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DRAFT
SINGAPORE INSTITUTE OF ARCHITECTS (SIA) Design-for-Safety (DfS) Handbook
Page 1 of 13
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.
- by principal designers (including architects, engineers and other
consultants)
- by contractors
(iv) Design (including selection or prescription) of the approach and
methodology of work.
- by principal designers (including architects, engineers and other
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)