Experimental study on thermal and smoke control using transverse ventilation in a sloping urban traffic link tunnel fire

A set of full-scale experiments was conducted to study thermal and smoke control strategies using transverse ventilation system in a sloping urban traffic link tunnel (UTLT). Results showed that it is not the case that the slower the smoke spread longitudinally, the better the smoke being controlled. For transverse ventilation, within the smoke extraction compartment, the faster the smoke spread to the exhaust vents the faster the smoke being extracted from the tunnel. More importantly, the operation of the exhaust and supply vents for transverse ventilation in real time should take the effect of tunnel slope into consideration. For tunnel with a slope going uphill from upstream to downstream, supplying air from the downstream is recommended while supplying air from the upstream or directly to the fire located smoke compartment should be avoided. Additionally, for a given total smoke exhaust volume flow rate, increasing the number of exhaust vents is an effective way of controlling the smoke layer interface height. For the kind of tunnel as studied at hand, open the exhaust vents in the fire located compartment and its downstream smoke compartment is recommended.