CROSS Safety Report
Scaffolds and traffic protection
This report is over 2 years old
A reporter is concerned about the lack of consideration shown both in British Standards and industry guidance regarding the risk of impact of vehicles with scaffolds and thereby putting at risk those working on a scaffold.
Key Learning Outcomes
For all built environment professionals:
Where scaffolds are erected adjacent to public highway, adequate barriers should be provided to prevent impact from vehicles
It is good practice to carry out a site specific risk assessment for each case
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A reporter who is a local authority structural engineer is often consulted about, and sometimes has to arrange for, scaffolds to be erected on the public highway, or at least within close proximity of vehicular traffic. What amazes him is the lack of consideration shown both in British Standards and industry guidance regarding the risk of impact of vehicles with scaffolds and thereby putting at risk those working on a scaffold and those in the vicinity should a collapse or partial collapse occur.
Lack of guidance
For many years the reporter has only been able to justify the need to consider and provide protection by producing a designer’s (site-specific) risk assessment. They have never been able to find or cite the recommendations of a good practice guide, or British Standard requirement. When arguing a case for protection being provided (some contractors/clients are so blinkered to thinking through hazards that unless they can be shown a reference, they believe it is not something that needs considering).
Neither the old BS5973 scaffold standard, nor its new EN replacement, mentions the need to consider accidental impact. Chapter 8 for Highways is only concerned with signing/traffic management. Even the Health and Safety Executive (HSE) guidance notes fail to highlight this, in particular their guidance on Construction Site Safety fails to mention in ‘safe consideration for site roads’ the need to consider proximity to scaffolds.
Neither the old BS5973 scaffold standard, nor its new EN replacement, mentions the need to consider accidental impact
The reporter’s authority has always insisted that for scaffolds they organise themselves (usually for a structural inspection of a building/bridge), they have some form of physical barrier such as temporary precast concrete units, or water filled units or even timber sleepers strapped together; all spaced at least 500mm away from the scaffold to allow deflection/impact absorption to occur without contacting the scaffold. This would be say for a 30mph city centre location. Higher speed roads or heavier/larger vehicle access may need higher specifications, resident car parks to the rear of blocks of flats may need less.
Expert Panel Comments
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This is an important subject given the possibility for multiple fatalities and the HSE have suggested that it could be addressed and that a current research project on the use and selection of temporary motorway barriers may assist with this. However, they point out that risk assessments will still be required and the guidance or advice should not be mechanistically prescriptive.
In April 06 a 14 storey scaffold collapsed in Milton Keynes resulting in a fatality and two injured workmen. The cause is not yet known but it prompted HSE to issue an alert about scaffolding and possible vehicle impact was mentioned. The Highways Act requires a licence in writing for scaffolds and similar structures on highways and adjacent footways and the Highway Authority has the duty to impose such conditions as it considers necessary.
The Highways Act requires a licence in writing for scaffolds and similar structures on highways and adjacent footways and the Highway Authority has the duty to impose such conditions as it considers necessary
Specific reference to impact protection is to be found in the following documents:
- Scaffolding TG20:05 (NASC) states, "Scaffolds are vulnerable to damage from impact, overloading, wind loads and unauthorised modification" (page 27)
- Facade Retention CIRIA Report, C579, on Retention of masonry facades has some observations on "Impact Loads" (Page 155 and 156, Clause 8.5)
- Falsework BS5975: 1996 (as amended) states: "The effects of dynamic and impact forces on falsework should be evaluated and allowed for in the design ... Where possible, such impact forces should be minimised or avoided ... It is always preferable to prevent accidental impacts from occurring rather than to strengthen the falsework to resist them..." (Clause 22.214.171.124)
In addition, CIRIA Report 579 has some observations and proposals for protection, with reference to temporary facade retention systems in general, and with some specific reference to scaffolding.
Other views on the protection of scaffolds and similar structures will be welcome, particularly on the need for additional guidance. The Institution of Structural Engineers (IStructE) Advice on Temporary Structures which will be published soon is expected to warn against vehicle impacts and draw the attention of designers and constructors to planning against such eventualities.
Whereas it is the case that those who design and work with scaffold are obliged to consider relevant hazards, it would be useful to reinforce the message in industry guidance, British Standards and the like. This would assist those cases in particular where standard temporary works are used with no recognisable design input and CROSS will be looking at this.
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