Methodology for Determining Vulnerable Links in a Transportation Network

Abstract

A bilevel formulation is developed to identify vulnerable transportation network links. The problem can be viewed as a game between an "evil entity" and the traffic management agency. At the lower level, the traffic management agency routes vehicles according to the system of optimal traffic assignment. At the upper level, the evil entity seeks to maximize disruption to the network. A key component of this formulation is the vulnerability index, which is a measure of the importance of a specific link to the connectivity of an origin-destination pair. The vulnerability index accounts for the availability of alternate paths, excess capacity, and travel time. The vulnerability indices are aggregated across all origin-destination pairs into the disruption index. This disruption index is the measure of damage to the network by which the evil entity might rank links as targets. Because the evil entity has a limited amount of resources, it cannot strike all of the potential targets and must choose among subsets of links. Four cases with different types of information availability for the evil entity and the traffic management agency are examined for a simple network. In each case, the evil entity is assumed to aim its strike at the link that has the potential to carry traffic for the most origin-destination pairs.