The LWF Blog

Fire Engineering for Healthcare Premises – Evacuation Time – Part 26

March 15, 2021 12:22 pm

In LWF’s blog series for healthcare professionals, our aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 25 of Fire Engineering for Healthcare Premises, LWF began to look at the human factors relevant when considering evacuation from a building. In part 26, we will continue looking at building occupants and evacuation.

When looking at the evacuation of a healthcare building, or part of, the speed of movement of building occupants should be considered. Total evacuation time is comprised of pre-movement time and travel time. Walking speed is only one component of travel time.

The ability of a person to move at a certain speed during evacuation is not a given and particularly in a healthcare environment, the walking speed of an individual could vary greatly from the next. For dependent or highly dependent patients, it is likely that the walking speed could be very low and they may also be forced to rely on assistance from staff during evacuation.

Very high dependency patients may be unable to move at all, and indeed, they could be unaware of the evacuation taking place if they are not conscious. The challenges of moving dependent, highly dependent and very high dependency patients in an evacuation situation must be addressed and the methods employed detailed in staff training.

Doorways can provide additional challenges during evacuation. It cannot be assumed that the movement of persons through a doorway will be smooth and uninterrupted and result in the optimal evacuation time possible.

Although more detailed analysis is possible and may be advisable, an estimate of movement through doorways can be gained by assuming the widest door in place is unusable due to the fire situation and extrapolating the estimated evacuation time from that potential situation.

Movement along stairs must also be calculated separately to movement along horizontal corridors. Stairs cannot be calculated in the same way as horizontal movement, in terms of their length. To do so would be to wrongly assess the number of persons who can occupy the stairway at one time and would not provide a correct speed/density relationship.

Patients who are dependent or highly-dependent will not be able to manage the stairway without assistance from staff and this must also be encompassed into calculations of travel time.

In Part 27 of LWF’s blog series, LWF will look at the effects of smoke on movement, tenability limits and exit choice. 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 for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact LWF on freephone 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.

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