Ken I think you need to specify what sort of tunnel you are talking about. Design criteria would need to take into account the expected population at risk in normal and eg. emergency scenarios. P

There was a similar thread recently - may be of use: http://forum.iosh.co.uk/...aspx?g=posts&t=97342

Ken, a useful document for this is the FLAs Green Guide - see Section 10 and the worked examples at the back. http://webarchive.nation...afetyatSportsGrounds.pdf You have 2 pinchpoints that will cause backlogs - at the point the tunnel narrows where the lift is and at the final exit point. Also, you'll have wheelchair users and semi-ambulent pedestrians joining the crowd flow from the lift which will slow things down as well (assuming they exit it into the tunnel - If they use it to access another exit and are standing around waiting for it to arrive while this tunnel is in use it's going to cause a lot of problems). I would work out an exit capacity from this tunnel using the narrowest point. You can either use the old estimates for crowd flow (4th ed of the Guide assumming it's not new build) or the new estimates (5th ed) - Using the old calcs you get 2.6 x 109 = 283.4 people/min and using the new figures for recommended flow rates you get 2.6 x 82 = 213.2 people /minute. If you use any wider figure for the tunnel as you suggest then you'll still get a backlog when they reach the narrowest point anyway. You'll also create 2 reservoir areas (before the lift where it narrows and at the point of exit) and you'll need to make sure these can accommodate the numbers linkely to be coming into the area before they can get out - 40 persons per 10 sq m is the density allowed. If you're having problems with more than this trying to get into the tunnel in the first place then you need to come up with strategies to divert them away from it and towards other exit routes providing you have them and they are able to accommodate the extra capacity. This could include stopping use of this tunnel as a means of access to your main area (people like to go out the way they've come in so if they don't come in this way they're less likely to want to use it to get out). Also signage, information and stewarding also spring to mind as possible ways to do this. Hope this helps