PURPOSE: To prevent a 'tunnel dong' phenomenon and reduce the construction cost by generating air currents nearly perpendicular to the advance direction of a moving object over the whole cross section face of a tunnel with a facility provided near the outlet of the tunnel.

CONSTITUTION: When railroad vehicles 4a, 4b approach a tunnel 1, a sensor detects them and sends a vehicle detection signal 16 to the drive source of a pipe 11 via a wire 15. The air outside the tunnel 1 is fed to a chamber 5 via a pipe 11 by the drive of the pump 12 to increase its pressure. The air in the chamber 5 is fed into the tunnel 1 via vent holes 2, and air currents flowing in the direction nearly perpendicular to the advance direction of the railroad vehicles 4a, 4b in the tunnel 1 are generated over the whole cross section face of the tunnel 1. Compression waves generated at the front of the railroad vehicles 4a, 4b are propagated at the sonic velocity in the tunnel 1, and a 'tunnel dong' phenomenon caused when part of them is quickly discharged at the outlet of the tunnel 1 is prevented.