Simulation-Based Stress Tests: Integrated Simulation Approach for Assessing Resilience of Transport Systems under Multiple Stressors

A transportation system stress test is a set of one or more hypothetical scenarios designed to help determine if a transport system can continue to provide an acceptable level of service when subjected to one or more potentially disruptive events. Stress tests, if done well, enable policy makers, regulators, and network operators to assess the ability of transport systems to withstand and recover from potentially disruptive events, and modify the systems if necessary. Although work has been conducted on how to conduct high-level preliminary transportation stress tests, there has not yet been work conducted on how to conduct detailed quantitative simulation-based stress tests on transportation systems. This paper fills this gap by presenting both an approach to conduct simulation-based stress tests and example simulation-based stress tests for a transportation system subject to potentially disruptive hydrometeorological events. Three types of stress tests are conducted for the transportation system in the region of Chur, Switzerland, which is subject to heavy rainfalls that may result in floods and landslides. These include the stress caused by climate change leading to increasing the intensity of extreme rainfall events in the future, stress caused by uncertain future mobility behavior of people leading to excessive travel demand on the network, and stress caused by poor planning of the required resources for restoration interventions leading to having less resources for restoration than planned. It is argued that conducting such stress tests makes it clear to decision makers whether or not a transportation system is sufficiently resilient against various stressors, and if not, gives clear indications as to how it could be improved.