Stafford & Shropshire WWT Temporary Works Seminar Works 11 Sept 13- Andrew Rattra… · Stafford & Shropshire WWT Temporary Works Seminar ... “Code of practice for falsework”

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

• 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)

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

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


• 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.


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

• 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

• Increasing awareness of the importance of managing temporary works effectively

– Supporting events like today

• Checking on contractors’ management arrangements for temporary works

• 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 saysThe small print

CDM Regulations 2007 and the ACOP specifically mention temporary works:

• “Structure” means… “any formwork, falsework, scaffold…” (Reg2(1))

• “Designers therefore include: ... temporary worksengineers…” (para 116)

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

• “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 worksdesigners…” (para 104)


CDM2007Regulation 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 pre-

construction 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).


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

• BS 5975:2008+A1:2011 – CoPfor temporary works procedures

and….

• SIM 02/2010/04 – Management

of temporary works in the

construction industry

• BS EN 12812: 2008 –

Falsework – performance requirements & general design

Temporary Works – GuidanceIdeal TW Procedure (from BS 5975)

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

• Completion and Maintenance of a Temporary Works Register.

• Preparation of Design Briefs for Elements Identified in Register.

• Production of Temporary Works Designs.

• Independent checking of the temporary works design

• Pre-erection / Instillation Inspection of Materials & Components.

• Supervision of Erection / Installation of Temporary Works.

• Inspection & Check of Temporary Works Prior to Use.

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

• Approval to Dismantle Following Checks – Permit to Dismantle.

• Temporary Works Dismantled and Signed Off.

Temporary Works – GuidanceTW 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

• 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 – GuidanceDesign Brief

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

• Required dimensions and any known constraints.

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

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

• Site conditions, including services, adjacent structures and access.

• Available materials and equipment.

• Construction sequence and loading stages

Temporary Works – GuidanceDesign Checks

Before erection commences, the temporary works

design should be independently checked for:

• 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

• Lack of adequate lateral stability

• Inadequate foundations

• Overloading

• Inappropriate parts being used

• Poorly designed (if at all)

• Poorly constructed

Temporary Works – Common problems

• Workforce not competent for tasks

required

• Don’t appreciate the true force of wind

• No investigation of existing conditions

(ground, services, structural condition etc)

• Changes made ad hoc

• General lack of control, management and

supervision

Temporary Works

Temporary Works

References

• Temporary Works Principles of Design and Construction by

ICE

• BS 5975 Code of Practice for Temporary works

• HSE SIM 02/2010/04 The management of temporary works in the construction industry

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

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

• 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

Documents

Stafford & Shropshire WWT Temporary Works Seminar Works 11 Sept 13- Andrew Rattra… · Stafford & Shropshire WWT Temporary Works Seminar ... “Code of practice for falsework”