The generation and alleviation of air pressure transients caused by the high speed passage of vehicles through tunnels.

The possibility of designing a railway tunnel to minimize the air pressure transients which are generated during the entry of a high speed train are investigated. In particular, considerable emphasis is placed on reducing the magnitude and/or the rate of growth of the primary pressure wave which results when the air is first accelerated from rest. Equations of motion for unsteady, compressible flow in a one-dimensional duct are introduced and expressed in characteristic form.