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#1 Posted : 02 March 2007 14:43:00(UTC)
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Posted By Declan Roche
Hi

I know this has come up repeatedly, but I cannot find the answer on any of my searches of the forums.

I am looking for a guideline for the appropriate time to clear a multi-tenanted, modern compartmentalised building in an Evacuation Drill. A Fire Warden Trainer who works for one of the Tenants has stated that the maximum permissible time for completion of a fire drill is 2.5 minutes, however as it takes 2 minutes 20 Seconds to briskly walk from the furthest point in the building to the Assembly point I do not think this is ever going to be achieved.

I have seen various recommendations that the time taken should be 2.5 minutes, 5 minutes, 2.5 times the time to walk the distance and also 1.5 times the distance. I cannot find anyone, including my local Fire Brigade to give a definite recommendation.

Does anyone know of a specific recommendation or guideline by a Competent Authority or is this just one of those things that is made up as we go along?

Any help would be greatly appreciated!
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#2 Posted : 02 March 2007 16:24:00(UTC)
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Posted By Darren J Fraser
I have never come across anything with a 'permissible' time for evacuation.

I always base my times on achieve-ability.

For example, to evacuate a small garage of 5 people should take less time than to evacuate a 3 storey call centre.

I would suggest that you time a normal pace walk from the furthest point to the assembly point, if it takes 2.5 minutes, then aim for an evac time of between 4 and 5 minutes, if you are going to include a roll call or similar into your evac time then adjust accordingly. Would also look at how long it will take for the emergency services to arrive, if they are there in 2 minutes you may still be evacuating, possible into their direct approach route, therefore is the assembly point in the right location. Would 2 or 3 assembly points be a better solution, taking into account possible communication issues.

May seem to ramble a bit, but hopefully you get the jist.
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#3 Posted : 02 March 2007 16:51:00(UTC)
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Posted By GARYS
Declan

I can't remember where I have seen it quoted, but I've always been of the option that it is best practice to be able to evacuate a building in less than 3 minutes. Now that is to get out of the building via a final exit to safety i.e. outside not to the assembly point.

Sorry I couldn't be more specific
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#4 Posted : 02 March 2007 17:23:00(UTC)
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Posted By Frank Newman
This is Merv

A single storey building with a couple of hundred people in it can be emptied of people within 3 minutes. Walking (not running) to the control points could take another few minutes. Depends on the distances. Sweeps should be coming out at about the same time the last people get to the control points.

There can be no typical target time. I hate to remind people, but think of 9/11

The other point is that in an emergency evacuation I do not want people to rush. If they are out of immediate danger then they stroll. But they don't go back for their handbags or umbrellas.

I ran twice-a-year drills for almost twenty years. Never got a 100% perfect. People ! Why do we have to employ them ?

Merv
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#5 Posted : 03 March 2007 00:33:00(UTC)
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Posted By shaun mckeever
There is a typical time limit. Exit widths and travel distances are based on the time of travel to an exit and number of people that can pass through an exit width in a given time. 2.5 minutes is the typical time to exit a room and reach a place of relative safety i.e. a protected route.
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#6 Posted : 03 March 2007 06:58:00(UTC)
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Posted By GT
Declan,
Shaun is correct in his statement and I believe that there are two other times based on the risk assessment of the building i.e 2 and 3 minutes the lesser the risk (speed of fire development) the longer you have to evacuate. There are some people on the forum suitably qualified to conduct this assessment and do it as a profession, Shaun I think is one such person.

Regards

GT
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#7 Posted : 03 March 2007 20:59:00(UTC)
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Posted By shaun mckeever
Thanks for the compliment GT. You are right, in very low risk premises a typical evacuation time of 3 minutes to a place of relative safety may be acceptable and in high risk premises a typical time of 2 minutes is normal. All of this must of course be weighed against the risk and in some circumstances, such as a fireworks factory, even two minutes might be too long.
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#8 Posted : 04 March 2007 13:19:00(UTC)
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Posted By Pugwash
I find that people often confuse the time for everyone to reach a protected stairway with the time for everyone to leave the building. As Shaun states, 2.5 mins is a reasonable time for the former, but the time for latter will depend on the height of the building - it could be more than 30 minutes in some cases. You should be concerned if people are queuing to get INTO a protected route after 2.5 mins unless the fire evacuation strategy for the building explicitly permits this (because of compensating fire engineering features in he building).
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#9 Posted : 04 March 2007 15:39:00(UTC)
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Posted By Charley Farley-Trelawney
http://www.iosh.co.uk/in...=1&thread=21299&page=201

Some interesting posts for the evacuation times with some varied notions, including mine it seems!
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#10 Posted : 15 March 2007 08:15:00(UTC)
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Posted By Troos Jacobs
Hi Declan,

I found your discussion very interesting as i am busu with evacuation and disaster management for 28 years.
I hope he following points will assist you with a guide to estimate evacuation times.

1. What is the type of occupation? Hospitals will be different that offices.
2. Are their any aditional hazards for instance haxadrous gasses ?
3. Buildings must have emergency escape routes that are fire resistant and smoke free ? Different countries different specifications. Check your local specs.
4. Any evacuation drill will be different with the shortest time and minimum injuries.
5. Panic must be prevented at all times. I have my own explanation to prevent panic. Knowledge will prevent panic.

Example:
I am a skydiver, experience two cut aways both times i react on my training and the situation and land safely.
Evacuation out of buildings or out of a disaster area will depend on the same principal. What is the training of the people involved in that specific situation.
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#11 Posted : 15 March 2007 09:28:00(UTC)
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Posted By TBC
Again Shaun is quite correct in his times. One of the usual problems associated with getting the drill to run smoothly is to encourage and educate personnel to use all the evacuation routes - not just the usual way in route. So those final doors must spring closed behind the last one out.
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#12 Posted : 15 March 2007 09:48:00(UTC)
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Posted By Merv Newman
TBC,

I'm not sure about "doors springing closed" A far as I am aware the only requirement is that they should be easily opened.

As far as being instructed "do not panic" that is a total joke. In an unknown, unfamiliar, life threatening situation people panic. How many times have we read of bodies being trampled by hundreds trying to get out of a burning building. You can't help it.

I just know that I will climb over your head to get my wife and kids out the next time the local disco burns down.

The only remedy against panic is regular exercises. So that reaction to the fire bells is routine and totally boring.

Merv
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#13 Posted : 15 March 2007 13:11:00(UTC)
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Posted By Dave Dowan

Dear All
This what I was taught

Evacuation time
The time it takes a person to travel from any occupied
part of the building to a place of ultimate safety.
Consists of 3 principle elements
- Recognition time
- Response time
- Travel time

Evacuation time

Generally accepted as:
• Class A construction ( complies mainly with current regs)
- 3 minutes

• Class B construction ( does not comply )
- 2.5 minutes

• Class C construction (combustible)
- 2 minutes



Regards Dave
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#14 Posted : 15 March 2007 13:42:00(UTC)
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Posted By Jason Warren
There are some good points made here and I am sure that you have all there answers you need. I believe the 2.5 minute rule came from a document called A Guide to Fire Precautions in Existing Places of Entertainment and Like Premises. It was often called the yellow book. It is now out of print.

In this document it classifies buildings into 3 types:

Class A - complete noncombustible construction, i.e. elements of structure, floors, and walls. Supporting structure of brick or concrete;
Class B - traditional construction, i.e. noncombustible walls with combustible floors;
Class C - combustible construction, i.e. timber floors and walls.

For each type it gives a suggested escape time:

Class 'A' construction - 3 minutes
Class 'B' construction - 2.5 minutes
Class 'C' construction - 2 minutes

These times were meant as a guide. The current Legislation relies upon a risk assessment approach considering your structure, internal layout, processes and activities taking place, numbers of occupants, types of occupants etc.

Although this is an out of print document I have always used the times as a reference. The time should be measured from the furthest point to a place of safety. This is generally an external point which leads away from the danger. If the building is large then measure to a place of relative safety ie a different fire compartment, fire escape staircase etc.

Hope this was useful. Regards, Jason


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