Numerical methods in the prediction of pressure fluctuations on board trains passing through tunnels

As a train enters or leaves a tunnel, pressure waves are generated that travel up and down the tunnel at sonic speed. Due to the superposition of the waves, passengers experience complex pressure fluctuations that can cause aural discomfort. Sizing the tunnel appropriately or pressure sealing the train are two possible methods to ensure a satisfactory level of passenger aural comfort. A one-dimensional numerical model, based on the method of characteristics for the prediction of tunnel pressures, is described. A finite difference model that gives accurate predictions of the internal pressure fluctuations on board sealed trains is explained.