risk of flame spread in BR stations

[terry martin1]

I have recently attended a major BR station that has an issue (or maybe not) that i would value opinions on.

Description:
Concourse surrounded on 3 sides by occupied buildings, 4th side being the platforms and railway lines. The concourse is covered with your typical repeated v shaped glass roof with iron framing and supports (effectively enclosing the concourse).

The concourse has shops clustered in groups spread along the center of the concourse.

They have fitted anti - pigeon netting within the station to an extent I have not seen anywhere else. All of the concourse is covered overhead, they have protected the 'islands' of shops with vertical netting which meets the main netting above and they have covered the ornate fascias of the surrounding buildings.

The netting appears to be a kind of string/hemp or twine (certainly natural fibre and probably quite flammable) and runs very close to, and in places fixes to the various shops illuminated signs.

Would this (in anyones opinion) carry a significant risk of flame spread. bearing in mind if it was to be involved in a significant way it would fall onto the concourse

There is no flammability rating test recorded. and there is no SD within the concourse.

Considering the huge life risk inherent in such a busy station. it would be foolish not to ask the question!

[kurnal]

As you say the first  fundamental is whether the netting is likely to propagate fire across it.
This is clearly going to depend on many factors- the size of the fire source, whether netting is in vertical or horizontal plane, the size of the mesh, the heat output from the strands as they burn, the ignitability of the material, whether the mesh  smoulders or burns with a flame.  

Secondly does it constitute a wall or ceiling lining? if so then standard guidance would apply.

I would suggest that unless the supplier or installer  can provide evidence that it is safe (duty of all suppliers and installers of goods/ services under the Health and Safety at Work Act) then it should be removed and I would start with the vertical sections as a high priority. Was a risk assessment carried out by the supplier?

I would also be cautious about agreeing to ad hoc tests on small samples if this option is offered. It may well be that the heat output from a small sample of material is insufficient to cause the ignition of adjoining strands but the heat output from a significant fire source - say in a shop unit- will supplement this and therefore cause a collapse of the netting over a wide area, impeding safe escape.

[Uncle Dave]

I would suggest that unless the supplier or installer  can provide evidence that it is safe (duty of all suppliers and installers of goods/ services under the Health and Safety at Work Act) then it should be removed and I would start with the vertical sections as a high priority. Was a risk assessment carried out by the supplier?

I would also be cautious about agreeing to ad hoc tests on small samples if this option is offered. It may well be that the heat output from a small sample of material is insufficient to cause the ignition of adjoining strands but the heat output from a significant fire source - say in a shop unit- will supplement this and therefore cause a collapse of the netting over a wide area, impeding safe escape.

I agree regarding ad-hoc tests.  I think that there are standard tests for the sheeting used for cladding scaffolding.  Perhaps that may be appropriate.  (for info on these tests you could try Sheila Warbus at BRE warbuss@bre.co.uk)

Dave

[Andyfire]

This is the problem with train stations and platforms they are now becoming mini shopping malls.
BS 5588 part 10 code of practice section 2.8 describes a covered mall as

a) more than 15m in length covered by bridge or roof.
b) (where the mall has an open slot above it, formed for example by projecting continuous, canopies) more than 50% of its plan area obbscured.

Given that I would suspec that you could call it a mall and all the engineering that goes with it.

in addition it seems to satisfy 2.24(definition of a mall) and 2.36(definition of a shopping complex).

However without looking at the concorse I could not with authority say yea or ney!
However if you look at Waterloo station shopping would seem to be the principle business given the amount of shops there and it being coverd by a roof along with netting..

Seems like a good discussion as Network rail have for to long acted as judge, jury and executioner with regard to safety and the privatisation of railtrack was the best thing to happen as it bought them into the 20th century with regards to working practices.(sorry have experience with them and not good ones)

[jokar]

Now of course they are subject to RR(FS)O with the local FRS acting as the enforcer.  It will be interesting if they have a view of these.

[terry martin1]

Thanks for the views, I didn't think I was being too nit picky.

In response to 'Jokar's' last comment, I should mention I am an enforcing officer (at this point i should state my views in this forum are mine and not necessarily my employers).

 With opinions generally echoing my initial thoughts I would say there is an issue.

I'm not sure if it being a mall or BR station is relevant (apologies if I have missed the point), for me the issue is the netting and its potential to put relevant persons at risk, regardless of its location.

As the netting has not been accommodated within the RA, and (Kurnal kindly pointed out) as there are no docs from the installer. The assumption must be made that it is a significant and more importantly unquantifiable hazard.

the only reasonable way to establish if the netting is, or is not a 'significant hazard' is to carry out a flammability test on the netting in both the horizontal and vertical planes. Although i agree with 'uncle Dave' and 'Kurnal' that the size of the sample is important, I equally value the use of samples taken from source; in my opinion, any material that has been extensively subject to a particular environment could, and in some cases will certainly, act differently from its new unexposed equivalent.  

In short; In the absence of suitable documentation, I believe a flammability test must be the first course of action. With any further response appropriate to the test results.

Any further views/comments

[John Webb]

I suspect that the main problem will be with the method of suspending the netting and its fixtures to the structure.
(a) If metal - little problem - the netting will burn in place, probably only where it is actually in the fire plume and immediately adjacent, as the heat will be insufficient to damage the mounting system until flames have reached the 'ceiling' formed by the canopy.
(b) If a plastic fixing system this may give way well away from the flames as the hot but non-flaming part of the plume spreads underneath the canopy - this may lead to collapse of intact netting hindering escape at some distance from the fire.
(c) If of the same natural materials as you think the netting is made of, this will probably hold up until the temperature gets quite high (ie at the auto-ignition point) or actual flames impinge upon it. The netting will still be released, but probably over a much smaller area in the vicinity of the fire. So this hopefully will be less of an escape hazard.
Hope these thoughts may be of use.

[Ken Taylor]

Ant-bird net tends to be a propietary product bought in and installed by a specialist company - usually fixed by metal hooks to enable release for access to buildings for maintenance, etc. In the circumstances described, I would expect the risk assessor to have obtained a specification (including flammability, etc) from the manufacturers of the net.

[Chris Houston]

New netting might have different properties from dirty old netting.  Old netting may have a lot of dirt and dust in/on it.