On the use of agent-based modeling approach for studying tunnel egress in mass transit system

The mass transit system in Hong Kong carries over 3.7 million passengers everyday. With the rapid development of the community, its network has been extended over the years. New lines in the territory and connection to the Mainland are constructed. While the system is carrying huge volume of passengers per day, the safety of passengers in case of fire and emergency is one of the major concerns of the mass transit company as well as the government. The operator has endeavored to avoid accidents to happen in the system, yet zero risk situation cannot be guaranteed. To mitigate the ill-effect of an accident, provision of an efficient egress system is necessary. The design of fire and emergency egress system usually refers to the Guidelines prescribed by NFPA130 - Fixed Guideway Transit and Passenger Rail Systems for tunnel emergency egress provisions. The 2010 edition of the standard denotes that "emergency exits shall be provided from tunnels to a point of safety" and that "within underground or enclosed trainways, the maximum distance between exits shall not exceed 762 m. In view of the complex urban topography and existing building configurations, the orientation and design of tunnels for the subway system can be restrictive and the prescriptive guidance in NFPA130 can sometimes hardly be met and performance evaluation may sometimes be required in order to obtain the approval from relevant government authorities. Fire safety strategies are established for the design and operation of each line. However, the performance of the strategies, in view of the complexity of the system, may not be objectively evaluated in all aspects. The aim of this proposal is to develop an agent-based egress model to explore the evacuation pattern of evacuees in rail tunnels and associated facilities. The simulation results can be adopted to evaluate the effectiveness of different tunnel egress design and assist the establishment of trackside emergency egress strategies. It can also provide insight for the design of smoke extraction and formulating appropriate means of access for firefighting and recue strategies.