Abstract
The present paper indicates that effects of smoke extraction by ventilation system in road tunnel fires, which model tunnels adopted urban U-shaped tunnels shorter than 500 m length. The investigation used smoke CFD simulation and evacuation simulation. In the case with natural ventilation velocity 1.2 m/s, the situation where it difficult for over 10 users to evacuate due to exposure by smoke occurred with no smoke extraction by ventilation facilities. Meanwhile in the case with over 0.3 m3/s·m of smoke extraction by ventilation facilities, smoke propagation can be controlled even with natural ventilation existing, the number of users exposed by smoke decreased from 3 persons to 0. Hence, it was confirmed that even in short tunnels smoke extraction by ventilation facilities was necessary to keep the users' evacuation safety in tunnel fires.
