Escape through beer garden

[lyledunn]

I was at a site meeting today with client, architect and building control. It concerned the discharge of escapees from a niteclub and an adjoining hotel through a proposed beer garden. Both premises are separated but will share the beer garden which will be enclosed on all sides by perimeter walls. Emergency exits from both premises currently discharge in to part of a car park where people can take almost any direction to safety. The intention is to construct a beer garden such that people escaping from both premises will now be routed along a defined passage which is approximately 2m wide and bounded on both sides by walls about 1.2m high. There are alternative MOE from the beer garden but nothing would stop the defined route being used by any one using the beer garden. Numbers from the niteclub could be +500 and something similar from the hotel.
Now I assume that the width of the route would only need to cater for one of the premises as they are both adequately separated?   Even so, the BC guy agreed to the 2m width even though it could be required by 500 people. He may have been content that escape could also be made through the beer garden to the escape doors in the perimeter walls although this would mean diverging from the defined route.

[Davo]

Hi Lyle

Signage & EL?
Car Park again.........

davo

[JT]

Nightclub moe linking with hotel moe shouldn't be a problem as you say they are fully separated.
Could the sounders cause confusion between premises?

How many moe do you have and what's the widths? Length of your proposed route may come into it - flow rate of people.
Building control will sign off jobs as long as you don't make the building worse. Then a fire safety officer may arrive and restrict your nightclub to 400 people.

[kurnal]

Sounds ok to me provided legalities and rights of way are in place. It is fine to assume only one building will have a fire at any time but you might consider external sounders / strobes to on each building to discourage  persons using the beer garden from entering the building if the alarm is sounding, though marshalls could also carry out this role.

Point on the 2000mm is that persons are in a place of relatve safety once outside and  conventional escape times for buildings do not apply once they are in the beer garden. And at 2000mm they are not far out in any case - without calculating it its probably around 3 mins which is a respectable time for existing buildings of limited combustibility. Once outside consider lighting, the premises may or may not be open at the same time. 

[Dinnertime Dave]

Sounds ok to me provided legalities and rights of way are in place. It is fine to assume only one building will have a fire at any time but you might consider external sounders / strobes to on each building to discourage  persons using the beer garden from entering the building if the alarm is sounding, though marshalls could also carry out this role.

Point on the 2000mm is that persons are in a place of relatve safety once outside and  conventional escape times for buildings do not apply once they are in the beer garden. And at 2000mm they are not far out in any case - without calculating it its probably around 3 mins which is a respectable time for existing buildings of limited combustibility. Once outside consider lighting, the premises may or may not be open at the same time. 

I agree that they are in a place of relative safety, assuming the beer garden is a decent size. The outdoor event guide may give some direction, I would suggest it a starting point, I've not checked but this varies between 70 & 110 persons per m per minute. I would suggest treat it as high risk due to presence of alcohol and darkness, the guides reduce time not people per minute. If you use kurnal's 3 mins and 100 persons per metre per minute, we get 600. Oh and will the beer garden have people in as well. If it does you need to add them in as well.

[kurnal]

From the OP I think we are looking at +500 persons Dave. ADB would suggest an exit of 2000mm wide would pass 160 persons per minute so my notional evacuation time of 3 minutes would pass 480 persons. But if as you say the garden is big enough they are in a place of safety and the bigger it is the safer. If for example persons can assemble further than 1.5 times the building height they should be in a place of complete safety and time becomes irrelevant.

Sorry for banging on a lot today been on the chemo and had nothing else to do, and now the steroids are keeping  me awake! Still at least I take consolation knowing I am sending the rest of you to sleep with my drivel.

[Dinnertime Dave]

From the OP I think we are looking at +500 persons Dave. ADB would suggest an exit of 2000mm wide would pass 160 persons per minute so my notional evacuation time of 3 minutes would pass 480 persons. But if as you say the garden is big enough they are in a place of safety and the bigger it is the safer. If for example persons can assemble further than 1.5 times the building height they should be in a place of complete safety and time becomes irrelevant.

Sorry for banging on a lot today been on the chemo and had nothing else to do, and now the steroids are keeping  me awake! Still at least I take consolation knowing I am sending the rest of you to sleep with my drivel.

Did a couple of courses at the Emergency Planning College on sports grounds and mass gathering, they suggested the 140p/m/m is a dangerous figure they had tried to do it. These numbers cause people to trip and fall.

Get well soon, hope everything is going ok.

[lyledunn]

Kurnal, "drivel" is not a word that I would associate with you in any way! I have the utmost respect for your replies. When I post and see that Kurnal has responded I know that I am getting an opinion from a man at the top of his profession. For that I am very grateful, you have no idea how helpful this forum is to my own job. For that I would like to thank you and all the rest of the guys who are kind enough to indulge me.
I am sorry to learn of your illness and I wish you strength and fortitude to see your way through it.

[kurnal]

Dave the 140 persons per minute is for the stated 2m wide exits out from the garden, this is derived from ADB and is the flow rate calculation used as the benchmark in both ADB and BS9999 of allowing 5mm per person for exits wider than 1000mm?

Working it through ,the  ADB states that for exits wider than 1000mm allow 5mm/person. This figure assumes astandard building with a 2.5minute exit time . 400 persons @ 5mm per person requires 2000mm wide exits and this equates to a flow rate of 80 persons per minute per metre of exit width. I have quoted 160 persons per minute as the exit is 2000mm wide

. I am assuming that we are only considering that part of the exit route that passes through the garden is under consideration, that only one exit is being considered and that other exits from the building are not in question. I also assume - taking your point well made that most people are in the building and the garden simply forms part of the exit route for the majority of  people.

So if the 2000 mm wide exit has a capacity of 400 persons over  a timescale of 2.5 minutes this equates to a flow rate of 160 persons per minute and if the time is extended to 3 minutes 400 x 3/2.5= 480 persons. The flow rate is unchanged - only the time allowed has been increased and I think without seeing the place that probably 3 minutes from an outside location is probably unreasonably  stringent taking into account most large sports venues and outdoor events where 7.5 - 15 minutes are typical.

[Mike Buckley]

I would agree with kurnal once the people are outside the building they should be in a place of safety. The only issue that would arise is people being able to leave the beer garden. Personnally I would not be too concerned about the rate of exit from the beer garden, as I would see the beer garden acting as a type of holding area and not as a passageway, rather like a flood plain next to a river.

[col10]

It would concern me that the route is for up to 500 night club occupants, inebriated, wearing inappropriate footwear.

I would want to check that it didn't bottle neck back into the building and that the holding area wasn't threatened by fire from the building.  The route needs to be cleared of snow and ice.

[JT]

What are the other exit widths?
It's all very good having 2m but you may have to write that off and go with your 750mm exit or whatever you have.

[Dinnertime Dave]

Dave the 140 persons per minute is for the stated 2m wide exits out from the garden, this is derived from ADB and is the flow rate calculation used as the benchmark in both ADB and BS9999 of allowing 5mm per person for exits wider than 1000mm?

Working it through ,the  ADB states that for exits wider than 1000mm allow 5mm/person. This figure assumes astandard building with a 2.5minute exit time . 400 persons @ 5mm per person requires 2000mm wide exits and this equates to a flow rate of 80 persons per minute per metre of exit width. I have quoted 160 persons per minute as the exit is 2000mm wide

. I am assuming that we are only considering that part of the exit route that passes through the garden is under consideration, that only one exit is being considered and that other exits from the building are not in question. I also assume - taking your point well made that most people are in the building and the garden simply forms part of the exit route for the majority of  people.

So if the 2000 mm wide exit has a capacity of 400 persons over  a timescale of 2.5 minutes this equates to a flow rate of 160 persons per minute and if the time is extended to 3 minutes 400 x 3/2.5= 480 persons. The flow rate is unchanged - only the time allowed has been increased and I think without seeing the place that probably 3 minutes from an outside location is probably unreasonably  stringent taking into account most large sports venues and outdoor events where 7.5 - 15 minutes are typical.

I am not arguing whether it is correct in print. My point is that test done by the consultants and a number of football organisations indicated that it was difficult to achieve safely. Add alcohol and unfixed pub garden furniture to the mix then it may be more difficult.

9999 allows people to move to another compartment, then evacuate (a well known supermarket does it) so why not a beer garden.

[lyledunn]

I use the term beer garden, but this is a student area and there is every possibility that the beer garden would be crammed, perhaps with spillage in to the escape route. So unless something stirs the crowd in the beer garden in to moving then we could have a bit of a log jam if the niteclub required to be evacuated, much as Colin Cox has pointed out.

[Davo]

lyle

will the tables/benches/chairs be fixed to maintain the exit width?

davo