aftes · c. larive (cetu) - f. barioz (edf) - jf. douroux (ratp) - d. lesage (cg93) - o. thepot...

Method to assist in asset management for

underground structures

GT14R8A1

www.aftes.asso.fr

ASSOCIATION FRANÇAISE DES TUNNELS ET DE L’ESPACE SOUTERRAIN

Organization member of the AFTES

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AFTES RECOMMENDATION N°GT14.R8A1 M

122 M TUNNELS ET ESPACE SOUTERRAIN - n°236 - Mars/Avril 2013

Recommendations for a method to assist in asset management

for underground structures

AFTES welcomes all suggestions relating to this text.

Recommendation presented by A. RACHER (SIAAP) Leader of Working Group (GT14) and I. BENSLIMANE (S&R) Assistant Leader

This document was drafted in collaboration with:C. LARIVE (CETU) - F. BARIOZ (EDF) - JF. DOUROUX (RATP) - D. LESAGE (CG93) - O. THEPOT (Eau de Paris) - P. THIAUDIERE (SNCF)

This recommendation has been approved by the AFTES Technical Committee following a critical review of the text by:L. CHASSAGNE (RATP) - P. MILLARD - J. PIRAUD - A.ROBERT (CETU) - P. SALVAUDON (CAE) et JJ. SICSOUS

1 - Introduction and aims 123-

2 - Regulatory context 123-

2.1 - Urban transport (metros, the RER, tramways, etc.) . . . . . . .123

2.2 - Rail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123

2.3 - Roads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124

2.4 - Water and wastewater . . . . . . . . . . . . . . . . . . . . . . . . . . . .124

2.5 - Works conducted adjacent to structures . . . . . . . . . . . . . .124

3 - Conditions for the application of an asset-management policy 125-

3.1 - Adequate gathering of initial data . . . . . . . . . . . . . . . . . . . .125

3.2 - Appropriate organisation and resources . . . . . . . . . . . . . . .125

4 - The asset management procedure 126-

4.1 - Knowledge of assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1264.1.1 - Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1264.1.2 - Determining intrinsic characteristics and externalinfluence factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126

4.2 - Evaluating the condition of structures . . . . . . . . . . . . . . . .126

4.3 - Risk studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1274.3.1 - Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1274.3.2 - Risk identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127

4.3.3 - Risk analysis and evaluation . . . . . . . . . . . . . . . . . . . . .1284.3.4 - Decision support and coordinating maintenance activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

4.4 - Implementation of maintenance . . . . . . . . . . . . . . . . . . . . .1284.4.1 - Maintenance policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1284.4.2 - Maintenance plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1294.4.3 - Maintenance performance monitoring . . . . . . . . . . . . .130

5 - Computer resources: GIS and its applications 130-

6 - Conclusion 131-

Appendix 1: IQOA approach for evaluating non-conceded national road network tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . .132

Appendix 2: Rail tunnels managed by SNCF . . . . . . . . . . . . . . . .133

Appendix 3: Metro and RER tunnels managed by RATP . . . . . . . .137

Appendix 4: Hydroelectric dam galleries managed by EDF . . . . .141

Appendix 5: Network of main sewers managed by SIAAP . . . . . .142

Appendix 6: Drainage network managed by Seine Saint-DenisConseil general . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144

122_140RecoGT14uk_Mise en page 1 22/04/13 10:16 Page122

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123

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TUNNELS ET ESPACE SOUTERRAIN - n°236 - Mars/Avril 2013

These recommendations form part of the on-going work by GT14 carried out

in recent years, the 1995 recommendations for structural diagnostics, the 1998

recommendations on renovation using injection, and the 2001 recommenda-

tions on inspection and acceptance of works.

Over the past ten years, AFTES has published many recommendations

relating to studies, works and monitoring of underground works. However, there

has been no document published directed at management agencies to help

them define and implement a rational policy for managing their assets.

In France, underground works constitute assets with a total length of some

10,000 km. These consist mostly of road and rail tunnels, as well as hydraulic

galleries, with total lengths as follows:

• Road tunnels: 320 km

• Rail tunnels: 650 km

• Paris metro and RER tunnels: 270 km

• Hydroelectric development supply galleries: 1,520 km

• Public water supply and drainage galleries: over 5,000 km

• Canals in tunnels: 80 km

• Plus various technical galleries for urban heating, telecoms, etc.

Maintaining these highly diverse and widespread assets involves considerable

challenges covering a number of different areas of activity.

Poorly programmed maintenance works may have a major impact on direct

operation and upkeep costs, as well as inevitably having an effect on the quality

of service provided and, potentially, on individuals and property beyond the

activity itself. It is therefore vital to act at the right time.

The goal of a rational asset management policy is to plan, adjust and supply

resources to the management agency to optimise its interventions in line with

the objectives established for the latter. The policy is designed to provide added

value in terms of knowledge, rationalisation and optimisation of practices

to enable familiarity with the assets and the maintenance of the latter, as

appropriate in terms of operation and preservation.

Most agencies managing significant assets have developed an asset manage-

ment methodology, along with the related tools to implement this; this incor-

porates stages in the evaluation of the condition of structures and the level of

related risks, as well as optimisation of resources to achieve the required level

of service. These types of approach may have been determined following

regulatory obligations or with a view to optimised management.

The purpose of these recommendations is to identify the principal ideas enshri-

ned in the various asset management methods used by such agencies and to

derive a general method that may apply, irrespective of the use of the structures

in question.

They are intended to encourage project owners – the state, local authorities,

road, motorway or rail management agencies, or energy management and

supply bodies – with a rational approach to managing their underground

structure assets.

They relate to all types of accessible underground structures relating to road,

rail and water, built out of any type of material, of any shape, with a minimum

size in excess of 1200 mm, the generally accepted threshold for a structure

being accessible.

AFTES RECOMMENDATION N°GT14.R8A1

1 - Introduction and aims-

2 - Regulatory context-

In order to formulate policy, it is first necessary to identify the regulatory and

contractual provisions that are binding on management agencies in various

fields of activity: rail, road and environmental codes, concession decrees,

and so on.

2.1 - Urban transport (metros, the RER1, tramways, etc.)

In France, Decree 2003-425 of May 9, 2003 concerning the safety of guided

public transport, as amended by the following decrees: 2006-1279 dated

October 19, 2006, 2007-934 dated May 15, 2007, 2008-1307 dated Decem-

ber 11, 2008, 2010-814 dated July 13, 2010 and 2010-1133 dated Sep-

tember 28, 2010, require transport authorities to conduct evaluation of the

safety of the design, construction and operation of urban transport networks

such as metros, RER and tramways. The safety files established in this way

allow operating licences issued by prefectures to be granted. These autho-

risations are valid for 10-year periods, so the safety levels of all transport

systems must be reassessed on a regular basis. Consequently, transport

authorities are required to demonstrate the safety of their transport system,

particularly as regards civil engineering infrastructures. In this case, an asset

monitoring and maintenance policy is necessary in order to ensure the safety

of the transport system as a whole.

2.2 - Rail

Decree no. 97-444 of May 5, 1997 specifies the terms of reference for

Réseau Ferré de France (RFF) missions, as well as the procedures RFF must

follow when acting as project owner for investment work carried out on the

national rail network or when entrusted to third parties.

This decree also specifies the following:

• Each year, RFF must submit an investment programme and its funding

procedures

• RFF either acts as project owner itself or grants project ownership

contracts to persons it appoints, particularly SNCF2, for a given set of works

• RFF defines management goals and principles regarding the operation and

maintenance of technical and safety installations on the national rail net-

work, as well as goals and principles for traffic management and operation

1 RER : Paris Regional Express Network2 SNCF : French National Railway Company


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on the network, with the latter’s missions performed by SNCF.

• RFF provides SNCF with all installation and equipment required to perform

the missions entrusted to it.

• The national rail network is used by rail companies to operate rail transport

services.

• RFF manages its own domain.

Roles are allocated between RFF (as Infrastructure Manager) and SNCF

(Delegated Infrastructure Manager) as follows:

• Maintenance engineering, monitoring and standard upkeep (preventive

maintenance) are carried out by SNCF as part of its mission as Delegated

Infrastructure Manager (Gestionnaire d’Infrastructure Délégué, GID). The

related budget is included in the lump-sum total for the infrastructure

management contract drawn up with RFF.

• Major maintenance work (curative maintenance) also forms part of the

SNCF’s GID mission, on the basis of specific budgets allocated by RFF.

• Upgrading work on tunnels, which qualifies as investments for accounting

purposes, is the subject of a Delegated Project Ownership instruction from

RFF, with specific funding. This must be consistent with the performance

contract agreed between the State and RFF.

Rail infrastructure upkeep policy is governed by a reference document com-

mon to SNCF and RFF, IN3930 (EF 0 E 1) Version 01 dated 08-04-2009.

Monitoring tunnel assets is carried out according to an SNCF internal pro-

cedure (National Instruction IN1256, January 2008). This defines monitoring

cycles and how the condition of national rail network tunnels must be eva-

luated. Following detailed inspections and updates after works, an automatic

ratings system is implemented.

SNCF Engineering provides a report on this every year. This is passed on to

the Delegated Infrastructure Manager and the RFF Project Owner. RFF also

requires monitoring of condition by workpackage, defined depending on the

type of structure (type of lining and line).

2.3 - Roads

For that part of the national road network that is not operated under conces-

sion, regulatory obligations involve two complementary approaches.

The first relates specifically to structures over 300 m in length and concerns

regular safety evaluations. More particularly, it concerns safety installations

and procedures, as well as the mode of operation, and also includes the des-

ign of the structure and more indirectly, the condition of the civil engineering

works.

This evaluation requires a safety file to be compiled to accompany the

request for an operating licence, issued by the Prefect for a 6-year period,

following an opinion from the National Commission for the Evaluation of the

Safety of Road Structures, (Commission Nationale d’Evaluation de la Sécurité

des Ouvrages Routiers, CNESOR).

The second approach is fully dedicated to the monitoring and upkeep of

structures. The circular dated February 16, 2011 concerning the publication

of the new technical instructions for the monitoring and upkeep of bridges

and tunnels (instruction technique pour la surveillance et l’entretien des

ouvrages d’art, ITSEOA) sets out the procedures to be used by decentralised

state departments when carrying out monitoring and upkeep of their tunnel

assets. This instruction is also one component of the reference documents

for Private-Public Partnership (PPP) concession agreements. Other road

maintenance infrastructure project owners may draw on this for inspiration

and adjust it to their own goals and organisations.

The new ITSEOA supersedes the previous one, dated October 19, 1979 and

amended on December 26, 1995. It is supplemented by application guides,

including Fascicle 40, “Tunnels – Génie civil et équipements” (‘Civil engi-

neering and installations in tunnels’). The updated version dated June 2011

deals with particular measures for the monitoring and upkeep of tunnels

with regard to civil engineering and safety and operational installations.

ITSEOA defines organisational principles as well as monitoring and upkeep

actions to be performed (or have been performed). It suggests a three-tier

organisation (cf. § 3.2.2) and indicates inspection frequencies and possible

variations.

Evaluation of civil engineering works also includes a ranking of the condition

of structures. This uses the “IQOA-Tunnels” method (Image de la qualité des

ouvrages d’art appliquée aux tunnels, ‘Bridge and tunnel quality appraisal

as applied to tunnels’). Results can be centralised using LAGORA software

(comprehensive asset management software for bridges and tunnels on the

directly managed national road network), which is currently being finalised

to include tunnels. Each management agency is required to enter and update

all information in this software. Consolidation and exploitation of data is then

carried out nationally by the central technical departments of the ministry

responsible for road infrastructures.

2.4 - Water and wastewater

Decree 2007-675 of May 2, 2007 for application of the water law specifies

implementation of a number of performance indicators for drinking water

and wastewater collection networks, including a “network familiarity and

asset management” index.

The purpose of this index, determined on an annual basis, is to assess the

extent of knowledge of drinking water networks, establish the quality of

infrastructure asset management and monitor changes in this respect.

This index aggregates basic information about the level of cartographic fami-

liarity with networks (existence of a network plan), the level of structural

knowledge (ages, materials, etc.) and the existence or otherwise of a multi-

year maintenance plan.

Based on this index, the law establishes the foundations of minimum man-

datory asset management, binding on all public network management agen-

cies; this will require those who have not yet implemented any such

procedure to procure the means to be familiar with the condition of their ins-

tallations and modes of operation, thus managing these more stringently.

The order dated June 22, 2007 deals in particular with self-monitoring of

wastewater collection networks. It requires project owners to report on the

proper management of the assets to institutional bodies (in particular, the

Water Agency (Agence de l’eau). An annual bonus may be allocated on the

basis of the level of the results achieved compared to the goals set.

2.5 - Works conducted adjacent to structures

Decree 2011-1241 of October 5, 2011 concerning the performance of works

adjacent to underground structures in particular is designed to enhance



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safety on worksites by requiring project owners to be properly familiar with

the location of the assets in order to report on the position of their structures

to stakeholders on the occasion of projected works in the vicinity.

This calls for centralised mapping of all networks to be established, in order

for this to be made available to the various stakeholders and enable them

to clearly identify all networks present within or adjacent to the site perimeter.

This policy should encourage project owners to increase the reliability of

their network mapping and clarify their own responsibilities.


3 - Conditions for the application of an asset management policy-

When an asset management policy is undertaken, exhaustive data about the

assets in question is not always available; the resources required to manage

the processes that must be implemented properly may not be present, either.

3.1 - Adequate gathering of initial data

The durability of a structure depends on a certain number of “explanatory”

parameters. While there are, in theory, a great many of these, experience shows

that some specific basic data is enough to achieve a broad overall definition

of a set of structures and allow an asset management process to be commen-

ced. Based on the structure and the surrounding terrain, these parameters

may be noted, without it being necessary to carry out extensive investigations.

This makes it possible to carry out initial mapping of the existing situation and

provide a broad overview. This method already makes an inspection pro-

gramme a foreseeable reality.

If basic data for all the structures involved is not available, a sample of struc-

tures may be defined using a statistical technique to determine a representative

sample on which investigations and research may be carried out, with the

results extrapolated to the entire group.

3.2 - Appropriate organisation and resources

Setting up asset management may require a degree of organisational change.

Asset management relates to a number of technical aspects such as mainte-

nance and compliance works, functional aspects such as improvements and

taking new needs into account, financial aspects such as cost control and

administrative aspects such as the way departments are organised.

It will affect every stage of maintenance activity. It is a cross-cutting approach

that draws on a wide variety of skills, both within and beyond the body res-

ponsible: inspection, visual inspection, project engineering, performance of

works and controls. This involves a coordinated contribution from a variety of

stakeholders, with differing outlooks, interests and cultures. Consequently, it

calls for the development of a shared culture by all the stakeholders.

This means that the approach involves a project-oriented management aspect,

enabling diverse stakeholders to work together towards a common goal. Such

an approach makes it possible to have an interface between a vertical orga-

nisation (with a number of competent departments that are often isolated and

only have partial information) and a cross-cutting asset management process

which is broad-based, computerised and multi-criteria, founded on a global

view of the activity.

To achieve this, it is necessary to ensure that the necessary human resources

are available to pursue the approach and more particularly, an asset mana-

gement process leader who is responsible for ensuring the success of the

approach. The latter must be able to bring together a single set of goals and

see that these are shared by all stakeholders without preventing the latter from

taking responsibility for the decisions incumbent on them in their respective

fields. An appropriate organisation must be established in which the role of

each player is clearly defined to make them properly accountable.

In this respect, the new Fascicle 40 of the General Technical Specifications

(CCTG) distinguishes three functional levels:

• An operational level – the operations department responsible for monitoring

and upkeep.

• An organisational level – the technical department with responsibility for

organising control, monitoring and inspection operations.

• A decision-making level – the management department.

In addition, it must be ensured there are sufficient technical resources on hand

to deal with the large amount of data to be managed, even if the management

parameters have been simplified. For instance, for assets totalling 50,000 m

and 20 parameters, there will be at least 100,000 pieces of data if data applies

to every ten-metre section of the structure.

A rapid evaluation of the number of parameters to be used should be carried

out to establish the capacity of the IT resources, plus any Geographic Infor-

mation Systems that may be used. AFTES dealt with this topic in 1993 in its

recommendations on ‘Computerisation of archiving and exploitation of data

for tunnels in service’ (L’informatisation de l’archivage et de l’exploitation des

données pour les tunnels en service, GT14R3F1).

Moreover, observations from a large number of management agencies with

an asset management system show that it is vital, when setting up the system,

to implement procedures to update data, since the system will never be reliable

if there is no regular updating process. An annual review of data would appear

to be appropriate.


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The procedure is based on four successive stages that may be developed

to varying degrees, depending on the type of underground structure under

consideration.

• Familiarity with assets: intrinsic characteristics, criticality and factors liable

to influence their condition.

• Familiarity with their condition.

• Evaluation of the risks to their safety and their environment, and the human

and financial consequences of the failure of a structure.

• Implementing maintenance activities that incorporate the criticality of

structures in decision-making in the rationale for decisions and when defi-

ning priorities.

4.1 - Knowledge of assets

4.1.1 - Inventory

The first requirement for knowledge of assets is to have an inventory of the

structures in question. In general, the primary source of information is the

file for the structure that may be found in the archives relating to its construc-

tion and operation. If no archives are available, the starting point should be

a complete, methodical census of all structures, noting basic data such as

their length and size. From the outset, care should be taken to assign codes,

with a view to computer processing of the data and an initial classification

that is simple and quick to perform.

4.1.2 - Determining intrinsic characteristics and externalinfluence factors

Many of the specific intrinsic characteristics of each structure will be com-

mon to all underground structures, irrespective of their purpose, while others

will be closely related to their functionalities and how they are used. Data

may range from simple information that is generally known to more complex

data that may require specific research.

4.1.2.1 - Data common to all structures

Any type of underground structure may be characterised by its mode of

construction and its environmental context. The resulting intrinsic charac-

teristics will be the same irrespective of its purpose; these may be listed as

follows:

• Year of construction

• Mode of construction

• Nature of materials

• Dimensions

• Geological, hydrogeological and geotechnical environment

• History (incidents, works, etc.)

• Adjacent surface and underground structures

4.1.2.2 - Data relating to the use of structures

All structures are built to fulfil one or more functions that call for specific

construction characteristics and related upkeep and operational procedures.

For instance, the specific influence factors for a road or rail tunnel include

the volume of traffic and the mode of operation: one or two-way, authorisation

or prohibition of the transport of hazardous materials.

For a hydroelectric development power tunnel, the factors will include the

difference in water levels in the power plant’s reservoir, the launch of the

hydroelectric power plant, and the rapid, frequent emptying of the structure.

For drainage structures, factors include the risk of pollution of the natural

environment in the event of a leak, the aggressiveness of the waste and the

atmospheric environment.

4.2 - Evaluating the condition of structures

Structures are evaluated using a variety of approaches depending on the

nature, location and purpose of the asset under consideration. Initially, the

evaluation may follow a simple procedure providing basic knowledge of the

condition of structures by means of site visits. Subsequently, a fuller, more

complex approach should be implemented, making use of specialised studies

(inspection, visual inspections and diagnostics1).

In the first case, “basic” visits will cover considerable lengths and allow

initial classification of structures or sections of structures, with a view to

specialised action and/or urgent works if required. In the second case, detai-

led inspections, supplemented when necessary by more detailed visual ins-

pections and a diagnostic, are designed to determine the origin and extent

of defects and identify the potential causes (whether active or passive) of

damage if these are combined in specific configurations.

Strategy for evaluating the condition of structures began to be properly struc-

tured and formalised in regulations for rail networks following the Vierzy

disaster in 1972 (cf. paragraph 2, “regulatory context”). The notion of regular

inspections, triggered systematically even in the absence of any information

about the existence of defects in structures, dates from this time.


4 - Knowledge of assets-

1 Concerning inspections, the principal defects encountered in excavated road tunnels are presented in the ‘Civil Engineering Inspection Guide for Excavated Road Tunnels’, (Guide de l’inspection du Génie Civil destunnels routiers creusés), for covered trenches in the SETRA inspection guide and method guidelines ‘IQOA Structural Evaluation of Covered Trenches’ (IQOA Tranchées couvertes, évaluation des ouvrages), and forunderground structures as a whole, in the ‘Catalogue of Defects in Underground Structures’ drafted by AFTES Working Group 14 (Catalogue des désordres en ouvrages souterrains, GT14R7F1).For visual inspections and diagnostic reports, AFTES recommendations on ‘Visual Inspection Methods for Underground Structures’ (Méthodes d’auscultation des ouvrages souterrains, GT19R2F1) and ‘DiagnosticMethods for Lined Tunnels’ (Méthodes de diagnostic pour les tunnels revêtus, GT14R4F1) may be referred to.


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The frequency and level of detail of visits and inspections should be adapted

depending on the levels of risk relating to the structure, its asset value and

the consequences of any failure. The overall extent of the asset must also

be taken into account. For road and rail tunnels, the level of risk to the safety

of individuals and property is often high, so the schedule of visits and ins-

pections should be highly detailed and systematic (a deterministic approach).

For long networks in uninhabited sites (such as hydraulic galleries), a

probabilistic approach may be incorporated into risk studies.

Irrespective of the method used, tunnel evaluation is based on the following

elements:

• continuous monitoring; this is the responsibility of all operations person-

nel,

• regular monitoring, comprising visits and detailed inspections carried out

by personnel with the skills appropriate for these various types of

intervention,

• occasional interventions, specialised visual inspection and diagnostic work,

defined with regard to specific events in the life of the structure.

Measurement campaigns should be carried out on a regular basis for struc-

tures that require them. They must the analysed and, where possible, be

accompanied by a definition of alert and alarm thresholds. The procedures

used by major project owners are presented in an appendix.

To obtain a summary view of a group of assets, a ranking system is generally

combined with detailed regular inspections, with updates possible on the

basis of diagnostics, specialist maintenance that has been carried out or

major changes to the structure.

This ranking system makes it possible to list structures according to their

pathological condition in terms of safety and longevity, and determine main-

tenance recommendations on this basis.

One example of classification is shown below:

1) no defects: standard maintenance, standard monitoring and upkeep

works.

2) defects that do not compromise safety but decrease the life expectancy

of the structure: preventive maintenance should be envisaged.

3) defects representing a structural risk: curative maintenance should be

scheduled.

4) defects with immediate consequences on the structure’s lifespan, risk of

collapse: emergency works.

4.3 - Risk studies

The notion of risk and the need to manage risks are key concepts with regard

to asset management. In particular, taking into account the level of risk in

maintenance processes for structures and preventing the serious conse-

quences for individuals or property that could arise following a foreseeable

event is essential to improve accurate scheduling of the successive stages

of monitoring, diagnostics and works, in order to optimise costs and to ensure

the activity in question is properly under control.

The ISO 31010 standard cites a number of techniques for studying risks.

Irrespective of the technique used, risks must always be identified. A means

of measuring their likelihood must be determined, as must the degree of

seriousness of potential consequences of any accident or event; there must

also be a means of evaluating risks comparatively in order to rank them and

deal with the situation as appropriate. Any approach, therefore, necessarily

involves a number of techniques.

When a risk study process is commenced for the purposes of asset mana-

gement, the following methodological principles should be observed:

•Adopting simple methods whose functions and parameters are easy to

acquire and measure

• Ensuring that serious accidents will be identified in due time

• Limiting the number of parameters used to rank structures and their envi-

ronment to those that are easily accessible

• Defining a number of levels of action. Recourse to a given level of action

should allow actions for the next level up to be scheduled.

Following on from work by AFTES (cf. in particular recommendations

GT32.R2F1), in this document we have adopted the terminology and

methods defined internationally by the following ISO standards:

- ISO 31000: 2009 (F) – “Management du risque – Principes et lignes

directrices”

- ISO: Guide 73: 2009 (E/F) – “Risk Management – Vocabulary”

4.3.1 - Methods

Risk is defined as the effect of uncertainty on objectives; the level of this

risk is the result of a combination of the likelihood of the event under consi-

deration and its consequences.

In this context, the issue is therefore one of knowing all the factors and

events liable to disrupt the structural condition of each structure and evaluate

their consequences on its condition, functionalities and environment. Once

this has been done, the level of risk for each structure may be determined

by combining the seriousness and likelihood of all the foreseeable events.

On this basis, all structures may be ranked in terms of their level of risk and,

if required, various solutions may be examined and implemented to reduce

their vulnerability.

Consequently, this approach comprises three stages:

• Risk identification. This involves reviewing all the uncertainties and ima-

gining all the positive or negative consequences these might have on the

condition of the structure, its functionalities and its environment.

• Risk analysis (in the strict sense of the term) involves quantifying as well

as possible (or at least qualifying) the likelihood of uncertain events and the

seriousness of their consequences in terms of costs, lead times, safety, envi-

ronmental impact and so on. Since the consequences of an event may affect

various objectives in different ways, the resulting level of risk will vary depen-

ding on the objectives and priorities defined by the project owner.

• Risk evaluation involves comparing the results of the previous analysis

with the acceptability criteria defined by the project owner. It makes it pos-

sible to determine which risks require treatment to bring their seriousness

down to an acceptable level, and the priority for the implementation of these

treatments.

4.3.2 - Risk identification

This initial phase is vital. It involves identifying the factors and events that

may disrupt the structural integrity of the structure and affect its condition,



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functionalities and environment.

No exhaustive list is available. However, one initial approach is to define the

functions that a given structure is to fulfil, such as watertightness, structural

stability, fire safety, transport capacity, and user safety, and for each of these

functions, to list factors and events that may create uncertainty as to the

required levels of performance.

The objectives to be fulfilled may be broken down into three categories:

structural functions, watertightness functions and operational functions.

Secondly, depending on the field in question, these categories may be broken

down further, for instance as follows:

• for roads:

- Structural objective: No deterioration in the stability of the structure or

its environment.

- Operational objective: Traffic is not restricted or interrupted.

- Watertightness objective: No black ice, falling icicles, etc.

• for water supply/drainage:

- Structural objective: No deterioration in the stability of the structure or

its environment).

- Watertightness objectives: No water ingress or leakage.

- Operational objective: Hydraulic capacity and operating conditions, etc.

are maintained.

These checklists should be consolidated with the benefit of experience feed-

back from similar situations.

4.3.3 - Risk analysis and evaluation

This involves defining the causes and consequences of an event with an

impact on the functions and objectives identified above, i.e. determining both

qualitatively and quantitatively the likelihood of the risk and determining its

seriousness, i.e. the extent of possible consequences.

The level of risk (or its criticality) therefore depends on the probability of it

occurring and the intensity of its consequences.

Risk analysis is based on functional analysis of structures and their modes

of failure. Each failure mode is qualified in terms of consequences and occur-

rence; the latter incorporates stable intrinsic causes (level of design, quality

of construction, etc.) and variable causes (deterioration, excess stress, etc.).

The consequences for each failure mode are evaluated by the operator in

terms of the impact it produces with regard to key issues: safety, perfor-

mance, and compliance with regulations.

To carry out this analysis for each event, structure by structure, a matrix with

two inputs (likelihood/consequences) and related ratios may be used, similar

to that shown below:

However it is developed, the ranking must be simple and make it possible to

classify risks in terms of their criticality and their potential to be combined, in

order to deal with the possibility of several events occurring one after the other.

This combinatory approach will eventually result in a determination of

the level of risk for each structure, for each category of risk and overall, and

ultimately to have a criticality map of all assets as a whole. This can then

serve as an aid to scheduling the different stages of maintenance work on

structures: monitoring, inspections, diagnostics and treatments. It should be

noted that diagnostics make it possible to determine the countermeasures

to be implemented to reduce risk, such as operation in degraded mode, or

a short or medium term maintenance programme.

4.3.4 - Decision support and coordinating maintenanceactivities

In the case of significant assets, when confronted with the large amount of

work involved in identification, analysis, evaluation, and deciding on appro-

priate actions in the light of various stress scenarios, management agencies

will have recourse to computer tools when implementing the various stages.

Ultimately, management agencies need a support solution that is integrated

in the decision-making process in order to make properly reasoned choices,

define priorities and choose the right action plans.

4.4 - Implementation of maintenance

4.4.1 - Maintenance policy

The first phase in the maintenance process involves developing the main-

tenance policy; the latter will embody the project owner’s strategic goals in

the form of operational goals; the former enshrines an acceptable level of

risk in terms of the safety of individuals and property, maintaining regulatory

compliance, ensuring proper operation and the longevity of the structures.

4.4.1.1 - Policy content

The maintenance policy defines goals to be achieved as set by the project

owner, specified in terms of risk reduction and observance of obligations to

maintain “in proper working order and condition” as detailed in professional

standards and regulatory requirements.

The policy must define the human and budgetary resources allocated to

achieve these objectives. It may be split up by type of asset (structures,

equipment and installations); the functions and degraded modes of these

types differ. This type of breakdown makes it possible to graduate the level

of maintenance by type and detail different goals for the various dedicated

teams.

This policy must also establish risk management rules, particularly for risks

that may occur in the very short term or “immediately”.

4.4.1.2 - Estimating the resources required for maintenance

The overall quantity of resources required to maintain a set of structures

must be established for a period compatible with the lifespan of the assets

in question. These quantities must make it possible for the maintenance

policy directives to be expressed in terms of needs.


Possible 4 8 12 16

Unlikely 3 6 9 12

Highly unlikely 2 4 6 8

Improbable 1 2 3 4

Slight Significant Highly

significantCatastrophic

Consequences

Like

lihoo

d


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They may be evaluated on an overall basis in terms of the asset value, either

by referring to the usual maintenance ratios for invested capital in the various

businesses involved or by estimating the gap between the condition to be

achieved and the condition determined using the asset condition assessment

tool that has been deployed.

The first method (use of ratios) is simpler but less accurate. It may be seen

as an initial approach that then needs to be analysed using the asset condi-

tion assessment tool in order to check that resources are compatible with

goals on an on-going basis.

It should be noted that these ratios are often lower for non-lined structures

than for civil engineering structures.

The second method makes it possible to have a more precise idea of needs,

since it is based on the known condition of structures. Depending on the

policy goals, various aims may be pursued: improvement in the condition of

the asset if the level of risk or failure rates become unacceptable; mainte-

nance in existing condition; end-of-life reinvestment. Estimation may be car-

ried out on the basis of rough prices by category, such as repairs to support

walls by means of anchoring; construction of a concrete ring; consolidation

and/or repair of waterproofing by injection, etc. Depending on the condition

and the risks evaluated for each asset, a set of rough prices is then applied

on the basis of the target goal and the length to be treated. The method

should be kept simple, without any complex diagnostic investigations. It

should be based solely on the asset condition measurement tool.

In addition, to deal with urgent maintenance needs, for instance in the event

of an incident, reserve resources should be planned, along with precise rules

for implementation and more particularly, the use of countermeasures to

address likely risks in the very short term.

4.4.2 - Maintenance plan

The second phase of the process consists in developing a maintenance plan

that defines the scheduling of monitoring, diagnostic and works operations

and organises the spheres of responsibility of the various stakeholders.

4.4.2.1 - Organisation of responsibilities

In this respect, separating maintenance into two distinct levels is vital.

• The asset management level retains responsibility for preparing mid-to

long-term plans; to do so, it must have enough critical distance and not

be absorbed by the real-time management of operational activities.

• The installation operator level has responsibility for monitoring, minor

maintenance and interim repairs.

Preventive and corrective maintenance can be split between these two levels

as follows.

Project owners must define the limits of responsibility of the operator and

the asset management agency as clearly as possible. Standard NF EN 13306,

which deals with maintenance terminology, may be of use in defining these

limits in terms of the company’s usual vocabulary.

4.4.2.2 - Maintenance plan for which the operator is responsible

In general, the maintenance plan entrusted to the operator relates to pre-

ventive maintenance, for which the financial and human resources are inclu-

ded in operational departments. This must be set up in close collaboration

with the asset management agency, since it will have an effect on the

medium and long-term plans. In order to ensure that the preventive main-

tenance plan – a vital component in the maintenance of structures – is fully

adhered to, a solution to measure the degree to which the activities covered

by this plan are completed should be implemented.

The same teams may conduct both corrective and preventive maintenance

of installations; alternatively, corrective maintenance may be entrusted to

dedicated teams (call-out, site duty, etc.)

4.4.2.3 - Maintenance plan for which the asset managementagency is responsible

The asset management agency’s maintenance plan relates to major works.

Drawing up a prioritised list of maintenance works.

The first step in establishing the medium and long-term maintenance plans

is to draw up an exhaustive list of the works for which the asset management

agency is responsible, both corrective and preventive. Preferably, this list

should be drawn up on the basis of pre-studied interventions (preliminary

design studies), in order to avoid having to decide on works whose need has

not been properly defined.

This means that the list should comprise the following:

• works arising directly from the identification and mapping of risks

• preventive maintenance works.

These works must be categorised and prioritised to ensure decisions are

made on a rational basis using the criteria established for the consequences

and occurrence of total or partial failure of the structure as described in

chapter 4.3 above.

Maintenance plans

In order to manage the maintenance policy’s projected budgets properly,

three complementary maintenance plans should be distinguished: each

has different timescales and degrees of detail depending on the signifi-

cance of the works to be carried out, in line with data from the decision

support tool.


Project owner

Type of maintenance Operator’s responsibility Asset management agency’s responsibility

PreventiveRoutine monitoring and maintenance: upkeep of naturally growing vegetation (including in tunnels), systematic visual inspection, maintenance of waterproofing joints, cleaning drains, testing shutoff controls,measuring leaks, checking signage, etc.

Detailed regular inspection, complete renovation of a waterproofing lining, etc.

CorrectiveInterim repairs: for underground structures, the notion of interim repairs is conceivable but remains somewhat abstract; however, this is more concrete for equipment and installations.

Repairs, reinforcement of a structure following anincident, replacing a shutoff control, etc.


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• The long-term plan works on a ten-year basis. It is destined to plan key

works, including all phases of their progress, studies, purchasing, confi-

guration of structures, execution and acceptance of works, in line with the

budgets planned as part of the maintenance policy. This planning will deal

only with part of the works to be carried out – initially, 50%. Scheduling

of the remaining, less significant works will be carried out in the subse-

quent medium and short term plans, taking into account the experience

from previous decision-making.

• The medium-term plan is directed at 2-5 year scheduling. It is drafted

on the basis of the works decided on when the long-term plan was drawn

up, suitably adjusted for preparation considerations (studies and purcha-

sing), plus medium-scale works. Once again, medium-scale works should

be decided that use up only a part of the envisaged or planned budget –

initially, 20% – in order to allow short-term plans to be developed subse-

quently.

• The short-term plan is directed at one-year scheduling. It is drafted on

the basis of the medium and long-term plans, adding small-scale works.

Contingency margins may either be dealt with wholly by the project owner

or taken on partly by the asset management agency, which will then need

to adjust its resources on the basis of experience feedback.

4.4.3 - Maintenance performance monitoring

The final phase of the maintenance process consists in measuring mainte-

nance performance in order to coordinate the maintenance plan and update

the asset management data.

For civil engineering structures, this measurement should not be based solely

on “availability rate” type indicators. There are two reasons for this:

• failures resulting in a decrease in availability have consequences that are

often major and sometimes unacceptable

• The lifespan of structures is such that there is a major hysteresis effect:

by the time the indicator has begun to indicate something (decreasing

availability), it is extremely difficult to make up the accumulated shortfall

in maintenance.

This means that other indicators should be set up, such as a “completed”/

”pending” ratio. This does not really reflect performance but is useful to

coordinate short and medium-term actions, in the same way that measuring

incidents and/or observations during monitoring is a good indicator to feed

into risk analysis, particularly to evaluate the occurrence of a failure.

Ultimately, the risk analysis tool deployed by the project owner is still the

best maintenance performance indicator. However, evaluation of occurrence

must be sophisticated enough to allow proper anticipation and reduce the

effect of hysteresis.


5 - Computer resources: GIS and its applications-

Any rational maintenance organisation must be based on a reliable information

system that focuses on familiarity with the assets in question.

With the development of geolocation systems, geographic information is now

widely used in asset data management.

A Geographic Information System (GIS) exploits this type of data by

combining the power of database management systems with a spatial

analysis and display interface, making it possible to analyse, map,

review and project complex data. GISs using a range of (often inter-

operable) software are in widespread use in local authorities and com-

panies and have become a standardised tool that is practically

indispensable for exchanging business-specific data between many

different disciplines.

When setting up an asset management solution, network management

agencies often have hardcopy or digital plan archives. These plan

archives are vital, since they form the foundation on which asset data

will be set up. In order for asset management agencies to be on board

and a dedicated application deployed, it is vital that the latter feels

“at home” with the data presented and feels confident right from the

very first elements they see, i.e. the graphical representation of the

networks. It is therefore important to enrich this archive material, for instance

by investing in additional topographic measurements or other techniques in

order to be as familiar as possible with the network.

Figure 1 - Location of SIAAP structures with regard to expansion-contraction contingenciesof clayey and marly areas (BRGM data).


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By using the latest interfaces between CAD and GIS, it is possible to establish

a graphical representation of assets on a GIS, in particular by directly importing

as-built drawings in digital AutoCAD or Microstation format.

It is vital to determine the amount of asset information to be used in the gra-

phical representation very precisely. A summary of asset data may be incor-

porated into a GIS, or at the other extreme, it may include details of every

defect observed during a structure diagnostic. The time and energy needed to

complete and maintain data differs widely between these two scenarios. The

asset management agency must define the scope of the data best suited to

their professional needs, bearing in mind that the richer the database, the

larger the human and financial investment required to maintain it. However,

the interdisciplinary nature of GISs makes it possible to exchange and acquire

data from third parties, thereby enriching knowledge of the environment of

structures more cheaply. Like

any database, a GIS must have

qualified data that is updated as

appropriate to the speed of

change of the data involved.

Using the asset information data-

base they have acquired, asset

management agencies may set

up a module to help analyse asset condition and risks, in order to prioritise

and schedule maintenance.

This means that it is well worth directly incorporating asset data into the

database used by the GIS. This will enable experienced GIS users to exploit

the asset data directly and compare it with other sets of data within the GIS.

Professional data regarding the asset will not be available solely for the use

of the asset management agency, but shared and potentially enriched over

time. If the asset management agency itself is not an experienced GIS user,

the various types of GIS available on the market offer development tools that

make it possible to build an interface that is geared to the needs and knowledge

of specific users. The centralisation of asset data on a collaborative platform

such as a GIS allows asset management agencies to concentrate on maintai-

ning the data rather than on maintaining a specific tool.


Figure 2 - The interface of GUEPARDSasset management software for

SIAAP networks.

6 - Conclusion-

Asset management is a constant concern for project owners seeking to

ensure longevity and continuity of service.

This concern is expressed in a maintenance policy that sets out opera-

tional objectives, the strategic goals of the project owner and ultimately,

the level of acceptability of risks to be observed to ensure the safety of

individuals and property, maintain regulatory compliance, and ensure

the proper working and longevity of structures.

In this regard, the implementation of asset management tools is vital to

structure knowledge of assets and provide management agencies with

a decision support strategy to rationalise their scheduling decisions and

provide proper justification for their budgets.

This approach must be backed by a commensurate level of organisation

and resources. A project-oriented managerial culture must be developed

to allow stakeholders and experts from a wide variety of disciplines to

work together within an open, cross-cutting process that shares the

same culture and overall vision of the activity in question.

The quality and relevance of the data required to develop a reliable and

effective asset management tool must be properly controlled in order to

ensure confidence in the process as a whole. Geographic Information

Systems (GISs) exploit this type of data and have become the norm; they

are invaluable tools for analysing, mapping, projecting and maximising

basic data and the related actions. Their propagation functionalities have

increased considerably even as they have become easier to use, with the

result that they now serve as decision support aids and communication

resources for project owners and their management agencies.


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The IQOA system (‘Image de la qualité des ouvrages d’art’) was set up in 1994

for bridges and tunnels located on the non-conceded national road network.

This tool is designed to assess the condition of assets and define an upkeep

and management policy based on a ranking system. The scheme was extended

to non-conceded state-owned tunnels in 1996 and its application entrusted

to CETU (Tunnels study centre).

Tunnel evaluation is based on the following factors:

• the condition of structures and civil engineering installations: evaluation must

make it possible to assess areas in a uniform condition in terms of defects

affecting the tube’s primary and secondary structures;

• the presence of water: the evaluation must make it possible to assess areas

with water inrushes with regard to risks to users.

Irrespective of the origin and seriousness of the defects, if they have conse-

quences that may compromise the safety of users, the area in question must

be specifically noted in order for it to be dealt with appropriately (note “S”).

Moreover, if the defects affect the stability of the tunnel, the urgent need for

major maintenance must be specified. (Note “U”).

The general evaluation and ranking approach for tunnels using the IQOA

method is based on the following:

• breaking down the tunnel into sections

• evaluation of the component parts of sections or sub-sections

• ranking according to the condition category

• zoning of the tunnel

The tunnel may consist of one or more tubes and ancillary structures, such as

safety galleries, emergency exits, technical premises, shafts, ventilation sta-

tions, etc. The tubes are divided up into sections that are uniform in terms of

structure and geological context. Defined on construction, sections do not vary

over time, except in exceptional circumstances, such as major repairs, for

example.

Sections are evaluated in terms of the condition of civil engineering works and

the presence of water. This evaluation makes it possible to establish “zones”

in the tunnel. A zone is a section that is uniform in terms of the nature and

seriousness of defects and consequently corresponds to a uniform section in

terms of IQOA-Tunnels ranking.

Defined during initial detailed inspection or on first inspection, zones may vary

over time, depending on the progress of defects and observations following

monitoring. Zoning that reflects post-inspection analysis is validated by the

project owner.

Zones and sections are both longitudinal subdivisions of the tube that are

theoretically independent from each other, both of which may be identified by

metre posts.

The IQOA’s “Civil Engineering” ranking comprises 5 classes (1, 2, 2E, 3 and

3U) whose definition takes into account the nature and seriousness of defects

affecting civil engineering structure or installations. An additional note “S” may

be added to any of these classes if the safety of users or third parties is com-

promised. Classes are defined in detail in the new version of “guide de l’ins-

pection du génie civil des tunnels routiers” (‘road tunnel civil engineering

inspection guide’), available from CETU1); Broadly speaking, the classes may

be described as follows:

• class 1: good condition (standard upkeep or cleaning),

• class 2: good condition with some minor defects that do not affect the struc-

ture (regular monitoring and specialised upkeep),

• class 2E: good condition with some evolving minor defects that do not affect

the structure (regular monitoring and urgent specialised upkeep),

• class 3: major structural defects (increased monitoring and non-urgent pro-

tective and/or reinforcement works),

• class 3U: major structural defects, overall stability compromised (increased

monitoring and urgent repairs).

The IQOA’s “Water” ranking comprises 3 classes (1, 2 and 3), the definition of

which takes into account both the degree to which water is present and the

form this takes. As for “Civil Engineering” ranking, the note “S” may be added

to all classes if the safety of users or third parties is compromised. The classes

may briefly be described as follows:

• class 1: no visible water run-off (maintenance of sewer and drainage

networks),

• class 2: slight water run-off: dripping, damp patches (regular monitoring in

addition to maintenance),

• class 3: major water run-off; water under pressure, continuous flow (addi-

tional specialised works).

Evaluation forms an integral part of the detailed inspection review, following

which a ranking pursuant to IQOA procedures is put forward at the organisa-

tional level. This level checks and alters the ranking as required on the basis

of its overall knowledge of its assets and/or information not available on the

date on which the ranking was carried out (e.g. intermittent water inrush). This

is then validated by the decision-making level.

Between two regular detailed inspections and after an evaluation visit,

the organisational level may recommend that the decision-making level alters

rankings if this is justified following works and/or a significant change observed


Appendix 1IQOA approach for evaluating

non-conceded national road network tunnels

EXAMPLES OF PROJECT OWNER METHODS AND APPLICATIONS

1 [email protected] (xx check address)


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during continuous monitoring or annual controls.

Asset management for operating and safety installations is not dealt with here.

However, it may be noted that Fascicle 40 now recommends detailed inspec-

tions for these installations and also defines a ranking system to be applied.

This comprises two scores, one relating to performance (1-4) and one to condi-

tion (1-4). Notes for safety (S) or the impossibility of maintainability (M) may

be added to these scores.

Monitoring civil engineering in tunnels also depends on additional operations

carried out by different, but coordinated personnel.

• Continuous monitoring corresponds to the responsibility of the operations

department to inform the organisational department of any defects, incident

or seasonal/abnormal change (water inrush, falling blocks, etc.).

• The operations department must record all of this information in an on-going

events log, along with all interventions carried out in the tunnel (maintenance,

inspections, etc.).

• An annual visit to all the accessible areas of structures must be planned, in

liaison with installation maintenance and civil engineering upkeep operations,

and organised by the organisational department. The annual inspection com-

prises reports of visits and the summary of the on-going logbook.

• Three years after the initial detailed inspection (IDI) and then every six years

(other things being equal), tunnel monitoring is structured around periodic

detailed inspections (IDP); the only complete visits by competent personnel

for the various structures comprising the tunnel. Project owners are respon-

sible for exploiting and taking into account inspection reports in order to:

- manage the frequency of inspections for each section of the tunnel

- adapt the detailed content of annual visits as appropriate

- organise the maintenance and repair actions2 to be scheduled

- carry out urgent works

- trigger any additional investigations, instrument the tunnel, etc.

• In addition to surveying and analysing defects, inspection reports include

the submission to the project owner of an IQOA ranking for the various zones

of the tunnel. The latter is responsible for the definitive ranking; it may adjust

the proposal in line with additional analysis (comparison with the rest of its

assets, familiarity with the life cycle of the tunnel, etc.).

• Regular measurement campaigns should be carried out on a regular basis

for structures that require them. They must be analysed and, where possible,

be accompanied by a definition of alert and alarm thresholds.


2 The main methods involved are presented in the recommendations of GT 14 on upkeep and repair works (GT14R1F1).

Appendix 2Rail tunnels

1 - Nature and extent of RFF tunnel assets:

In all, the French National Rail Network (Réseau Ferré National, RFN) comprises

1548 tunnels with a total length of 631 km. Of these, only 1378 are in service,

with a total length of 572 km.

Most of these assets are old: 82% of all tunnels in service are over one hundred

years old, with an average age of 124 years (cf. Figure 1).

The length of RFN tunnels in service varies from 12 m (Faubourg des Alyscamps

tunnel on the Arles - Canal line) to 7834 m for the tunnels and trenches on the

Méditerranée HSL as it arrives in Marseille.

These assets are highly varied in nature, with tunnels located throughout the

country and thus situated in a range of different geological environments with

equally differing geometries, as a result of their having been built over a period

of more than one hundred and fifty years.

There are also a range of structural types. Most tunnels use stone blockwork,

while more recent structures use brickwork or poured concrete. Structure is

rarely uniform throughout a single tunnel, with alternations of stone, brick as

well as sprayed concrete reinforcements locally for renovated sections. In addi-

tion, there are over 21 km of tunnels for which the builders simply left bare,

unlined rock. Figure 1 - Bar chart showing tunnel construction dates.

1830

-183

918

40-1

849

1850

-185

918

60- 1

869

1870

-187

918

80-1

889

1890

-189

919

00-1

909

1910

-191

919

20-1

929

1930

-193

919

40-1

949

1950

-195

919

60-1

969

1970

-197

919

80-1

989

1990

-199

920

00-2

009


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Despite the disparate construction methods and types of lining, a number of

uniform features may be observed. Several larger structures may be defined

in terms of their mechanical mode of operation.

• Non-lined tunnels

These tunnels or tunnel sections were excavated in rocky soil that was judged

to be self-stable at the time of construction. The problems over time are the

same as those encountered in rocky trenches. It is nonetheless difficult to carry

out inspection or diagnostic work on these structures. However, attentive moni-

toring can serve to assess any developments and distinguish separate zones

within each tunnel or between multiple tunnels, in order to put forward relevant

programmes of works.

• ‘Umbrella’ arches

Umbrella arch type linings are used in tunnels excavated in soil with good

consistency but that may contain unfavourable fracturing. These are non-load-

bearing structures built to prevent dripping onto the track or to protect the

latter from small blocks of the surrounding terrain falling onto it. Cavities and

overbreak are usually present at the crown.

• Load-bearing structures

These are designed to resist stress from the surrounding terrain, and are used

in tunnels located in soil with mediocre geotechnical characteristics (poor

cohesion and evolving terrain). Linings are usually of a comfortable thickness,

with which soil is in contact, and good constituent materials (good stones,

thick concrete).

2 - Familiarity with tunnel assets

Carrying out relevant tunnel maintenance involves being fully familiar with the

structures in question. This has led to the compilation of files for each structure.

In addition to the basic geometric characteristics (typical cross-sections and

lengths used), they include geological data, the mode of construction, a record

of works conducted since construction (electrification, repairs, war damage,

etc.), a record of damage, visits and detailed inspections, as well as the results

of any additional geotechnical investigations carried out since the tunnel ente-

red service.

This approach is in line with the recommendations of the administrative inquiry

commission appointed by the French Transport Ministry on June 21, 1972, fol-

lowing the accident on June 16 of that year in Vierzy tunnel (official gazette

JO 36, September 25, 1973). Indeed, this inquiry emphasised the importance

of SNCF having highly qualified personnel to monitor and repair tunnels, the

need to seek additional information by conducting investigations (cavities

beyond the outer surface, load on the structure, the presence of groundwater,

etc.) and to keep documents recording the life of the tunnel up to date.

Familiarity with a structure makes it possible to establish a reliable diagnosis

during maintenance carried out during operation, for all types of works:

• Repairs relating to the appearance of defects or upgrading to minimise the

effects of ageing on the structure.

• Adaptation to changes in operation, for instance increasing the size of the

clearance to conform to UIC standards for tunnels for freight transport on

certain major rail corridors.

• Works to comply with regulations as part of the RFN safety programme for

older tunnels, for structures deemed to be critical and tunnels undergoing

structural work over a length in excess of 800 m.

2.1 - Monitoring structures

The condition of tunnels is regularly observed in a number of ways:

• Day-to-day monitoring carried out by all operatives

• Regular scheduled maintenance. This includes:

- Detailed inspection carried out by regional specialists in a six-year cycle,

with the publication of a computerised report including a lining survey and

an evaluation (ranking).

- Intermediate annual visits carried out by dedicated operatives locally,

with comparative observation of the tunnel compared to the survey condi-

tion recorded in the detailed inspection

- An intermediate detailed inspection is scheduled mid-cycle for sensitive

structures, as defined though experience feedback (brickwork and non-

lined zones)

• Additional specialised monitoring carried out by national experts

2.2 - Monitoring tunnel rankings

Tunnel ranking is carried out using an automatic system based on data from

the lining survey, produced during detailed regulatory inspections (see the

principle in Figure 2). The score is a numerical expression of the density of

defects listed for a given surface. Structures in good condition have low scores,

while damaged zones have a high score. Tunnel scores range from 0 to a maxi-

mum of 100 points.

Baseline ranking was carried out in 2006, when all tunnels were ranked.

The results of these updates have been integrated into a tunnel ranking data-

base.

SNCF supplies RFF with an annual review of the tunnel rankings, updated on

the basis of the year’s inspections (approximately 16% of tunnels annually)

and re-evaluation of tunnels after works.


Figure 2 - Outline of tunnel rankings.


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Noteworthy features include changes in the average rank for the assets (see

Figure 3).

Changes in the average rank are the result of two opposing phenomena. On

the one hand, deterioration in linings, which pushes the ranking up, and on

the other hand, repair works, bringing it down.

The increase in the average ranking shows that defects are appearing or

worsening faster than they are being dealt with by repairs, with a resulting

overall decrease in the condition of the assets.

The increase in major upgrading funds granted by RFF in recent years has

slowed the ageing of the assets (see Figure 3).

One way the most damaged tunnels are identified is by looking at the ran-

kings. In addition, inspectors from SNCF Engineering’s Tunnels division exa-

mine some 100 RFN tunnels annually, at the request of local stakeholders

as part of tunnel monitoring or specific expert appraisals, or at the request

of the acting project owner to validate requests for funding as part of their

programme management.

3 - Maintenance of rail tunnels

Roles are allocated between RFF (as Infrastructure Manager) and SNCF

(Delegated Infrastructure Manager) as follows:

• Maintenance engineering, monitoring and standard upkeep (preventive

maintenance) are carried out by SNCF as part of its mission as Delegated

Infrastructure Manager (Gestionnaire d’Infrastructure Délégué, GID). The

related budget is included in the lump-sum total for the infrastructure

management contract drawn up with RFF.

• Major maintenance work (curative maintenance) also forms part of the

SNCF’s GID mission, on the basis of specific budgets allocated by RFF.

• Upgrading work on tunnels, which qualifies as investment for accounting

purposes, is the subject of a Delegated Project Ownership instruction from

RFF, with specific funding.

3.1 - Preventive maintenance

These works, also known as standard upkeep, correspond to work which is

vital but of relatively minor significance. These works are specified and car-

ried out at the local level.

Regular work of this nature, carried out preventively in close liaison with

monitoring, should make it possible to delay the need for major works whilst

preserving normal operating conditions.

Such work generally needs relatively little resources or technical capabilities

and relates mainly to the upkeep of water drainage and discharge, occasional

repointing, adjusting stonework, weeding around tunnel heads, and upkeep

and renewal of signalling components.


Figure 3 - Changes to the average ranking of the condition of all assets.

Figure 4 - Rejointing in progress.

Figure 5 - Water curing underway from a truck fixed on a flat wagon.

3.2 - Curative maintenance

This type of work is funded from the major maintenance budget; the related

study work is incumbent on the regional level. This work is designed to enable

structures to provide the level of service for which they have been built or

adapted. It should maintain or restore the load-bearing capacities of structures

following limited extension alterations that might lead to the collapse of the

tunnel. Identification of such structures is carried out during the course of

monitoring operations.

Work comprises rejointing and partial repair of blockwork, as well as the

creation or restoration of drainage and repair of tunnel heads (blockwork and

waterproofing).

Figure 6 - Repairingblockwork as part ofmajor maintenance.


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3.3 - Tunnel upgrading works

Tunnel upgrading work as part of a maintenance policy comprises a number

of aspects, validated by the Ponts et Chaussées 1994 audit.

• A corrective treatment aspect, designed to remedy irreversible defects,

• A preventive renovation aspect for sensitive structures identified by main-

tenance experts and confirmed by incident feedback,

• An additional aspect dealing with tunnel safety is also implemented for cer-

tain tunnels.

3.3.1 - Corrective treatment

The objective is to remove the most damaged parts of tunnels and progres-

sively reduce the number of other damaged sections, irrespective of the type

of structure involved. The expectation is that during implementation of this

programme, there will be a significant reduction in the number of incidents.

Identification of these tunnels is carried out on the basis of the ranking

results.

• Initially, renovation will relate to sections of tunnel with a condition ranking

of over 60.

• Secondly, this renovation will deal with tunnels with condition rankings of

between 40 and 60 points.

• This corrective aspect will also involve renovating damaged foundations,

sewers and drainage systems, working on an average length of 500 m per

year.

All of these works are funded from a national investment budget; studies

are carried out or validated by the SNCF National Engineering Dept.

3.3.2 - Preventive renovation works One aspect of the maintenance policy involves removal of sensitive structures

(brickwork or non-lined rock tunnels) on all passenger lines within a given

timeframe. At present, preventive renovation is not planned for lines that do

not carry passengers.


Figure 7 - Major reinforcementsusing steel rings ‘surrounded’ byconcrete.

Figure 8 - Reinforcement with a sprayed concrete re-lining to provideadditional thickness.

Figure 9 - Renovation of theoriginal brick liningusing a ribbed shellmade of sprayedconcrete.

Figure 10 - Re-lining an older,unlined zone with a shell of sprayedconcrete.

3.3.3 - Safety in tunnels

The aim here is to improve tunnel safety in order to ensure the safety of

maintenance personnel as well as to facilitate self-evacuation and the inter-

vention of rescue services in the event of an accident or train in distress in

a tunnel.

This work is currently being carried out alongside the upgrading works (cor-

rective and preventive renovation) on tunnels longer than 800 m, in line with

recommendations defined by RFF.

4 - Taking clearances into account

The historic nature of the assets and the tendency for rolling stock dimen-

sions to increase have meant that networks have had to deal with tunnel

dimensions. For instance, the UIC’s GB1 clearance standard comprises 35%

more surface area than that in force around 1863, at the time of the Second

Empire.

What is more, tunnel clearances are not stable since they varies depending

on how tracks on ballast are maintained. Packing and aligning the longitu-

dinal profile leads to the track being raised slightly each time, while route

rectification results in the track shifting sideways. The cumulative effect of

these small shifts ends up gradually reducing the total clearance in the tunnel.

Prior to any maintenance operations, it is therefore vital to check that these

are feasible with respect to the load clearances in force on the line.


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Various types of measurement equipment are available to carry out profile

surveying, and specific software has been developed to carry out geometrical

studies that simulate the future situation and incorporate track maintenance

margins.

In the event of major maintenance requiring the load-bearing capacity of the

lining to be increased by re-lining, internal tunnel geometry considerations

may result in a number of outcomes:

• Adding the re-lining to the thickness if there is plenty of clearance,

• Altering the track level to adjust to irregularities in the inner surface

geometry as well as possible,

• Lowering the track in order to keep work on the crown to a minimum,

• Carrying out work on the old lining by partially inserting the new structure

into it.

A combination of these possibilities may be used to optimise maintenance,

especially for narrower tunnels.

5 - Upgrades programmes

Upgrading policy was long based on monitoring and corrective treatment.

SNCF GID and RFF are now turning more towards a preventive maintenance

policy for tunnels with brickwork and non-lined zones, with an increase in

the number of proposed works and upgrading being planned over a longer

period of time.

Upgrading is scheduled over a period of six years; in theory, the short-term

2-3 year programme has been fixed definitively. Proposals of works more

than six years ahead are referred to as being “emergent”.

Research into the operation and behaviour of underground structures and

the overall processes of evolution and deterioration depending on the type

of lining have made it possible to identify at-risk categories of structure. This

research makes it possible to identify groups of tunnels that in theory will

require maintenance works, but is not sufficient in and of itself to organise

works scheduling.

To identify and prioritise tunnels for upgrading, the current policy being imple-

mented together with RFF is based on “emergent” cases.

The infrastructure management agency is constantly informed of potential

new works via the expert appraisals produced following tunnel inspections.

The expert’s conclusions are recorded in a database that can be used to

monitor scheduled works.

Using this database, “emergent” proposals and their case-by-case analysis

allows an upgrading programme to be drawn up.

The multiyear schedule must be adjusted depending on operational consi-

derations and available funding.

All projects in excess of €2 million are submitted for approval to RFF right

from the launch phase.

6 - Using condition indicators to monitor policy

The policy monitoring called for by RFF is carried out on the basis of condition

indicators developed by SNCF Engineering. These indicators break down

tunnel assets into batches based on traffic density (UIC group) and the types

of lining. The principal statistical data for each lot is specified.

By comparing the indicators between two periods, changes in the various

batches can be analysed, including improvements following the renovation

of multiple tunnels on the same route.

Together with inspection and visual inspection of tunnels, these indicators

make it possible to ensure the upgrading policy is coherent and to monitor

how the policy is being implemented. They can reveal developments that

had not hitherto been envisaged and thus enable policy to be adjusted accor-

dingly.


Appendix 3RATP underground structures

Essentially, RATP’s asset management method is based on the following:

• Updating a list of structures (identification, location, description and nature

of the structure, structure file);

• Planning of visits and inspections, gathering data as to the condition of the

assets;

• Management of gathered data in a database (traceability): health, significant

events;

• Planning of works including ranking of the observed structural condition of

these structures;

• A maintenance policy that is expressed in terms of a Maintenance Master

Plan (Schéma Directeur de Maintenance, SDM) and a multiyear investment

programme that details the policy for works over the next five years, as well

as a twelve-year forecast.

1 - RATP underground assets

Underground works and covered trenches cover a total of some 270 km divided

between Metro, RER and Orly Val lines, with nine passages beneath rivers. In

addition, there are over 100 km of access corridors and almost 42,000 m2 of

ticket halls.


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Several million users pass through all these places daily. Fifty percent of the

metro assets are around one hundred years old (1921 or earlier)

These assets are in a highly urbanised environment and interact with a large

number of other networks.

Most underground structures are one of the following types:

• Masonry arch tunnels

Eighty percent of the underground assets belonging to the metro are masonry

tunnels. Built mostly between 1900 and 1939, these tunnels are very uniform

both in terms of construction methods (the Franco-Belgian method) and the

materials used (millstone grit and cement concrete).

• Steel covered trenches

Steel covered trenches were widely used between 1900 and 1913 in the

construction of the metro, in areas where there was not enough overburden

to build masonry tunnels underground. In this case the structure consists of a

raft foundation supporting steel beams, with brickwork jack arch infills.

• Reinforced concrete structures

Tentative use was made of reinforced concrete structures for some access

points when the metro was first built. Use was expanded subsequently and

replaced steel covered trenches completely in the 1920s.

Figure 1 - Construction of a masonry tunnelSaint Martin Nadaud, 1904.

Figure 2 - Construction of a steel cover(Palais Royal station, Line 1 – 1998).

• Arch segment linings

Linings using prefabricated sections have been widely used from the 1960s

onwards, either to build circular tunnels or to build large deep-level stations

using the Jacobson method.

2 - Evaluating the condition of the assets

Data monitoring and management

Monitoring of bridges and tunnels on the RATP infrastructure in use [rail net-

works and dedicated corridors] draws extensively on the Technical Instruction

for the Monitoring and Upkeep of Bridges and Tunnels (Instruction Technique

pour la Surveillance et l’Entretien des Ouvrages d’Art, ITSEOA). However, it

takes into account specific considerations for rail operations.

RATP underground structures are subjected to several levels of monitoring and

inspection. These are as follows:

• Continuous monitoring on a daily basis by all personnel.

• Scheduled regulatory monitoring, comprising detailed inspections every five

years and intermediate periodic inspections depending on the condition of

the structure. This monitoring is entrusted to Bridge and Tunnel Inspectors

Figure 3 - Reinforced concrete structurefor the crossover of lines 8 and 9.

Figure 4 - Arch segment lining on RER line Abetween Etoile and La Défense.



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(visiteurs-inspecteurs d’Ouvrages d’Art). It is carried out at night for rail tun-

nels and during the day for access structures.

• Specific heightened monitoring is put in place for structures for which spe-

cific risks have been identified (in particular, sensitive surrounding terrain).

2.1 - Standard monitoring of structures

The first two levels correspond to traditional structural monitoring and entail

requests for works in the form of specific sheets. Depending on their urgency

and scope, these are either carried out as part of standard upkeep or as part

of specialised maintenance or scheduled repair works.

Depending on how technical they are, visits are carried out by technicians,

senior technicians or engineers. During inspections, a scanner is used to carry

out tunnel measurements using both visible and infrared light.

All data gathered during these visits is summarised on “health” sheets for the

structure and fed into a database on an intranet. This facilitates consultation

and archiving of information. Known as Maintenance Assistée du Réseau, Ins-

pection des Ouvrages et Notation or MARION for short (Assisted Network Main-

tenance, Inspection and Ranking of Structures), this allows both aboveground

and underground rail assets operated by RATP to be managed.

The database also includes topometric data and can be interrogated using

queries. It also serves as a reporting tool, monitoring the progress of visits and

inspections as well as changes in the ranking of structures.

2.2 -Specific heightened monitoring

Some structures are the subject of specific heightened monitoring. Some

examples of this follow, to illustrate how risks relating to the surrounding terrain

are taken into account.

• Risk from unstable quarry workings

Much of the network has been built above former quarry workings, mostly

limestone. Major consolidation works have been carried out in such cases.

To monitor the condition of this consolidation, visits are scheduled annually

and carried out jointly with the Quarry Inspectorate (Inspection Générale des

Carrières).

• Risk from cavities forming beneath structures

The northern part of Paris is at risk from gypsum dissolution subsidence (as

defined in the inter-prefecture order dated February 25, 1977). To protect itself

against this risk, RATP has carried out a number of actions on this part of the

network:

• Topographic levelling to detect soil movements that could be advance signs

of cavity formation.

• Deep destructive boreholes 30 metres beneath structures, with logging of

the borehole parameters to detect cavities or decompressed areas of soil.

• Risks from cavities forming behind side walls.

Core samples though masonry to the soil are carried out to assess the cha-

racteristics of the masonry and the quality of its contact with the soil. Injection

tests are also carried out.

3 - Risk analysis and the maintenance master plan

RATP has put in place a maintenance master plan for civil engineering

structures, based on risk analysis. The purpose of this master plan is to define

the asset management strategy to be conducted on rail infrastructures.

Figure 6 - Tunnel cross-section showing deep destructive boreholes in green.

Figure 7 - Core sample in a side wall to survey the condition ofmasonry and the quality of its contact with the soil.


Figure 5 - Plan of quarry workings around Denfert Rochereau, showingthe consolidation works beneath various lines (metro and RER).


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This is based on the inventory of risks relating to the following:

• ageing of structures;

• their environment.

It is detailed for each network and the various structural pathologies.

The method for analysing and prioritising structures and actions is organised

as follows:

• identification of environmental risks;

• identification of risks relating to the condition of structures;

• identification of risks relating to changes in operating conditions and/or legis-

lation.

Causes and consequences for the structures, their environment and their ope-

ration are evaluated for each risk.

Risk criticality is analysed, distinguishing the following aspects:

• occurrence;

• seriousness with regard to the safety of users, availability, economic consi-

derations and comfort.

Previous maintenance operations are also taken into consideration to define

a future risk reduction strategy. Lastly, taking into account the impact on other

projects, a maintenance scenario with a twelve-year financial projection is

drafted.

In conclusion, the Maintenance Master Plan comprises:

• capitalisation and summary of knowledge of structures, their condition and

their pathologies;

• a twelve-year maintenance policy.

4 - Maintenance strategy and activity

The maintenance strategy is defined in the maintenance master plan described

above.

The annual repair and maintenance programme is based on a combination of

the following:

• the Maintenance Master Plan, which establishes the basic structure of the

programme,

• the results of monitoring, which give rise to proposals for major maintenance

• operating constraints and opportunities (for rail and also highways, particu-

larly for surface waterproofing works).

Taking into account these constraints and opportunities requires a great deal

of anticipation, which in turn involves being aware of what is happening within

the company and outside it, and a certain degree of flexibility in scheduling

operations (for instance by swapping them around).

The main types of infrastructure maintenance works are as follows:

• For masonry structures, upgrading masonry and soil adhesion by injectingcement grouting This operation makes it possible to fill cavities present in masonry or between

the masonry and the soil (due in particular to the shield timber rotting away

over time). Making the lining of one piece and ensuring that it fits flush with

the soil helps ensure the stability of the structure over the long term.

• Repairing surface waterproofing for steel and reinforced concrete covers

Repairing waterproofing is a vital operation to ensure the longevity of structures

at shallow depth, of which there are a great many on the network.

• Treating reinforced concrete structures that have been damaged, in particular by carbonation

Figure 9 - Repairing waterproofing beneath a road, Paris.

Figure 10 - Repair of reinforced concrete beams dating from the 1920sand damaged by corrosion following carbonation.


Figure 8 - Injectingcement grouting into masonry at Malesherbesstation.


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Appendix 4Hydroelectric dam galleries

1 - Assets

Power and discharge tunnels account for a total of 1520 km, with an average

cross-sectional area of 10 m2. Surge chambers and shafts account for 9 km

total length, with an average cross-sectional area of 38 m2.

The average age of these structures was 61 years in 2010.

In qualitative terms, the design of these underground works is extremely

influenced by the period when they were built and the local topography. The

route of the oldest power tunnels tends to follow the side of a valley and follow

the river (with little horizontal or vertical overburden); the techniques of

that time required a large number of access windows. Once surveying was no

longer required due to progress in underground topography and better drilling

and mucking equipment, more recent structures (i.e. since 1960) have longer

sections without windows and with overburdens of up to several hundred

metres.

2 - Comparative ranking of structures in terms of criticality

Risk analysis

Risk analysis is based on functional analysis of structures and their failure

modes. Each failure mode is qualified in terms of consequences and

occurrence; the latter incorporates stable intrinsic causes (level of design,

quality of construction, etc.) and variable causes (deterioration, excess

stress,etc.)

For each failure mode, the consequences are evaluated by the local operator

in terms of the impact they are liable to have on three major aspects of

hydraulic assets: safety, performance and adherence to regulations.

Number of structures

Power tunnel 518

Discharge gallery 78

Shaft 55

Water intake tunnel 246

Surge chamber 182

Expansion chamber 79

Pressure chamber 96

Consequences are estimated for each aspect on a scale of seriousness

of 0 to 3 in order to rate the impact of failure mode.

IS, IP, IR evaluated on a scale of 0 - 3

Occurence

Occurrence is determined for each failure mode on the basis of combinatory

rules for criteria relating to the causes of these failures. Four levels of occur-

rence are established:

The combination of the two parameters makes it possible to determine urgency

for each aspect and thus the criticality of each item. Risk analysis makes it

possible to draw up a map of the assets, which in turn helps with the definition

of maintenance programmes.

It should be noted that the method has been extended to all types of equipment

in the Hydraulic Engineering Production Division, each with its own criteria and

influence factors when it comes to determining the occurrence of failure

modes.

Failure causes are grouped into two categories:

• the first includes causes that are relatively stable over time, making it possible

to estimate the “sensitivity of the structure to failure”. This consists of the

design characteristics, the external environment and the mode of operation

• the second comprises causes liable to change over time, making it possible

to estimate the “degree of deterioration” of strength. This consists of all

forms of damage and their progression.

Occurrence is determined by combining sensitivity and the degree of deterio-

ration.

3 - Determining urgency with regard to each aspect

Rule tables – which may differ for each aspect – make it possible to determine

the urgency for each of the latter.


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4 - Criticality

The combination of degrees of urgency, always in the form of logical rules,

makes it possible to determine criticality.

5 - Conclusion

Prioritisation of structures in terms of criticality, determined for each according

to common rules that ensure consistency, makes it possible to draw up the

list of critical structures on which the maintenance programme will be based,

including the list of detailed diagnostics to be performed.

Common rules are developed on the basis of a generic risk analysis depending

on the type of structure under consideration.

In turn, diagnostics make it possible to develop the countermeasures to be

implemented; these may take the form of operational restrictions or

short/medium term maintenance.


1 - Asset inventory

The Ile-de-France Public Drainage Authority (SIAAP) has a network of main

sewers extending throughout its territory, with a total length of 430 km.

The underground structures of which this consists have diameters of between

2.00 m and 6.80 m. They are not accessible when in service. They are fitted

with manholes spaced between approximately 100 m and 1000 m apart.

The location of 95% of these structures is known to within category A accuracy

as defined in the new DT-DICT regulations. They have all been mapped using

a GIS.

GIS map of SIAAP main sewers.

2 - Asset inventory

• Intrinsic characteristics: Date of construction: average age is relatively high,

70% of assets are over 30 years old.

Histogram of construction dates.

• Mode of construction: underground using the conventional method for the

oldest sewers, using TBMs for the most recent ones.

• Nature of materials: millstone grit blocks or coated limestone, concrete

poured on site, prefabricated arch segments.

• Dimensions: mostly circular with diameters of between 2.00 and 6.80 m.

Appendix 5SIAAP network of main sewers

0%

More than 60 years

30-60 years

20-30 years

10-20 years

Less than 10 years

5% 10% 15% 20% 25% 30% 35% 40% 45%


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• Geological and hydrogeological environ-

ment: sedimentary formations, alluvial soil,

sand, limestone or marl; submerged, depen-

ding on their elevation, by fluvial aquifers and

by perched aquifers.

• History (incidents, works, etc.): no serious

incidents; recurring corrosion damage due to

sulphates, decompressed surrounding terrain

or loss of watertightness.

• Adjacent surface and underground struc-

tures: a large number of structures adjacent

to the networks, located in an extremely

dense urban environment.

3 - Risk assessment and assetmanagement

A software solution known as GUEPARDS has been developed, allowing the

following:

• Establishment of a database descri-

bing the structures,

• Evaluation of the criticality of struc-

tures and ranking them,

• Taking into account present and past

interventions on the structures,

• Assistance in scheduling forthcoming

interventions: inspection, diagnostics,

works.

The method used to develop this tool is

as follows:

• Use of the Geographic Information

System supplemented by documen-

tary research to identify, locate and

qualify structures in asset segments

with a length of 100 m.

• Assignment of a score for each asset

segment in line with the RERAU 1

method:

- Environment score, calculated on the basis of the structure’s initial

characteristics and environmental data.

- Structure score, taking into account pathologies observed during visits

and detailed inspections.

- Network score, based on the criticality of the structure in the hydraulic

master plan.

Together, these scores make up an overall score which reveals structures in

environments that are sensitive or that have been identified as risk-prone and/or

seriously damaged structures and/or structures that are network-critical.

The flowchart below outlines the various functionalities of this process.


The results are illustrated below, in the form of summaries, lists of structures

to be treated, and thematic maps.


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1 - Assets

The drainage network of the Seine Saint-Denis département comprises the

following:

• 700 km of structures, including 500 km of accessible collectors

• 200 km of pipes

• and 36,000 branches.

Most of the structures date from the early 20th century, the oldest from 1821

(or perhaps even earlier in the royal town of Saint-Denis).

A study programme to investigate the pathology of drainage structures known

as “D.A.R” (“Démarche globale de l’Auscultation à la Réhabilitation”, Policy

from Inspection to Renovation) was set up in 1985. This policy was designed

for day-to-day management and preventive care of the drainage network,

which represents a significant asset. Four years’ worth of development was

required before it became operational in 1990. It is structured around three

core aspects: familiarity with the assets in the “Study” aspect, structural reno-

vation of the most damaged structures following studies, in the “Works”

aspect, and lastly “Capitalisation” of the findings using data processing and

reconstituting the department’s memory to make the most of the knowhow

and experience built up over the subsequent 25-year period.

One of the distinctive features of this programme is the cross-checking of data

for each structure BEFORE, DURING and AFTER works, helping to improve our

experience when it comes to choosing techniques and making appropriate

judgements in terms of the asset management of our structures.

2 - “A.U.D.A.C.E” Drainage Master Plan

To date, this study programme has been operational since 1990 and fulfils the

commitments of the DEA’s master plan, known as “AUDACE”. This ensures

that the master plan is followed and results monitored as regards familiarity

with the assets and renovation works.

3 - Methods

The DAR study programme determines the condition of structures before

works in terms of four levels (monitoring, preventive, curative and protective

measures – collapse) using notions of safety and structural longevity. It is then

applied during worksites with quality monitoring during (or at the end of)

works during structural repairs, and is then cross-checked after works to

measure the new condition by checking the effectiveness of the latter. This

value is compared with the results measured prior to works. This makes it

possible firstly to understand and measure the impact of works, and secondly

to improve our appraisal in terms of cross-checking of data. In addition, for

sensitive structures that are still under stress or that have undergone major

renovation, monitoring of the renovated collector is organised with local teams,

firstly to check the behaviour of the structure over time and secondly to inter-

vene immediately in the event of any incident or defect. If it includes instru-

mentation with equipment, this part of monitoring is referred to as the “Civil

Engineering Maintenance Dossier”, (“Dossier de Maintenance de Génie Civil”,

DMGC).

Lastly, the Research and Development (R&D) aspect to improve familiarity with

works tools and techniques is present in the study programme, as are studies

on the collapse of a drainage structure and on the durability of techniques and

their effectiveness after 20 years, in the light of the economic impact of this

type of activity.


Appendix 6Drainage network managed by the Seine Saint-Denis Conseil général

Crown damage.

Testing fresh concretefor a reinforced shellmade of sprayedconcrete.

DMGC - Set of sewermonitoring pegs.

Structural damage.


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All of this data, information and results, acquired throughout all these phases,

is processed with powerful computer tools using very precise organisation and

terminology, defined in the DAR programme ever since its implementation and

fixed over time. Treating data in exactly the same way over a 25-year period

ensures the quality of the information and above all the certainty of speaking

the same language over time in order to explain types of damage and the

appropriate treatment. The main computer tools used are as follows:

• GIS (3rd-generation, 2011). This comprises some 100 layers including 4

major layers for asset management (condition of structures, maps of geo-

logical and hydrogeological risks and monitoring of groundwater)

• SODAR (DAR Operations Monitoring, Suivi des Opérations du programme

DAR); this interacts with the GIS, making it possible to manage all our study

work before, during and after works over time, for works on over 400 col-

lectors

• GEOLOG lists all our survey work, boreholes and other tests ever since the

outset of the programme, interfacing with the GIS

• AVICA (Old Map Viewing Application, Applicatif de Visualisation des Cartes

Anciennes); this makes it possible to “understand the future of structures

by looking at their past over a period of three centuries”, using three major

families of map: historic maps, business-specific maps and military maps;

to date, this comprises some thirty maps combined with the outline of the

drainage network and inspection chambers.

this stage (for instance, GEOLOG for surveys, AVICA for the history and

SODAR/SIG for information about the asset).

Following this analysis, the programme defines the structures that are to be

subject to a visual inspection/diagnostic over the following year, depending on

the risks and urgency of the request. Following these studies, the condition of

the asset is defined in terms of four levels, with action to be undertaken within

the following periods:

• Monitoring - normal condition (with or without maintenance works) <10

years: fulfils safety and longevity conditions

• Preventive - degraded condition (with renovation works) < 7 years: meets

safety conditions

• Curative - highly damaged condition (with renovation works) < 3 years, no

longer fulfils safety and longevity considerations

• Protective measures - danger of collapse (with urgent works) within the

year

This ranking incorporates all the scores and risk values that have been pro-

cessed previously, and defines the overall condition of the asset, with priori-

tisation and various types of work and related costs.

This data then makes it possible to develop our annual works programmes

each year, or even on a 3-5 year basis, as governed by the AUDACE master

plan.

4 - Conclusion

The entire drainage network is visited by sector teams over a three-year period;

an average of 15 km is inspected visually/diagnosed every year, the main

constraint being financial. 5 km of works are carried out on accessible struc-

tures (collectors) every year, 2.5 km per year on non-accessible structures

(pipes), which corresponds to a 100-year work schedule. To date, we no longer

need to deploy protective measures on our network.

The application of this programme generally requires one to three years in the

STUDY phase in order to establish the condition of a structure presenting

defects, and the same duration or more in the WORKS phase for it to be repai-

red, depending on the urgency and available resources.

All of these actions help contribute to improve the drainage assets and above

all, confirm the overall asset management policy that has been implemented

in Seine Saint-Denis for over two decades now. t


The AVICA application and the benefits it brings to our day-to-day work can be summarised in a simple sentence:

“To understand the future, it is necessary to look at one’s past”.This enables the collective memory of the department to be reconstituted

through the ages and help attempt to explain some of the phenomena observed in the present day.

1887 map of the outskirts of Paris overlaid on the contemporary Michelin map.

The method used starts by analysing report forms passed on by any individual

who notices a problem and comparing this with prior information that describes

adverse factors for a given structure (year and mode of construction, type of

materials, dimensions, impact on the network, history, geotechnical and

hydraulic information, etc.). Other factors are also considered, such as consul-

tation of all the databases at our disposal that could help form a judgement at


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