Vulnerability Assessment Methodology for Swiss Road Network

This paper presents a methodology that incorporates vulnerability to natural hazards into current infrastructure management systems. The paper is mainly concerned with presenting the methodology applied to assess the transport-related consequences of link failures, including congestion effects on a networkwide scale. Four possible demand shifts caused by single link failures can be expected: detours, shifts in mode choice, shifts in destination choice, and trip-activity suppression. The paper demonstrates that detours are by far the predominant demand reaction. Hence, the quantification of detour-based principal consequences is the main focus. The main challenge was to overcome the calculation time intensity of this equilibrium-based approach. Since demand shift effects were assumed to be spatially restricted around the failed link, subnetworks were used, that is, limited sections of the complete network that were cut out, including their internal and transit demands. The resulting failures turned out to be consistent with those that involved the full network, even for links with long path distances or long detours. On the basis of computed consequences of link failures and on link parameters, a statistical model was developed to reveal and quantify the main factors defining transport-related consequences. Furthermore, the findings highlight potential gains, including rail networks, mode shifts, and destination choice shifts in network vulnerability assessments.