How temporary works can benefit construction projects

New guidance highlights how temporary works can improve the constructability of building and infrastructure projects and cut overall costs.

Installing structures during construction that won’t remain in the finished building or infrastructure may not sound cost effective, but temporary works can improve sequencing, as well as reducing the risk of programme and cost overruns when work progresses onto site.

“While this approach is tried and tested, it calls for early engagement and extensive design and construction experience to maximise the benefits,” says Alan Willoner, technical director at Mott MacDonald.

Understanding the difference

Temporary works enable construction of permanent works by protecting, supporting or providing access. They can include elements of the permanent works that are temporary, such as short-term loading conditions, as well as structures that undergo modification or demolition.

These temporary structures might not remain in the permanent works, but the attention to detail and design rigour is the same as that used in the final structure. The difference is that permanent works are likely to require a 120-year design life, but temporary works may only exist for days, weeks or months.

Creating savings and certainty

Recently, Mott MacDonald delivered a £1.2m saving compared with taking a conventional approach when it combined temporary works for geotechnical solutions with the observational method that adjusts construction process based on real-time monitoring of the ground and structure’s behaviour. By constructing a new underbridge below an existing railway during a track possession in this way, the project team gained certainty about how long the work would take. If they had taken an approach focused on the permanent works, it would have meant a longer line closure.

What’s the latest guidance?

Two codes of practice were published on 31 December 2024 that incorporate the latest technical advancements and best practice:

• BS 5975-1:2024 Temporary works – Management procedures for the control of temporary works
• BS 5975-2:2024 Temporary works –  Falsework: Design and implementation

Early collaboration is key

A challenge facing temporary works is the small number of people with the right skills to design and deliver them. The best temporary works designers generally have extensive construction and design experience, but the industry lacks people with experience of both contracting and consulting.

“There are several small specialists with expertise in temporary works design, but these firms are often too low down in the supply chain and brought into projects much later than the designers working on the permanent works. This late involvement limits these specialists’ ability to develop the most innovative solutions that could offer the most gains,” says Mr Willoner.

Early engagement between teams allows them to develop solutions that reduce costs and risks and improve constructability.