Andrew Rattray - HSE Construction Engineering Specialist

Health and Safety Executive

Stafford & Shropshire WWT Temporary Works Seminar Stoke-on-Trent, 11th September 2013 Andrew Rattray, HSE HM Specialist Inspector (Construction Engineering)

Temporary Works

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Historical perspective Bragg Report and BS5975 Why HSE interested? What the law says What the guidance says Common problems

Temporary Works - Historical perspective - 100 years ago.

Britain’s worst construction accident in terms of fatalities.


Before the accident, a fully timbered deep excavation.


The report by W.W Squire, dated 30th August 1909, gives a total of 38 fatalities.



(source E Little – The building of the Barton High Level Bridge)


Collapse of a scaffold falsework support tower – Barton Bridge, Manchester 19th February 1959. 4 workers fatally injured.

Temporary Works –

Historical perspective – 50 years ago

Evidence given at the Inquest: • Scaffolding not installed in accordance with the design drawings • The design drawing was not a working drawing and only gave an indication of the structure • Worn and corroded scaffold tubes had been used • Lack of lateral bracing • Design carried out by an “estimator/ draughtsman” – not “passed” by an engineer • Bulging of the scaffold noted but not acted upon (source E Little – The building of the Barton High Level Bridge)


2nd accident - overturning of bridge beams – Barton Bridge, Manchester 31st December 1959. 2 workers received fatal injuries.

Temporary works - Bragg

March 1971 – Birling Road overbridge, Kent 1 killed and 5 seriously injured

Temporary works - Bragg Report by a committee under the Chair of SL Bragg FIMechE, FRAeS, Vice-Chancellor and Principal of Brunel University. Appointed by the Secretary of State for Employment and the Secretary of State for Environment in March 1973. Interim Report published April 1974. Final Report dated June 1975. Published 1976.

Temporary Works - Bragg Recommendations essentially made under the categories of:a) technical (Chapter 4) b) procedural (Chapter 5) c) training / competence (Chapter 6)

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The role of the ‘Temporary Works Co-ordinator (TWC), recommended in the interim report, is described in Chapter 5 of the report.

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Similarly the importance of adequate design briefs, co-ordinating and checking designs is dealt with (Chapter 5).

Temporary Works - Bragg •

Recommendations (continued): Technical recommendations included those dealing with:– horizontal loads, – lateral stability, – 3% horizontal load rule, – lacing and bracing, – discontinuity in falsework beams, – jack extensions, – grillages, and – proprietary equipment.

Temporary Works - Bragg Recommendations (continued): Temporary Works Co-ordinator for major falsework structures (e.g.. bridges) recommended (insisted) that TWC should be a Chartered Engineer. Considered that for smaller jobs TWC need not be C.Eng. but must have experience of falsework, Considered that smaller contractors could appoint a TWC from outside,

Temporary Works – BS 5975 1982 – BS 5975 first published. Reflected recommendations of Bragg. Dealt only with falsework – “Code of practice for falsework” 1996 - 2nd edition of BS 5975, some technical changes, still just falsework 2008 – 3rd edition of BS 5975, major update, still covers design of falsework BUT procedures now applicable to ALL temporary works – “Code of practice for temporary works procedures and the permissable stress design of falsework” 2011 - amendment A1, updated wind to Eurocodes, amplified some of the wording relating to procedures

Temporary works – BS 5975

BS 5975:2008+A1:2011 Over 200 pages long 14 pages on temporary works procedure Rest on the permissible stress design of falsework

Temporary Works – BS 5975 So what are temporary works? BS5975:2008 defines them as: Parts of the works that allow or enable construction of, protect, support or provide access to, the permanent works and which might or might not remain in place at the completion of the works ..an “engineered solution” used to support or protect either an existing structure or the permanent works during construction, or to support an item of plant or equipment, or the vertical sides or slopes of an excavation during construction operations on site or to provide access

Temporary Works – Why HSE interested

So why are the HSE taking such an interest?

This wasn’t…..

Or this

Or this

Live railway. Workers on a break

And so on…………

Gravity always wins

Temporary Works - Why HSE interested

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Inadequate or poor TW is implicated in many incidents – Trench collapses – Scaffold collapses – Basement /underpinning collapses – Structural collapse Reflects – Poor clients – Incompetent contractors – Often overlooked by CDM Coordinators

Temporary Works – Why HSE interested What is HSE doing? Encouraging industry to control the risk by

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Increasing awareness of the importance of managing temporary works effectively – Supporting events like today

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Checking on contractors’ management arrangements for temporary works

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Checking on the competence of those doing temporary works management & design

Temporary Works – What the law says So what does the law require?

Temporary Works – What the law says The small print CDM Regulations 2007 and the ACOP specifically mention temporary works:

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“Structure” means… “any formwork, falsework, scaffold…” (Reg 2(1))

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“Designers therefore include: ... temporary works engineers…” (para 116)

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“Construction phase plan… Arrangements for controlling significant risks… (iv) stability of structures… including temporary structures… (ix) work on excavations…” (Appendix 3)

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“The design of temporary works… falls within the scope of CDM2007. CDMC’s have to take reasonable steps to ensure co-operation between permanent and temporary works designers…” (para 104)

Temporary Works – What the law says CDM2007 Regulation 4 (competence): competence required of all those with a role to discharge in the planning, design and execution of temporary works. Regulations 5&6 (cooperation and coordination): cooperation and coordination of activities including temporary works, incumbent on all involved. Regulation 10 – (client’s duty to provide information): provision by client of preconstruction information (e.g. ground conditions, structural drawings). Regulation 11 (duties of designers): avoidance of foreseeable risk arising from preparing or modifying designs. Regulation 13 (duties of contractors): planning, management and monitoring of construction work. Regulation 18 (additional duties of designers): provision of information to assist the CDM coordinator CDM(C).

Temporary Works – What the law says Regulation 20 (duties of CDM(C)s): all reasonable steps to ensure designers comply with their duties and to ensure cooperation between designers and principal contractors in relation to any design or design change. Regulation 22 (duties of the principal contractor): planning, managing and monitoring the construction phase. Regulation 28 (stability of structures): any support or temporary structure must be designed, installed and maintained so as to withstand foreseeable loads. Regulation 29 (demolition or dismantling): planning and recording of arrangements. Regulation 31 (excavations): planning and execution. Regulation 32 (cofferdams and caissons): design, planning and execution. Regulation 36 (temporary traffic management): on any part of the highway any temporary traffic management design should be designed to incorporate the Principles of

Chapter 8.

Temporary Works – What the guidance says

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BS 5975:2008+A1:2011 – CoP for temporary works procedures and….

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SIM 02/2010/04 – Management of temporary works in the construction industry

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BS EN 12812: 2008 – Falsework – performance requirements & general design

Temporary Works – Guidance Ideal TW Procedure (from BS 5975) •

Appointment of a Temporary Works Co-ordinator (TWC).

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Completion and Maintenance of a Temporary Works Register.

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Preparation of Design Briefs for Elements Identified in Register.

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Production of Temporary Works Designs.

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Independent checking of the temporary works design

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Pre-erection / Instillation Inspection of Materials & Components.

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Supervision of Erection / Installation of Temporary Works.

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Inspection & Check of Temporary Works Prior to Use.

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Approval – Permit to Load – (Temporary Works Loaded).

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Approval to Dismantle Following Checks – Permit to Dismantle.

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Temporary Works Dismantled and Signed Off.

Temporary Works – Guidance TW Coordinator TWC is responsible for ensuring that the organisation’s procedure for the control of TW is implemented on site TWC must have adequate authority to carry out their tasks including stopping the work if necessary Depending upon size of the project might be supported by Temporary Works Supervisors

Temporary Works – Guidance TW Coordinator •

Coordinate all temporary work activities

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To determine the temporary works for a project and compile a TW register and keep all temporary works records.

• To determine the type and risk class of temporary works on a project. • To ensure that the responsibilities in relation to temporary works are clearly allocated, defined and understood by all parties and that each party is competent to carry out their responsibilities. • To ensure that all temporary works are designed and checked appropriately. • To ensure that all temporary works activities are adequately planned and supervised.

Temporary Works – Guidance Design Brief

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Purpose of temporary works – including drawings of permanent works and any specifications.

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Required dimensions and any known constraints.

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Ground conditions, information on soils, groundwater etc provide geotechnical information.

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Site conditions, including services, adjacent structures and access.

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Available materials and equipment.

Particular loads including impact loads - loadings from construction material, plant and personnel and environmental loads.

Construction sequence and loading stages

Temporary Works – Guidance Design Checks Before erection commences, the temporary works design should be independently checked for:

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Design concept Strength and structural adequacy Compliance with the design brief

Recommendations on the independence of the checker are given in BS 5975

Temporary Works – Guidance TW Register Should contain:• Design brief number. • Short description of temporary works. • Date required for design solution. • Risk category of temporary works. • Designer. • Design Checker. • Dates – design complete/checked, erection completion, permit-to-load.

Temporary Works

What sort of questions might we ask?

Temporary Works Do you have a formal TW procedure? Who is the named TWC? What is their background? Do you have a TW register? Is there a design brief?

Temporary Works Has the work been ‘designed’? Has the design been independently checked? What checks have been made to ensure that the works have been installed in accordance with the design? What involvement has the CDM-C had?

Temporary Works

What do we hope to see?

Temporary Works Attention to temporary works management arrangements and procedures…. ….commensurate with the scale and complexity of the project and the construction risks involved Medium / large projects – formal procedures Small, simple projects – principles of BS5975

Temporary Works

What have we been finding?

Temporary Works

For the larger projects, then normally

some form of TW procedure. Some follow BS5975 quite closely, some follow the principles. But not much involvement by CDM-Cs

Temporary Works And for the smaller projects…? At best, a recognition that TW can be hazardous and needs particular attention But more often…….

Temporary Works “I don’t see what the problem is….”

Adequately supported?

Adequately supported? “…..I’ve been in this game for 40 years”

Anyone for Jenga?

Temporary Works

Temporary Works

Temporary Works “Erm, no, I’ve not spoken to an Engineer”

Temporary Works

Temporary Works – Common problems

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Lack of adequate lateral stability Inadequate foundations Overloading Inappropriate parts being used Poorly designed (if at all) Poorly constructed

Temporary Works – Common problems

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Workforce not competent for tasks required

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Don’t appreciate the true force of wind

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Changes made ad hoc

No investigation of existing conditions (ground, services, structural condition etc) General lack of control, management and supervision

Temporary Works

Temporary Works

References •

Temporary Works Principles of Design and Construction by ICE

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BS 5975 Code of Practice for Temporary works HSE SIM 02/2010/04 The management of temporary works in the construction industry

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SCOSS Standing Committee on Structural Safety Falsework: Full circle? http://www.scoss.org.uk/publications

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Temporary Works Forum (TWf) www.twforum.org.uk

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Additional slides if time permits:

Temporary Works

The accident statistics don’t suggest that we have a worrying problem with civil engineering type projects

Temporary Works

But accidents still happen…..

FATALITY: DRAINAGE TRENCH COLLAPSE, CWMBRAN 2003

FATALITY: DRAINAGE TRENCH COLLAPSE, CWMBRAN 2003

OVERTURNED PILING RIG, HULL 2007

OVERTURNED PILING RIG, HULL 2007