Government-commissioned high-rise evacuation research shows second staircases halve exit times

Strategy 3A (Test 3A-2) varied in that a full evacuation using an EAS took place with phased bottom-up from above the fire. Approach 3B (Test 3B-2) trialled a phased top-down from above the fire.

However, the results were most pronounced in strategy four (Test 4-2), where a full simultaneous evacuation took place using an EAS and two staircases.

When using two staircases (one for evacuation and one for firefighting), evacuation times were shorter than for all other evacuation strategies.

Strategy one and for both tested full evacuations with an EAS. However, Test 4-2 (with two staircases) was completed in nine minutes and two seconds, approximately half the time of Test 1-1 which completed in 19 minutes and 15 seconds.

A disused 17-storey tower block used by LFB for various exercises was selected for the evacuation tests as an example of a typical UK HRRB.

The findings come as the housing secretary announced in October that developers will have a transitional period of two-and-a-half years before they have to put a second staircase into buildings that are 18 metres or taller.

The mayor of London had previously stated that plans for new tall residential buildings in London will need to incorporate a second staircase in order to be signed off.

For each test, the fire started on the sixth floor and was assumed to spread upward to floors seven and eight. FRS stairwell protection teams (SPTs) initiated the evacuation tests based on the standard operating procedures (SOPs).

For operational decision-makers, the findings indicate that using an EAS (strategy one) resulted in faster evacuation than a door-knocking system (strategy two). The difference in these two instances showed evacuees in the second strategy leaving the building more than eight minutes longer than in the first.

The Home Office said in its summary of the report: “Future research could look to understand the impact of resident awareness of EAS on evacuation effectiveness, as this study’s scoping found that this is an important feature of it working well.”

The findings were not clear in showing whether either a top-down or bottom-up evacuation strategy is faster and which should be preferred during an evacuation. In these tests, evacuation starting from the highest floor above the fire completed in less time than bottom-up, where evacuation began from the first feasible floor above the fire. 

However, due to the confounding variables in participants’ profiles – such as the number of participants and the amount instructed to walk at half pace – further testing would be required to establish robust conclusions.

The findings also suggested that people evacuating other residents on evacuation can delay the movement of those evacuees behind them. Such delays may also be affected by the degree of familiarity with the evacuation chair equipment and the cumbersome nature of the equipment worn by firefighters

The higher the floor where residents with impairments live, the greater the potential detrimental effect on the evacuation speeds from following evacuees with impairments. 

There was evidence for Tests 1-1, 2-2 and 3A-2 that evacuation speeds may be limited for those starting on higher floors. This is because the transit of evacuees with a mobility impairment appeared to affect the evacuation speed of those joining stairwells from higher floors.

The appropriate evacuation strategy may also vary depending on the evacuee’s specific needs, but this study did not find consistency in how evacuation needs affected speed. For example, it was observed in strategy one that evacuation chairs can move at greater speeds than some evacuees walking with crutches, whereas the opposite was observed under strategy two.

Therefore, the report stated that “it is important to note uncertainty in these findings, given the number of limitations in assessing the impact of participants with impairments”.

The test results act as a reminder that the UK has still not developed new evacuation plans and policies, particularly around taking disabled residents into account. Measures such as fire alarms, sprinklers and personal emergency evacuation plans have still not been decided on by the government.

The findings are at odds with previous government statements, as it announced in May 2022 that it will not implement critical recommendations of the Grenfell Tower Inquiry, which called for legal obligations to plan for the evacuation of high-rise buildings and disabled residents in the event of a serious fire.

At the time, the Home Office said it does not believe it is “proportionate” to follow the recommendations and will continue to place its faith in the stay put advice in most buildings.

Inside Housing previously reported that pushback against the proposed requirement for second staircases failed to grapple with some uncomfortable truths, but the industry is right to ask the government to urgently provide more clarity about what the new rules involve and are trying to achieve.

Headlines have persisted about builders mothballing schemes due to the uncertainty this proposed law has created. A group of 29 fire experts previously wrote an open letter to the government calling for a rethink.

They said the debate was “an unnecessary distraction” that has caused “great turmoil and concerns among those seeking to build homes” and “should be terminated”.

This is because of the faith placed in high standards of ‘compartmentation’ – the idea that fire will be restricted to the flat it starts in for at least two hours, meaning it can be safely extinguished without a mass building evacuation. 

But this was before the Grenfell Tower fire of June 2017. The tower had a single stairwell and when the cladding ignited and multiple fires started inside the building, leading to lobbies quickly being filled with smoke.

Firefighting operations involved doors separating the lobby and the stairs being propped open, and residents fleeing meant other doors were regularly opened.

The stairs filled up with smoke from about 2am, eventually reaching a pitch black concentration of toxic fumes that severely hindered rescue efforts and made it hard or impossible for those still present in the building to flee.

Since that awful night, the idea that it is still OK to build blocks of flats with only one staircase has been subject to increasing scrutiny and criticism.

The Homes Office and the Department for Levelling Up, Housing and Communities have been contacted for a response.