When Shinkansen train runs into a tunnel, big sound and
vibration occur at the exit side of the tunnel.
It is generated
by a pressure wave originated from the entry of the train into
the tunnel. We calculate the pressure change at the instant of
the tunnel entry.
Higher pressure region becomes large when the train runs into
the tunnel. This pressure wave generates the big noise.
The pressure change becomes larger as the train runs faster. It
is important to make the pressure change smaller when designing
the leading nose shape of Shinkansen.