The LWF Blog
Fire Safety Engineering for Design – Means of Escape Design – Part 107November 14, 2022 11:53 am
LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 106, LWF discussed lift lobbies and refuge floors. In part 107, we consider the use of escalators during evacuation.
It would be unusual in a standard building, such as an office block to find escalators used at all, never mind as a part of the evacuation route. However, as a method of exiting an underground station, for instance, they are ubiquitous.
An escalator is, in essence, a motorized moving open stairway that transports people from one level to another. At an airport, you might find moving walkways, which are the same principle and design as an escalator but they transport people horizontally rather than up and down.
For some facilities, escalators provide the primary means of escape. It is important that the escalator will not discharge its passengers into an area affected by fire, or into a closed-off area. Closed-off areas are possible if there are shutters which become operational when the fire alarm triggers.
Where escalators form a part of the escape route, they must provide a safe route to a place of safety outside.
Current UK codes, including ADB Volume 2 or BS 9999, do not recognise the use of escalators as a part of means of escape, but if the escalator discharges into a low fire load area then they may be considered acceptable as an exit route.
The advantage in acceptance of escalators is that if people used a certain method to gain entry to a facility, they will likely attempt to use it again to get out.
When assessing the capacity of an escalator as a part of the escape route, it should be assumed that the mechanism will be stationary, unless a secure/secure backup power supply is to be provided.
The riser and tread dimensions of escalators are not as per stairs and therefore, movement is not as easy when they are at a standstill. The flow capacity may be taken as 56 persons per minute per metre width, a measurement taken between the innermost part of the handrails.
More information may be gained from NFPA 130 which specifies fire protection and life safety requirements for underground, surface and elevated fixed guideway transit and passenger rail systems. It is a U.S. standard, although used widely elsewhere.
In part 108 of LWF’s series on fire engineering we will … In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.
Lawrence Webster Forrest has been working with their clients since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.
While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.