ALARP and cost-benefit of safety measures for the evacuation concept of along Norwegian railway tunnel

摘要

The evacuation concept of the new 5.5 km single-bore double-track tunnel was proposedrnsimilar to some tunnels constructed a few years ago, based on fans that should create one smoke-freernside in potential fires. However, as the current tunnel was different from the previous ones, a set ofrnCFD simulations were carried out in order to gain confidence in the proposed concept.rnThe CFD simulations revealed that the proposed fans would not be able to create a wind-field strongrnenough to guarantee a smoke-free side in all locations of the tunnel, due to the tunnel's low-point, thernmain particularity compared to the uniform-sloped previous tunnels.rnIt was decided to carry out a full-fledged risk analysis of the potential of a train-fire in the tunnel, itsrnconsequences and potential needs for implementing risk reducing measures according to the riskrnacceptance criteria based on the ALARP principle.rnAlthough the event of a train with fire forced to stop in the tunnel was estimated to a very lowrnprobability, the acceptance criteria and the multiple-fatality potential of such an event provided for thernhigh disproportion factor of 10 for measures that could reduce risk.rnNo measure involving an evacuation tunnel was found worthwhile in this regard, only measuresrnconcerning forced ventilation and segmentation of the catenaries passed the ALARP criterion.