Tag Archives: emergency services

High-rise external evacuation

A quick googling turned up this great idea, using an escape chute attached to the top of a fire crane. The chute has a fireproof external layer and people slow or speed their descent in it simply by varying their posture. Read the pdf for more details:

http://www.escapeconsult.biz/download.php?module=prod&id=26

But the picture tells all you need to know. You can see it reaches very high, up to 100m with the tallest fire appliance.

It is a great idea, but you can still see how it could be improved, and the manufacturer may well already have better versions on the way.

Firstly, the truck is already leaning, even though it has extendable feet to increase the effective base area. This affects all free-standing fire rescue cranes and ladders (suspension ladders, or ladders able to lean against a wall obviously include other forces). Physics dictates that the center of gravity, with the evacuees included, must remain above the base or it will start to topple. The higher it reaches and the further from the truck, the harder that becomes, and the fewer people can simultaneously use the escape chute. Clearly if it is go even higher, we need to find new ways of keeping the base and center of gravity aligned, or to prevent it toppling by leaning the ladder securely against a sound piece of wall that isn’t above a fire.

One solution is obvious. Usually with a high-rise fire, a number of fire appliances would be there. By linking several appliances to the ladder in a stable pattern, the base area then becomes far larger, the entire area enclosed by the combined appliances. At the very least, they can spread out across a street, and sometimes as in the Grenfell Tower fire, there is a lot of nearby space to spread over. With a number of fire appliances, the crane is also not limited to the carrying capacity of a single appliance.

If theses are specialist hi-rise appliances, one or two would carry telescopic arms to support the rescue equipment, with one or more trucks using tension wires to increase the base area.

We also need to speed up entry to the chute and preferably make it accessible to more windows. The existing system has access via a small hole that might be slow to pass through, and challenging for larger people or those with less mobility. A funneled design would allow people to jump in from several windows or even drop from a floor above. Designing the access to prevent simultaneous arrivals at the chute is easy enough, even if several people jump in together

Also, it would be good if the chute could take evacuees away from the building and flames as fast as possible. Getting them to the ground is a lesser priority. Designing the funnel so it crosses several windows, with a steep slope away from the building (like an airplane escape slide) before it enters the downward chute would do that.

Another enhancement would be that instead of a broad funnel and single chute, a number of chutes could be suspended, with one for each window. Several people would be able to descend down different chutes at the same time. with a much broader base area, toppling risk would still be greatly reduced.

If a few support arms could be extended from the crane towards the building, that would provide extra stability until their strength (or building fabric) is compromised by fire. Further support might sometimes be available from window cleaning platform apparatus that could support the weight of the rescue chutes. If emergency escape chutes are built into the platforms could even make for an instant escape system before fire services arrive.

With these relatively straightforward enhancements, this evacuation system would be even better and would allow many people to escape who otherwise wouldn’t. OK, here’s a badly drawn pic:

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