RAIL TUNNEL RISK ANALYSIS - A tool to improve rail tunnel design

A methodology to conduct an extended risk analysis in accordance with Italian law was applied to evaluate the effects of rail tunnel characteristics on the likelihood of passenger survival in case of a fire. The procedure allows one to calculate the heat and toxic gasses concentrations inside a tunnel due to a fire of different characteristics (in terms of heat release rate and heat release development time) and to calculate their diffusion and their effects on passengers. The likelihood of saving people and the number of expected deaths as a function of the distances covered by each passenger have been obtained from the application of the methodology. The variables considered in the performed study included the fire event characteristics, the number of available safety walkways in the tunnel, the train offered capacity, and the escape capabilities of people (consciousness and reaction times and evacuation procedures). The applied methodology has been proven highly useful as a design tool to identify the best design, construction, and management options to increase safety levels.