In June 2011 a train set of 8 wagons and a 50 years old avalanche cover constructed of woodwere destroyed in a fire on the Norwegian railway. The fire was investigated by the AccidentInvestigation Board Norway (AIBN). This paper describes SINTEF NBL's contribution to this officialinvestigation. Our mandate was to assist in the investigation of the fire cause, and in particular toexplore the possibility that hot particles from thermite welding and grinding of rails may have causedthe fire. The assessments were supported by a literature review, and by fire testing in a realisticenvironment as well as laboratory small-scale fire testing. Materials similar to the wood in thedestroyed avalanche cover were used in the tests. The wood material was not ignited in any of the realscale tests in connection with thermite welding. Because of practical reasons only a very limitednumber of tests were run, and optimal conditions for ignition were obviously not obtained. The smallscale tests showed that the aged wood material had an ignitability in the same range as fresh wood, andindicated that hot particles may initiate a combustion process in the material. Although no clearconclusions on the actual fire cause could be drawn from the tests, they gave good insight to thepossible fire hazards connected to thermite welding and grinding of railway tracks.
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