Fire safety of polymer sleepers in terms of fire propagation

This article deals with the fire safety test of polymer sleepers in the ballasted track. Although the occurrence of a fire in the track is unlikely, it may occur, for example as a consequence rolling stock fire or arson. In the past, old rolling stock assembly or track maintenance could lead to fire. For these reasons, products installed in track must be fire-safe. A new trend in the sleeper development is the utilization of polymer-based materials that suitably combine the beneficial properties of prestressed concrete and impregnated wood. In the recent developmental phase, polymer sleepers have been subjected to laboratory testing in which their mechanical resistance has been successfully verified. Nowadays, the polymer sleepers must be tested in their authentic environment and within train operations. This paper deals with an in situ fire test of chosen polyethylene sleepers, in which a fire in track was intentionally initiated. The aim of the test was to verify the possibility of spreading fire between sleepers in conditions of their application. Conclusions from the fire test are based on monitoring the temperature development by infrared thermography, thermocouples, visual inspecting fire spread, and wind direction and velocity monitoring by an anemometer. Justified by temperature monitoring no significant heat transfer between polymer sleepers was observed during the test. Therefore, the assumption about the insulation-like property of crushed stone was confirmed and the fire safety of polymer sleepers subjected to the fire propagation test between sleepers was demonstrated.