Topic B - Temporary Works

temporary works

any works that are needed for construction activities, but are not part of the final works

temporary works

“works designed by or on behalf of the contractor to enable the permanent works to be constructed safely and w/o harming the environment, by providing protection, support or access and which might or might not be left in place after completion of works”

key points for temporary works

1. responsibility for designing TW lies w/ contractor, not project designer

2. TW may be required for safety reasons (scaffolding for safe access)

3. TW may be required for environmental reasons (water settlement ponds)

4. TW are often removed once their need is over (left in place if unsafe/expensive to remove)

safety, time, cost, reputation

why are temporary works important?

regulation of TW

there have been multiple high profile temporary works failures, often involving fatalities

Advisory Committee on Falsework

landmark UK committee established in 1973, chaired by Stephen Bragg. It was formed following several high-profile and fatal bridge collapses (such as the Loddon Bridge collapse) caused by the failure of temporary structures.

Final Report of Advisory Committee on Falsework

The Bragg Report (1975): A seminal safety report that established the modern framework for falsework design, execution, and supervision. Its most significant contribution was the mandatory requirement for a Temporary Works Coordinator (TWC) to oversee all aspects of temporary structures, ensuring clear lines of responsibility to prevent structural failure.

technical faults which led to collapse, procedural error which allows the technical faults to occur and go undetected/corrected

two elements in cause of each collapse

BS5975

technical recommendations for design of falsework and other temporary works structures

requirement to manage risk: procedure to manage risk

British Standard that provides the code of practice for the procedural control of temporary works on construction sites. It is considered the "Industry Bible" for ensuring site safety regarding scaffolding, falsework, and shoring.

technical faults

insufficient consideration of :

1. horizontal stability

2. progressive collapse

3. overloads

4. inadequate foundations

5. beam supports

6. tolerances & eccentricities

7. setting out accuracy

8. material quality & defects

9. dismantling

procedural errors

1. failures of communication

2. inadequate design briefs

3. inadequate drawings

4. designer not consulted on changes

5. failure of inspection

6. designs not checked

7. falsework not checked for compliance w/ design prior to loading

legislation, standards & codes of practice

How do we prevent TW failures?

construction: design and management

defines legal duties of organisations and individuals

1. clients

2. designers

3. contractors

4. workers

client responsibilities

ensure other duty holders are appointed

sufficient time and resources

relavant information is provided to duty holders

welfare facilities are provided

designer responsibilities

eliminate, reduce, control unstable risks

construction

maintenance and use

provide information to other duty holders

principal designer responsibilities

plan manage, monitor & cordinate health & safety in the pre construction phase of a project

ensure designers carry out their duties

provide information to other duty holders

liase w/ client & principal contractor

principal contractor responsibilities

plan manage, monitor & cordinate health & safety in the construction phase of a project

contractor responsibilities

plan, manage, monitor construction work under their control

so it is carried out w/o risks to health & safety

coordinate activities with/ other contractors

worker responsibilities

must

be consulted about matters which affect their health & safety

take care of their own & others H & S

report any risks to H & S

cooperate w/ other duty holders

procedure to manage TW on site

1. appointment of TWC [Temporary Works Coordinator]

2. preparation of adequate design brief

3. completion & maintenance of TW register

4. production of TW register

5. independent checking of TW design

6. issue of desing/design check certificate

7. pre-construction inspection of TW materials & components

designated individual

senior management: ultimate legal responsibility for company’s safety procedures

main job: establish company’s policy for TW and ensure enough resources

key action: officially appoints TWC and TWS: ensure are competent and have appropriate training

Temporary works coordinator [TWC]

primary point of contact for temporary works on a projcet

main job: coordination, make sure there is a design for TW, design is externally checked, site team follows design

Permit to Load, Permit to Dismantle

PC’s TWC

on large site, many contractors - PC’s TWC sits above for centralised organisation and understanding

Main job: overarching management

Liaison: ensure each organisation is following the project-wide TW regulations

Temporary Works Supervisor

main job: supervision of physical work, ensure erection of formwork/falsework matches drawings exactly

daily inspections

Gerrads Cross failure

1. Inadequate communication of the complex design & construction method

2. Selection of least engaged contractor w/ lowest quote

3. Inadequate review of change from using one type of fill material to two

4. Lack of appreciation of warning signs of collapse

5. Temporary application of fill on crown for road over [contrary to method statement]

TW for upgraded flood defences

1. platform above the river

2. supports for existing wall

3. netting to prevent debris going into river

4. divert the river

5. pedestrian/traffic diversions

6. compound for materials and plant

7. crane - install precast elements

8. hardstanding support for crane

TW for bridge over railway

CAT scan to identify services

excavation support (sheet piles)

compound, storage, welfare units, office space

hardstanding for crainage & heavy plant

scaffolding (access to top of abutment)

formwork (construct abutment)

access to other side of railway (access roads)

falsework and formwork to support deck construction

TW for reservoir

falsework for roof

battered sides of excavation

formwork for concrete wall

scaffolding to get to the top

edge support

foundation support for tower crane

vehicle access separated from pedestrian routes