Coupling Risk Assessment Framework of Interdependent Urban Lifeline System

The urban lifeline system is a complex and fragile network containing multiple interdependent subsystems, like transportation, gas, and electricity. A dynamic and quantitative model for coupling risks that balances accuracy and efficiency is both a theoretical and practical challenge. Regarding the accident evolution and control optimization of multiple lifeline systems, a systematic QRA framework comprising risk identification, risk analysis, and risk control optimization is proposed by taking energy out of control as the primary units of incidents. Multidimensional energy out of control is quantified by analytical and graph-based methods. Based on the emerging modelling framework, the proposed framework enables dynamic simulation of cascading failures caused by various internal and external events in lifeline systems. In the case of an LPG tank truck leakage, the spatial and temporal evolution of coupling risks in a transportation-gas-electricity system is quantified and verified, including chemical leak, explosion, power outage, gas outage, and road disruption. The critical points from spatial and functional perspectives in the lifeline system are identified and corresponding risk control suggestions for different urban areas are proposed to achieve detailed risk decoupling in the giant urban lifeline system, considering physical mechanisms. Moreover, the dominant effect of function dependency and amplification effect of spatial adjacency of coupling events in the urban lifeline system are identified.

Keywords: QRA, urban lifeline system, coupling risk, energy out of control, power grid.