Study finds construction workers put their lives at risk by ignoring alarms

HIGH rise construction workers are ‘risking their lives’ by not treating evacuation alarms seriously enough, according to new research.

Researchers from the University of Greenwich, funded by the Institution of Occupational Safety and Health (IOSH), found that a third of workers who took part in evacuation trials spent over a minute finishing the task they were working on – with the longest time to respond to an alarm being six minutes.

It was also discovered that more than two in five needed their supervisor to tell them to leave the site, while many believed their employer viewed finishing the task as more important than evacuating immediately as the alarm sounded.

The research, called Construction site evacuation safety: evacuation strategies for tall construction sites, is the first of its kind with no prior studies existing on the behaviour and performance of construction workers during evacuations.

The study was conducted on two different sites in London, where four full-scale unannounced evacuation trials involving a total of 932 workers were analysed by researchers. Evacuation times from the buildings ranged from nine minutes and 14 seconds to 20 minutes and 47 seconds.

It was found that workers located within the formworks of a building respond to an alarm differently to those in the main building; the mean time to respond to an alarm for those working in the main building was 71 seconds, while in the formworks it can be as low as 30 seconds.  Researchers found that 32% of workers in the main building took over a minute to ‘disengage from their pre-alarm activities’.  The average time for supervisors located in the formworks to disengage was only 5.9 seconds which, according to the report, was ‘an example of the performance of well-trained and highly-motivated staff’.

82% of those who answered the accompanying questionnaire said they knew what an evacuation alarm meant (to leave immediately) however, only 49% said their first action was to leave. Four in five said they were prompted by an alarm, but video evidence taken during trial evacuations at the site suggested 43% required supervisor intervention.

The report recommends enhanced training and greater enforcement of evacuation policies to ensure workers react promptly to alarms, as they speculate that workers may not be entirely sure what is meant by ‘evacuate immediately’.

Professor Ed Galea, who headed up the research team in the Fire Safety Engineering Group at the University of Greenwich, said, “In an emergency evacuation situation, each second can make the difference between life and death. A delayed response poses a significant risk to the health and safety of workers who might need to be evacuated due to a fire, or another on-site emergency.

“One unexpected finding was that workers were not impacted by construction height. This means that people on higher floors and those on lower floors had similar response times. A worker on the 30th floor did not necessary respond to an evacuation alarm any quicker than a worker on the fourth floor.

“This research shows that it is essential to have robust plans in place to ensure the safe and timely evacuation of workers, and it will aid the development of improved procedures and advance the safety of people working on high-rise construction sites.”

Duncan Spencer, head of advice and practice at IOSH, said, “The outcomes from the research will help to improve the safety of construction workers in emergency evacuation when operating in tall building construction environments, by providing a series of suggested improvements and recommendations to be followed by businesses.

“It is clear that these improvements are needed considering that this is one of the most challenging scenarios particularly given the ever-changing nature of the construction site. Response times are slow in many cases. Workers should be evacuating immediately when they hear an alarm, rather than wasting precious seconds on finishing a task. If they don’t do so, they are risking their lives because every second counts in an emergency.”

The trials took place at 22 and 100 Bishopsgate, both of which are being constructed by Multiplex. The firm has already moved to develop and enhance its safety processes.

Martin Wilshire, Multiplex health and safety director, said, “The research undertaken by Ed Galea and his team on our high-rise projects has highlighted the importance of challenging established industry ‘norms’ and their origins in creating relevant guidance around safety during tall building construction.

“From our involvement in this work, we have gained a greater understanding of evacuee behaviour and the impact of access constraints such as falsework and surfaces under construction which are unique to our industry. The detail in the research will better inform our approach to risk assessments, particularly in planning for means of escape and improving behaviours in an evacuation scenario.”