Full scale fire experiments in a tunnel

Two pilot fire experiments were carried out in a tunnel 140 m long, 6 m wide and 5 m high. The tunnel had unprotected surfaces of natural calcite rock. The first experiment was designed to simulate fire in a subway car. The second experiment simulated fire in a queue of cars. Forced ventilation of 7 cu m/s was used. Fire load was made of wood cribs. In the first experiment the distributed fire load burned with a constant velocity of 0.7 mm/s without flashover. In the second experiment two piles of 500 kg wood burning with a power of 8 mw did not ignite a third pile 1.6 m apart. The spalling of rock off the ceiling and walls was very strong.