similarities in findings are an important take-away from various test programs. This section attempts to consolidate the significant findings of the various test programs.

72


TA

BL

E 1

0 - L

IST

OF

TE

ST P

RO

GR

AM

S

TE

ST P

RO

GR

AM

YE

AR

LO

CA

TIO

NT

YPE

OF

FFFS

WA

TE

R A

PPL

ICA

TIO

N R

AT

E(m

m/m

in u

nles

s not

ed o

ther

wis

e)FU

EL

Swed

en T

-Rex

[63]

20

13R

uneh

amar

, Nor

way

Del

uge

10W

ood

palle

tsSi

ngap

ore

Test

Pro

gram

s [43

] 20

12Sa

n Pe

dro

de A

nes,

Spai

nD

elug

e8

& 1

2W

ood

& p

last

ic p

alle

tsU

nive

rsity

of C

arle

ton

[54]

2009

Nat

iona

l Res

earc

h C

ounc

il C

anad

aD

elug

eVa

ried;

3, 6

, 9, 1

2 &

14

Prop

ane

A73

Tes

ts (w

ater

mis

t) [1

2]20

08R

uneh

amar

, Nor

way

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er m

ist

Palle

ts a

nd p

ool f

ires

M30

, Mad

rid T

est P

rogr

am [4

6] [4

7]20

06Sa

n Pe

dro

de A

nes,

Spai

nH

igh

pres

sure

wat

er m

ist

0.5-

0.72

l/m

in/m

3D

iese

l poo

ls, w

ood

& p

last

ic

palle

ts

Inte

rmed

iate

Sca

le C

ampa

ign

[42]

2006

CST

B, P

aris

Hig

h pr

essu

re w

ater

mis

t0.

4-0.

8 l/m

in/m

3Po

ol fi

re; w

ood

palle

t & w

ood

crib

sA

86, P

aris

Tes

t Pro

gram

[62]

2005

VSH

, Sw

itzer

land

Hig

h pr

essu

re w

ater

mis

t0.

47 l/

min

/m3

Aut

omob

iles

Scal

e Te

sts [

52]

2005

SP, B

oras

, Sw

eden

Del

uge

5-15

equ

ival

ent

Woo

d cr

ibs

A73

Tes

ts (C

AF)

2005

Run

eham

ar, N

orw

ayCA

FN

AW

ood

palle

ts

UPT

UN

[50]

2004

DM

T, G

erm

any

Spri

nkle

r wat

er c

urta

in, h

igh

pres

sure

wat

er m

ist

1400

l/m

in fo

r spr

inkl

er;

8 fo

r low

pre

ssur

e

(150

l/m

in/m

3 )Po

ol fi

re &

woo

d pa

llets

UPT

UN

[59]

2004

IF T

unne

l, N

orw

ayLo

w a

nd h

igh

pres

sure

wat

er

mis

t1.

1-3.

2 fo

r low

pre

ssur

e0.

5-2.

3 fo

r hig

h pr

essu

rePo

ol fi

re &

woo

d pa

llets

A86

Tes

t Pro

gram

[48]

2003

VSH

, Sw

itzer

land

Hig

h pr

essu

re w

ater

mis

t0.

33 –

0.3

5 l/m

in/m

3A

utom

obile

s

2nd

Ben

elux

Tes

ts [4

5]20

01B

enel

ux T

unne

l, Th

e N

ethe

rland

sD

elug

e12

.5Ve

hicl

es lo

aded

with

woo

d pa

llets

Shim

izu

Test

s [53

, 56,

58,

60]

20

01Ja

pan

Del

uge

6Po

ol fi

re, b

us &

pas

seng

er

vehi

cles

Mem

oria

l Tun

nel F

ire V

entil

atio

n Te

st

Prog

ram

[41]

1995

Mem

oria

l Tun

nel,

Wes

t Virg

inia

, U

SAD

elug

e w

/AFF

F8

l/s; w

ater

app

licat

ion

rate

not

reco

rded

#2 d

iese

l poo

l fire

PWR

I Tes

ts [5

1]

1980

Japa

nD

elug

e6

Bus

& p

asse

nger

veh

icle

sO

ffen

egg

[49,

54]

19

65Sw

itzer

land

Del

uge

Not

reco

rded

Pool

fire

sTe

sts w

ithou

t ful

ly p

ublis

hed

data

SOLI

T2 [2

4]20

12Sa

n Pe

dro

de A

nes,

Spai

nH

igh

pres

sure

wat

er m

ist

Not

pub

lishe

dW

ood

palle

ts &

die

sel p

ool f

ire

Mon

t Bla

nc T

ests

[con

fiden

tial]

2012

San

Pedr

o de

Ane

s, Sp

ain

Low

and

hig

h pr

essu

re w

ater

m

ist a

nd d

elug

eU

nkno

wn

HG

V m

ock-

up

SOLI

T1 [6

1]20

06Sa

n Pe

dro

de A

nes,

Spai

nH

igh

pres

sure

wat

er m

ist

Not

pub

lishe

dW

ood

palle

tsEu

ro T

unne

l Tes

ts [c

onfid

entia

l]

2010

San

Pedr

o de

Ane

s, Sp

ain

Hig

h pr

essu

re w

ater

mis

t4.

4W

ood

palle

tsSI

NTE

F –

Run

eham

ar T

ests

[71]

20

07R

uneh

amar

Tun

nel

Wat

er m

ist

Not

pub

lishe

dPa

llets

/poo

l fire

A4.

2 Si

gnif

ican

t fin

ding

s


2016R03EN

A4.2.1 FFFS Prevents the Spread of Fire from One Target to AnotherVarious test programs have established fuel targets as potential combustibles. These targets take various forms. For instance:

• 2nd Benelux fire tests (2001): Target was a full-scale tanker truck which was instrumented to determine heat flux and temperature;

• A86 Test Program (2003): A passenger car vehicle abutted up against the burning vehicle; • University of Carleton (2009): A radiation measurement gauge was used to assess the fire

spread; and• SOLIT2 (2012): A pile of wood pallets was placed downstream of the fire.

The emphasis has been to determine whether a fire will spread from vehicle to target. In all tests, the target fuel did not ignite or would not ignite based on the measured heat flux. FFFS are very successful in preventing the spread of fires from one fuel source to another.

A4.2.2 FFFS Destroys a Stratified Smoke LayerFull scale tests have shown that stratification in a smoke layer will be destroyed in the region of FFFS activation. Every test that has been performed with overhead nozzles has proven this concept. This destratification is usually constrained to the area where the system is applied.

It should be noted that a smoke layer naturally de-stratifies some distance from the fire. Fast growing fires may have destratified smoke typically around 3 minutes after smoke propagation. This phenomenon has been noted in numerous tests and extensively recorded in the Memorial Tunnel Fire Ventilation Test Program [41].

A4.2.3 FFFS Reduce Visibility within the Zone where Activated, Even Without FireVisibility in the region of activation of FFFS is significantly reduced even without a fire event. Test programs have repeatedly shown this effect. Visibility is affected as if there is a heavy downpour of rain.

A4.2.4 Radiation Effects from a Fire are ReducedRadiation is a key contributor to flame spread, endangers tunnel occupants and also prevents fire-fighter access to the immediate region around a fire. Many full scale test programs have measured this phenomenon and have recorded significant reductions in radiation flux with the activation of FFFS.

• 2nd Benelux fire tests (2001);• A86 Test Program (2003); • University of Carleton (2009); and• SOLIT2 (2012).

A4.2.5 Peak Temperatures are Reduced and the Region of Tunnel Impacted by High Heat Effects is Significantly Minimised

FFFS have shown the capacity to reduce peak temperatures directly above the fire, but more significantly, the region of high temperature impact in the tunnel is greatly reduced.

In the University of Carleton work, temperature effects were reduced significantly for a 5 and 10 MW fire HRR. Measurements in SOLIT2 have shown that the temperature of a potential

74


100 MW fire below the tunnel ceiling (0.2 m below ceiling) drops significantly at a location 10 m behind the fire load when the water mist system is started.

A4.2.6 Fire Heat Release Rate can be ReducedA fire can be extinguished, but it depends on the water application rate, the water distribution and the activation time of the system. If a fire is not extinguished with application of FFFS, it may continue to burn but at reduced HRR [23].

A4.2.7 Steam Generation is not Sufficient Enough to be Considered a ThreatOne of the key conclusions from the Offenegg tests in 1965 was that steam generation was a viable threat to life. One of the objectives of the 2nd Benelux Tests was to review this position. Using a deluge system with a 12.5 mm/min flow rate, steam generation was not shown to exist in appreciable quantities. Future fire tests also did not show steam generation, though these were not stated objectives of these tests.

A4.3 Summary Various broad aspects of FFFS based on large scale testing have been reviewed. These are discussed in detail and conclusions given for each aspect. In general, two distinct water application rates were used during full scale testing. Deluge Systems tests normally used a water flow rate of 10 to 12.5 mm/min. High pressure Water Mist Systems normally used a water flow rate of around 4 mm/min. The principal mechanisms of fire suppression using these two types of systems are different. A Deluge System prevents fire growth and reduces fire heat release rate mainly by fuel surface cooling. A Water Mist System mitigates a fire mainly by gas cooling.

The technical benefits of FFFS have been strongly demonstrated via full scale testing. FFFS clearly provide an effective means of managing a fire incident remotely. While FFFS have not been shown to reliably quench or extinguish a fire, the evidence shows that FFFS effectively contain a fire incident and grant the local fire brigade the time and opportunity to approach a fire incident to address it directly. In addition, the region around a fire incident that may be influenced by high temperatures is significantly reduced to the fire location.

Visibility is reduced significantly by the action of FFFS. This may impair egress, but the reduced fire HRR and growth rate also provides additional time for the fleeing motorist who may be wet, but will not be endangered by the tunnel environment.

In most of the full scale tests, the fires were neither extinguished nor fully suppressed, instead conditions around the fire were controlled. Therefore, there is a growing consensus that FFFS only mitigate the fire effects in tunnels. To successfully extinguish a fire, the performance of FFFS needs to be improved.

There are also some arguments that the performance of a Water Mist System is better than a Deluge System. However, under the tested water flow rates, the performance of the Deluge Systems is better on controlling the size of the fire, whereas the Water Mist System is better on thermal management of the environment. Further, it should always be kept in mind that the Deluge Systems and Water Mist Systems discussed here use significantly different water flow rates and droplet characteristics.


2016R03EN

APPENDIX 5 - MODELLING

A5.1 IntroductionComputational Fluid Dynamics (CFD) has been used to accurately model many aspects of tunnel fire safety for more than 20 years. It can be described as a mature tool to gain better insight into smoke movement and assess tenability conditions during a fire.

To install FFFS in a given tunnel, the present state of the art implies performing full-scale fire tests to assess the optimum parameters and effectiveness of FFFS in the event of a fire. However, CFD has great potential for long-term usefulness and might be considered as a valid supplement or even an alternative in the future. This section addresses the essential issue of using CFD for FFFS in tunnels, noting that with current active research this is subject to change.

A5.2 CFD framework for FFFSAs FFFS are discharged inside a tunnel, water droplets mix with the gas flow. The fluid flow in the spraying zone contains therefore two physical phases, the gas phase (e.g. air, smoke) and a liquid phase, the water droplets. To fully describe the state of each phase at any point in the tunnel, two different sets of conservation equations are needed.

For tunnel fire computations, the gas flow is typically described with an Eulerian reference frame methodology and solved through Reynolds Averaged Navier-Stokes (RANS) or Large Eddy Simulation (LES) numerical methods. To account for water droplets’ interaction with the fire conditions, these equations need to be modified to include inter-phase mass, momentum and energy transfer. Various treatments of the dispersed phase can be employed but Lagrangian particle tracking is conventionally used. Individual particle trajectories are computed with equations based on the moving particle location. For a large number of particles, computational parcels can be used where each parcel represents a cloud of many particles with the same characteristics.

A5.3 Input dataFor specific FFFS, manufacturers usually provide the operation pressure and the water flow rate, sometimes expressed as an application rate per unit surface area or volume. When CFD modelling of FFFS is involved, these characteristic parameters are not enough, as the computation requires initial conditions for the particle trajectories. The two main input data are therefore the droplet size distribution and the discharge velocity at the nozzle. The latter can be derived from the operation pressure at the nozzle if the individual nozzle K-factor is provided. The former can only be determined through individual nozzle characterization experiments at laboratory scale.

For a specific nozzle, size distributions are measured at different heights and angles to derive a representative size distribution and a cone angle for the nozzle spray. Numerous optical measurement methods can be used to determine droplet velocity and/or size, but only the Phase Doppler Anemometry (PDA) method is able to measure both at the same time. The method is based on light scattering interferometry and the Doppler effect, and requires a large laser source and multiple photo detectors to assess droplet size and velocity at a given point. The data obtained are processed to provide statistical parameters than can be input into CFD models.

76


A5.4 ValidationThere are a number of definitions of validation and one that is widely accepted defines validation as the process of determining the degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model.

This definition implies that:

• validation involves a process, not a single test or comparison; • it requires an assessment of accuracy, signifying that error and uncertainty are important; and• the context is important, in that different intended applications of the model may have different

requirements.

There have been several full-scale test programs that have been used to perform comparisons of various aspects for CFD modelling. The challenges are in the areas of pyrolysis and combustion modelling, and the spray modelling including wall impingement. The phenomenon of pyrolysis is very complex, however, approximate models can be applied in some scenarios. This part corresponds to the highest uncertainty in CFD modelling of FFFS. Clearly, obtaining accurate solutions is much more challenging than gas-phase calculations for tunnels, not just because the gas and liquid phases must be treated separately but, in addition a number of sub-models such as those accounting for inter-phase mass, momentum and heat transfer have to be carefully selected and validated.

CFD models used for assessing the effect of FFFS on a tunnel fire were developed to handle a number of multiphase flow situations, including gas-liquid, liquid-solid, gas-solid or any combination of the three phases. They may have been verified or even validated for a given context but not for tunnels specifically. Therefore, predictions of the models need to be compared with experimental data from full-scale tests or scaled ones where the scale factor is large enough to have little influence over the key physical phenomena.

The experimental results should thus include relevant physical data, which are of interest to CFD validation, and should capture initial/boundary condition used in the model. A number of different variables in various locations need to be measured. They include HRR, gas temperature, heat flux, gas velocity and concentrations.

A5.5 LimitationsCFD simulations of FFFS become computationally intensive as the number of Lagrangian particles increases. Only transient calculations for the two phases can be performed to properly capture droplet behaviour. The correlations used in inter-phase source terms (e.g. drag relationships) are empirical or semi-empirical. Selecting the models that give an accurate representation of physical reality requires experience on the part of the CFD modeller.

The area that has the most uncertainty in the CFD modelling of water/fire interaction relates to combustion models. Models have difficulty predicting the interaction of droplets on the fuel due to the typical size of a grid cell versus the much smaller scale of the interactions that the model is attempting to predict. Combustion is fairly well understood, but it is difficult to model the full complexity, thus simpler combustion models are generally applied to road tunnel applications.


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Capturing the suppression of a fire using CFD is an evolving field due to the difficulty in modelling the micro-scale interactions among the fuel, oxidant and suppressant. Fire models that use volumetric heat sources have limited provision for modelling flame water interaction as a gross scale must be applied. Manually reducing heat release rate can be accomplished, but this process requires a comprehensive database to develop an empirical relationship between the HRR, and water droplet size and quantity. If the HRR and combustion product yield are well understood a priori, CFD models are able to capture far field effects well (temperature, gas concentration, heat fluxes) [64].

Other approaches to CFD models of FFFS use more detailed combustion models. With the mixture fraction method, a quantity of vaporised fuel is injected into the computation domain from a burning surface. Combustion occurs when the fuel vapour comes into contact with air and sufficient heat. This approach incorporates the physics of a flame, HRR and combustion product yield in more detail than a volumetric approach. The quantity of fuel released from the burning surface in the CFD model can be determined via pyrolysis models or a priori specified heat release rates and fuel parameters. When FFFS are included their effects can be modelled within the pyrolysis model or with an empirical approach. In the pyrolysis model approach, water spray reaches the burning surface and cools it, and the spray also interrupts heat transfer to the surface, thereby slowing fuel pyrolysis and limiting the fire HRR. As for the empirical approach, the amount of heat released from a burning surface is reduced in proportion to the quantity of water reaching the surface [65].

However, both methods rely on empirical parameters. One major challenge with pyrolysis modelling is the difficulty in obtaining relevant material properties. With the empirical approach experiments are conducted to find the relationship between water reaching the burning surface and fire heat release rate, however, this approach models a micro-scale phenomenon using macro-scale observations. Both methods are affected by the wide range of possible fire loads in a tunnel, which have various geometry and fuels. For these reasons, these methods are in their developmental stages and are not typically used in current project design to determine the design fire HRR. There is active and ongoing research to better understand and model the impact of FFFS on the fire [65].

In summary, CFD models with FFFS and a prescribed HRR can be used with a high degree of confidence to predict temperatures, radiative heat flux and smoke behaviour in regions remote from the immediate fire. Methods exist to predict the interaction of FFFS with the HRR. However, these methods involve more complex physics, a greater range of length scales, and they are influenced by uncertainty in the actual fire geometry. As such, the prediction of HRR and combustion products yield using CFD is an evolving area of practice.

APPENDIX 6 - SUSTAINABILITY

Sustainability involves broad concerns about economic, social and environmental objectives. For transport infrastructure, construction and operation increasingly include measures to improve sustainability by reducing environmental impact over the operational lifecycle. Such impacts are typically assessed in terms of carbon emissions. Most efforts to date to assess carbon emissions from facilities focus on normal operating conditions, but some consideration has been given to the influence of fires and FFFS.

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To assess the impact of FFFS, it is important to understand the overall context of carbon emissions. The total carbon emission over the lifecycle of a road tunnel will include the sum of emissions from:

• construction (including materials, transportation and equipment usage);• normal operations and maintenance (notably power consumption);• periodic refurbishments (equipment and transportation for disposal of redundant materials, and

further new materials, transportation and equipment usage); and• tunnel fires (and other incidents), mitigation responses and subsequent repairs.

The benefit of FFFS will be to reduce the fire risks and corresponding carbon emissions. This will be partly negated by the carbon emissions associated with FFFS themselves. To quantify the impact of FFFS, it is therefore necessary to quantify the potential impact of fire risks on the overall carbon emissions over the lifetime of the tunnel. A basic framework for such calculations is illustrated below (adapted from Gritzo [7]).

The total carbon emission (TCE) can be expressed by:

TCE = CEconst + CErefurb + LCEo+m + LCEf

Carbon emissions from construction, CEconst and periodic refurbishment, CErefurb can be considered to be discrete events. These emissions are typically referred to as embodied emissions given their inclusion in the physical elements of the tunnel rather than resulting from tunnels operations.

Emissions from operations and maintenance, LCEo+m can be considered on an annual basis and included in life cycle analysis by multiplying annual rates of emission, ACEo+m by the lifetime of the tunnel:

LCEo+m = ΔTlife × ACEo+m

ACEo+m represents the annual rate of emission for operations and maintenance and is often referred to as the ‘carbon footprint’. Power consumption for tunnel lighting is often an important component of this footprint. The carbon footprint for a fire suppression system would be expected to be relatively small, given its infrequent activation.

LCEf represents carbon emissions associated with the fire risks over the lifetime of the tunnel. These include direct emissions (of carbon dioxide and soot, for example) as well as indirect emissions due to asset damage and release of embodied emissions, both from the tunnel assets and from the goods carried by the vehicles involved in the fire. This can be expressed by:

LCEf = ΔTlife × ff × (mf × ECO2 + Fr × CEemb)

where:

ff annual frequency (fires/year)mf mass of material burned (kg fuel)ECO2 CO2 released per unit material burned (kg CO2/kg fuel)


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Fr fraction of material to be replaced during repairs (-)CEemb total embodied CO2 emissions (kg CO2/kg) [= CEconst + CErefurb]

Reflecting these different contributions, the impact of fire on the lifecycle carbon emissions is illustrated in illustration 9. The impact of FFFS can be measured by the reduction of the fire risk term.

Illustration 9 - Lifecycle carbon emissions © Conceptual Diagram of Contribution of Risk Factors for Lifecycle Carbon Emissions,

Gritzo L.A., Doerr W., Bill R., Ali H., Nong S. and Krasner L., The Influence of Risk Factors on Sustainable Development’ FM Global Research Division

Note that illustration 9 is not to scale. The relative magnitudes of carbon emissions for the different contributions vary widely between tunnels and therefore generic values are not suggested here. The estimation of carbon emissions requires a range of information relating to construction and refurbishment, operations and maintenance. There are various sources of construction industry information, including databases of estimated CO2 emission values for different construction activities. A tailored approach is likely to be required for a road tunnel. When dealing with buildings, carbon emission parameters are typically expressed per unit area, but this would be inappropriate for road tunnels due to their linear nature and the fact that fire risks are principally associated with vehicle traffic.

Another consideration is that a tunnel and its vehicular traffic represent a broad inventory of materials, potential fire loads and fire risks. The risk profile typically encompasses a broad range of potential scenarios (consequences and probabilities) rather than the single set of representative values implied above.

To summarise, the sustainability implications of FFFS can be evaluated in terms of carbon emissions. The benefit of tunnel FFFS will be to reduce the fire risks and corresponding carbon emissions. The significance of this reduction depends on the overall carbon emissions over the lifetime of the tunnel.

Copyright by the World Road Association. All rights reserved.

World Road Association (PIARC)Tour Pascal - 19e étage92055 La Défense cedex, FRANCE

International Standard Book Number 978-2-84060-375-7Frontcover © Marina Coastal Expressway, Singapore

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