ABSTRACT
An increasing number of transit authorities are pursuing a transition of their entire bus fleets to zero-emissions technology, specifically battery electric buses, to decarbonize the transportation system. This continuous shift to battery powered buses is associated with new hazards, including fires containing lithium-ion batteries undergoing thermal runaway reactions. This study focuses on identifying any key fire-life safety issues associated with a battery electric bus fire in an underground infrastructure. A design fire heat release rate curve for a battery electric bus is developed and fire scenarios in a roadway tunnel are modeled with occupants egressing. The analysis accounts for the severity of the structural impact from the thermal exposure on the tunnel. Results are compared with a conventional internal combustion engine bus fire scenario which would provide insight into fundamental questions including whether battery electric bus fires cause conditions in a tunnel to be more harmful.
