Abstract
When high-speed trains are running and passing each other in a tunnel, these generate compression waves ahead of trains. These waves are propagated through the tunnel and causes a large pressure transients are generated against trains. It is necessary to predict these pressure transients accurately in planning speed-up of Shinkansen trains. From this point of view, it is important to clarify the formation mechanism of pressure transients and the waveform of the pressure wave generated by the trains passing each other in a tunnel. In this paper, pressure transients are calculated by characteristic method in the high-speed train/tunnel systems and the formation mechanism of pressure transients is clarified.