Some Design Considerations of a Fire Within a Sub-surface Railway Switches and Crossings

Abstract

This study was performed to assess the event of a fire on a train within the S&C area, addressing the limiting of smoke flowing into either the adjacent station or the tunnels. Both areas of infrastructure had to be protected as they could be occupied by people either at the station or in trains, as well as being potentially part of the evacuation route for occupants of the S&C area. By the very nature of the S&C, the evacuation of passengers within this area also posed an issue due to the routes to safety, which are not easily protected in such a relative large enclosed space. The access routes for fire brigade and the firefighting environment were also considered. The following briefly outlines the application of two fire engineering toolbox techniques; CFD smoke modelling and evacuation analysis. These tools provide important components required to perform an ASET and RSET assessment, which can provide powerful insight into the ability of passengers to escape. By constructing a 3D CFD model and measuring key parameters with respect to time, the tenability along the potential escape routes was considered. Combining this data with a travel time assessment of the evacuating passengers informed the performance-based approach to develop an optimum and specific ventilation and evacuation strategy. These in turn allow for guidance to be developed on the training and management requirements, which are to form part of the overall system’s operational emergency procedures. It also addressed the considerations for the access provisions for the fire brigade.