Emergency fire evacuation simulation of underground commercial street

High-density built-up areas in cities often enlist the underground realm to provide solution space for transport, shopping and other purposes. The special location, layout, and accessibility of underground structures often generate unique and acute safety-risk concerns. They are inadequately understood and managed and cannot be tackled appropriately by conventional risk assessment and abatement methods. This study focused on evacuating underground commercial streets (UCS) with a heavy concentration of people in Fuzhou city in China. Despite the widespread use of building information modeling (BIM) in construction, it has rarely been applied to studies of underground shopping streets. This study adopted BIM technology as the core method, in conjunction with PyroSim fire and Pathfinder evacuation simulation software. Different fire scenarios in four fire protection zones and the most unfavorable fire sources were set in the model. Based on a calculated number of persons at the start of a fire, different movement paths, stair configuration and exit width were simulated. The choice of escape routes, congestion locations, and slack time windows were identified by the graphical images of the simulation programs. Required safe egress time was compared with available safe egress time, and the number of successful evacuees was reckoned. The effects of three escape-stair forms on evacuee utilization and evacuation rates were evaluated. Their evacuation efficiency was ranked: crossed stair > straight stair > parallel-double stair. The simulation results can optimize building layout design and improve understanding of evacuation-efficiency factors. The findings can contribute to reducing casualties and property losses and improving UCS's fire safety management.