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SINGAPORE INSTITUTE OF ARCHITECTS (SIA) Design-for-Safety (DfS) Handbook

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01. In this pocket guide we seek to provide a simple, step-by-step approach to Design-for-

Safety (DfS) in accordance with the DfS principles presented in the WSH Council’s

‘Guidelines to Design for Safety in Buildings & Structures’.

A project’s DfS exercise should aim at invoking a systematic and disciplined approach to

giving attention to risks borne out of the design of a building. DfS draws upon the

professional pride and moral duty of designers to be responsible in the designs they

prepare. In seeking to optimise the effectiveness of the DfS process, it is intended to be

applied as an integral and natural part of the normal design process. The DfS process

should be aimed at promoting effective and creative outcomes which are meaningful

and to-the-point. The DfS process should avoid overly contrived, tedious and onerous

procedures which are counter-productive. The DfS process is not intended to create

paperwork for its own sake, nor to breed resentment by becoming a demoralising

burden of formality. The DfS process should encourage willing involvement and creative

contributions by designers.

02. The key objectives of DfS are :

1. the avoidance or mitigation of risks arising from the design of the building, and

2. the awareness of affected persons of

(i) significant risks arising from the building development that they will need to

face and address, and

(ii) safety measures provided in the building development that they can make

use of to address the safety risks they face.

Affected persons are those who are affected by the building (including those persons

who construct, alter, demolish, occupy, or maintain the building, or persons who visit or

are proximate to the building).

Different sets of affected persons exist at the different stages of a building

development’s life (ie construction, use/occupancy/maintenance/alteration, and

decommissioning and demolition), and each stage should be considered for DfS

purposes.

03. We approach DfS in regard to two principal ‘design’ exercises:

1. Selection of Site.

2. Design of the building development.

04. For selection of Site, the safety-feasibility of a proposed Site should be determined.

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The safety-feasibility should comprise the acceptability of the proposed Site relative to

tolerances for safety risks.

The safety feasibility should consider:

(a) The safety-risk-impact of the proposed type and scale of building development

on the surrounding context.

(b) The safety-risk-impact of the surrounding context on the proposed type and

scale of building development.

(c) The safety-risk-impact of the existing Site conditions and dimensions on the

proposed type and scale of building development.

05. For design of the building development:

(1) the significant risks of a proposed design for the building development should be

determined, and

(2) opportunities to design-in safety measures should be identified and taken..

The affected persons need to be made aware of significant risks and the safety measures

relevant to them.

The significant risks are those which:

#1. Are not a commonly encountered and understood risks, and require special

methodology to address the risks, and

#2. Are not obvious to the risk-facer, and

#3. Are of a significant severity level (eg debilitating or fatal injury or illness).

06. In identifying significant risks, the designer(s) should seek to describe the risk/hazard in

terms of:

> Affected Person

> Activity / Task -- eg specific type of construction or maintenance work

> Risk Source -- eg working at height

> Conditions of Risk Exposure – eg difficulty of access to work

> Kind of Accident / Harm – eg injury or death from falling

07. The building’s significant risks and the opportunities for safety measures are identified

through DESIGN REVIEW by the building’s designers.

Design Review involves:

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(A) looking at the proposed building design,

(B) at different stages of design development,

(C) from different perspectives,

in order to ‘brainstorm’ for significant risks and opportunities for safety measures.

Identified significant risks should be assessed, and the risk omitted or risk level reduced

where possible.

08. Design Review should be conducted at the various stages of design development (before

and during construction), such as:

(i) Concept Design

(ii) Schematic Design

(iii) Development Control (DC) Plans

(iv) Developed Design

(v) Building Plans (BP)

(vi) Working Drawings and Specifications and Preliminaries (for tender/pricing

and construction)

(vii) Shop Drawings and Method Statements [by contractors –ie throughout the

construction stage]

Design Review should be carried out on:

(a) designs for the Permanent Works

(b) designs for temporary facilities (eg show flats)

(c) designs for Temporary Works and work approach/methodology

(d) design revisions to (a)-(c).

Design Review should include for:

(i) designs by the Architect.

(ii) related designs by other consultant designers

(iii) related designs by specialist contractors

(iv) related designs by general/trade contractors

09. Note that the Architect is part of a team of designers who should consider various

modes of design in a coordinated manner, including:

(i) Site selection.

(ii) Design of the permanent works (building development, including Site

planning).

- by principal designers (including architects, engineers and other

consultants)

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- by specialist design-&-install contractors

(iii) Design (including selection or prescription) of temporary works.


consultants)

- by contractors

(iv) Design (including selection or prescription) of the approach and

methodology of work.


consultants)

- by contractors

10. Design Review should involve examination of all modes of design information that

represents the design, including:

(a) BIM models / architectural drawings,

(b) Schedules / tables of data

(c) Specifications, annotations and legends

(d) Preliminaries, site management specifications, etc.

(e) Physical models, artists impressions and 3D images.

(f) Mock-ups, prototypes and materials samples.

(g) Product literature / brochures

11. ‘Brainstorming’ should be carried out with the permutations of the following

considerations in the back of the designer’s mind …

(A) Design Review should involve examination of the design information from

different perspectives, such as:

(a) Building elements

(b) Building materials

(c) Layouts, configurations, dimensions and proportions

(d) Scale (Site, Building, Rooms/Spaces, Elements, Components)

(e) Work approaches & methods.

(B) Design Review should consider the various different modes of hazard /

accidents, such as those outlined in Appendix 1.

12. The modes of hazard / accidents, such as those outlined in Appendix 1 can be seen as

having the following underlying factors:

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'RISK SOURCE:

> Access

> Ergonomics / Restricted Space

> Material / substance

> Objects

> Tools & Method

> Environmental

CONDITIONS OF RISK EXPOSURE:

for example ...

> Working at height

> Restricted working space

> Concealed working space

> Flame / Heat

> Thermal comfort

> Light levels

> Air quality

> Pollutants

13. Some typical ‘activities’ (ie modes of work) under which affected persons might be

exposed to risk includes, but is not limited to:

Construction (& A&A):

-Transport / Delivery

- Offload at Site

- Storage on Site

- Positioning / Lifting

- Related Temporary Works

- Installation

- Testing & Commissioning

- Cleaning

Maintenance:

- Servicing & Repairs & Cleaning

- Replacement / Reapply / Renewal

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14. Any significant risks that were not avoided in the initial designing should be identified

and assessed, and the risk eliminated or reduced where possible (to achieve an

acceptable level of residual risk, within established tolerances):.

First priority is to change the relevant aspect of the design to ‘eliminate’ the significant

risk.

Second priority is to change the relevant aspect of the design to ‘reduce’ the significant

risk, in order of preference:

1. by ‘substitution’ with a different design,

2. with an ‘engineered’ design solution (passive),

3. with an ‘engineered’ design solution (active) – eg built-in provisions for

application of task-specific tools/equipment and processes,

4. by mitigating the risk level with application of ‘administrative controls’ or

5. by mitigating the risk level with application of ‘personal protective equipment

(PPE)’.

This process should consider risk v. benefits v. practicable alternatives.

This process gives a conscious, deliberate, systematic and disciplined approach to DfS.

15. The affected persons need to be made aware of significant risks and the safety measures

relevant to them.

This is most effectively done by adding safety ‘advisory notes’ to the design information

that the affected persons will refer to. For example:

(1) ‘Advisory notes’ for construction workers is best integrated in the working

drawings, shop drawings, specifications, method statements, etc to which they

are referring in the course of their works.

(2) ‘Advisory notes’ for maintenance personnel is best integrated in the as-built

drawings and/or operating procedure statements/instructions in operation &

maintenance manuals.

The ‘advisory notes’ specifically seek to make affected persons aware of the significant

risks they must address and the safety measures available to them in the course of their

activities.

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‘Advisory notes’ should:

(A) Be placed as mark-ups on the actual design information so it is prominently

highlighted and readily apparent to the affected person in the course of their

activity (it should not be put in a separate document that is non-specific and

detached, as these are usually put away on a shelf and collect dust).

(B) Be clear and succinct, and preferably of a graphic mode (eg pictograms) which

are effective for their ease of reading and understanding.

16. As a supplement to the ‘advisory notes’, the designer should also consider conducting

briefing sessions for affected persons to verify that they have realised and understand

the risks that are highlighted in the ‘advisory notes’.

Such briefing sessions are best conducted at the time of passing-on the design

information (and ‘advisory notes’) to the affected person.

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APPENDIX 1:

- Modes of Hazards / Accidents

The designers should keep the following modes of hazards / accident in mind when ‘brainstorming’

to identify risks:

According to MOM statistics, the most-occurring accidents in relation to construction works are

1. Falling from height

2. Struck by objects (moving objects)

3. Struck by objects (falling objects)

4. Caught in-between Objects

5. Collapse / Toppling Equipment

(both Temporary and Permanent equipment)

6. Collapse / Toppling of Structure

(load resisting elements, including Soil/Rock -- both Temporary and Permanent structures)

7. Slips, Trips and Falls

A wide scheme of hazards / accidents would consider:

RISK AGAINST SAFETY (INCL. HEALTH & WELL-BEING), relative to 'design objective' and 'design

approach / solution' :

ACCESS

- Falling from height

- Trapped or Confined Space (enclosed with limited access and/or egress / emergency exit)

OBJECTS

- Struck by objects (moving objects)

- Struck by objects (falling objects)

- Caught in-between Objects

- Cut / stabbed by Objects

- Strike against Objects

- Stepping on Objects

- Lifting or Manoeuvring Injury

TOOLS / EQUIPMENT & METHOD / PROCESS - Collapse / Toppling Equipment (both Temporary and Permanent equipment) - Mechanical Injury - Ergonomic / Strain Injury - Tool Breakage / Failure - Tool 'give-offs' (dust, grit, splinters, fumes, noise, sparks, flame, heat, vibration, etc) - Electrocution - Heat / Thermal Injury

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PHYSICAL CONTEXT - Collapse / Toppling of Structure (load resisting elements, including Soil/Rock) (both Temporary and Permanent structures) - Slips, Trips and Falls - Glare / Reflection ERGONOMICS - Over exertion / strenuous movement - Restricted / Awkward Movement Space - Lighting - Ventilation / Air Quality

HAZARDOUS MATERIALS / SUBSTANCES [incl in solid, liquid or gas, and as smoke, dust, mist, fumes (gas / vapour)] Exposure to Harmful Substances - Toxic / Poisonous - Asphyxiating - Allergenic - Explosive - Flammable - Corrosive - Oxidising - Radioactive Exposure to Biological Materials - Infectious / Biological Hazard (Pathogen) OPERATION / ACTIVITY - Electrocution - Exposure to extreme temperatures - Fire - Explosion - Drowning - Mechanical / Impact Injury ENVIRONMENTAL CONTEXT - Sanitation/hygiene - Pests / Infestations - Thermal Comfort - Noise Pollution - Smells / Odors - Sun / Glare - Rain - Wind - Lightning - Psychological Disturbance

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ACTIVITY CONTEXT - Traffic Accident - Anti-social behaviour EMERGENCY SITUATION (Response & Preparedness: Escape / Refuge, Containment, Fighting / Arresting, etc) - Fire - Natural Disaster (Earthquake, Precipitation / Flood, Wind) - Violence / Disorderly Conduct - Biological, Chemical or Radiological Threat - Explosion / Bomb Threat - Vehicle Crash - Disease Outbreak - Health / Hygiene Threat

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APPENDIX 2

- Design Review topics

In conducting Design Review to identify risks, the designers can consider the following topics (as

arrange here under the GUIDE 1, 2 & 3 classification of design review provided in the WSHC DfS

Guidelines):

> GUIDE 1 - Site Selection Site Feasibility Analysis - Impact on Site / Development by existing surroundings - Impact on Site / Development by environmental factors - Impact of Site / Development on surroundings/public - Existing Site Conditions - Conceptual/Schematic Site Planning - Constraints & Opportunities - Feasibility of Construction Operations & Site Management - Adjacent Structures - Ground / Soil Conditions > GUIDE 2 - Site Design Schematic / DC - Impact on Site / Development by existing surroundings - Impact on Site / Development by environmental factors - Impact of Site / Development on surroundings/public - Existing Site Conditions - Conceptual/Schematic Site Planning - Constraints & Opportunities - Feasibility of Construction Operations & Site Management Developed / BP - Adjacent Structures - Ground / Soil Conditions

> GUIDE 2 - Detailed Design & GUIDE 3 - (i) Specialist Contractor Designs Schematic / DC Planning - Design of Permanent Works - Layouts / Configurations & Spatial use/function

Developed / BP - Design of Permanent Works & Temp Facilities - Site Formation - Design of Permanent Works & Temp Facilities - Underground Services - Design of Permanent Works & Temp Facilities - Sub-Structure - Design of Permanent Works & Temp Facilities - Building Super-Structure & External Works Structures - Design of Permanent Works & Temp Facilities - Building Envelope - Design of Permanent Works & Temp Facilities - Internal & External Assemblies, Systems & Plant (Arch + M&E)

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Developed / BP &/or Construction Contract Documentation - Design of Permanent Works & Temp Facilities - Materials, Fixtures & Detailing (Arch + M&E) - Design of Permanent Works - General Design Function Specialist Contractor: D&B Documentation Specialist Contractor: Shop Dwgs, Materials Selections & Method Statements > GUIDE 3 - (ii) Design of Temporary Works [for Construction] Types of Temporary Works & Approach to Methodology : Employer/ Consultant Design - Prescription/specification of Site Arrangements, Facilities and Scheduling requirements - Interim Works for Site Arrangements & Facilities Types of Temporary Works & Approach to Methodology : Contractor's Design - Interim Works for Site Arrangements & Facilities - Interim Works for construction of Permanent Works

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APPENDIX 3

- PROJECT LIFE STAGE / STAKEHOLDER ACTIVITY MODE

> Site Selection (Analysis of feasibility for the proposed development with respect to Safety & Health) (Stakeholders: Generally, as per the following project stages). > Before-Construction (Site Upkeep and Investigations / Surveys) (Stakeholders: Owner, Developer, Consultants, Surveyors and Investigators, Preliminary Works Contractors, General Public) > Construction (Stakeholders: Contractors, Employer & Consultants, Site Supervision Staff, Visitors & Inspectors, General Public) (Note: Excludes off-site manufacture, prefabrication and assessmbly, etc)

... MOBILISATION / SITE SET-UP

... DEMOLITION

... SITE CLEARANCE

... EARTHWORKS

... EXCAVATION

... SUB-STRUCTURE

... SUPER-STRUCTURE & EXTERNAL WORKS

... BUILDING ENVELOPE

... ASSEMBLIES, SYSTEMS & PLANT (ARCHI & MEP)

... FINISHES & FIXTURES

... DEFECTS RECTIFICATION > Occupancy - Use (Stakeholders: Occupants & Visitors & Inspectors, Service Providers, General Public) > Occupancy - Maintenance (Stakeholders: Property Managers & Maintenance Contractors, General Public)

> Additions & Alterations (Stakeholders: as above, for Construction + Use) > Decommissioning and Demolition (Stakeholders: as for Construction)

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