An ‘insight’ into fire evacuations for high-rise construction sites

Lauren Lee

Lauren Lee
Senior Consultant, Assurity Consulting
22nd October 2019

The Institution of Occupational Safety and Health (IOSH) has recently published the findings of a study, funded by themselves, and carried out by the University of Greenwich focusing on fire evacuation drills carried out on high-rise construction sites in London.

Whilst major fires on construction sites in the UK are rare, they do still occur as the Glasgow School of Art’s Mackintosh building fire identifies. It is also estimated that over 500 high-rise building projects are planned for London in the next few years alone.

Thinking about how many workers could be based on a typical high-rise construction site. For a building project of approximately 40 floors, there is capacity for around 1,500 workers based on-site at any one time, with a cumulative workforce estimated at 12,000. Now imagine coordinating an evacuation drill.

The study; ‘Construction site evacuation safety: Evacuation strategies for tall construction sites’, focused on the behaviour of construction workers when carrying out large scale evacuations. Four full-scale evacuations were carried out in 2017 at two high-rise building sites; 22 Bishopsgate and 100 Bishopsgate. The evacuations were carried out at two stages of construction in either building and an additional five walking speed experiments were carried out to establish how walking over different surface types would affect individual behaviour and a timely evacuation.

The results found that whilst over 80% of the workers knew to evacuate immediately upon hearing the alarm, only 43% did so before a supervisor gave direct instruction. Unsurprisingly, a vast number of workers believed that they should finish off their task before evacuating, especially if working on high-priority work. The concern is that some of these individuals were supervisors!

It’s also worth noting that construction workers generally have a higher risk-appetite but also perceive their working environment as safe. Only 33% knew where their nearest fire escape route was, and 21% stated that they searched for directional fire escape signage. Evacuation times improved for the main building when supervisors (the ‘fire wardens’) intervened. However, the evacuation times for formworks were unaffected, due to a single ladder often being the primary means of escape, resulting in congestion. The study then incorporated the use of scaffold dog-leg stairs and fast high-capacity hoists. These additional control measures decreased the building’s evacuation time by approximately 7% and 19%, respectively.

Overall, this study demonstrates the importance of having robust fire safety plans in place. Regular training, staff awareness and the consideration for additional control measures are all fundamental in providing a safe working environment – whether that’s in an office or construction site!