Perspectives for Network Management in Response to Unplanned Disruptions

This paper presents two important perspectives that road authorities should consider under terrorism evacuation scenarios. First, households have been observed to gather prior to evacuating an area. Rather than immediately evacuate these drivers delay or even head into danger to collect household members. This gathering phenomenon leads drivers to follow previously unanticipated activity chains, which result in extensive evacuation times and atypical traffic patterns. These traffic patterns should be considered in conjunction with terrorists’ targeting strategies, which represent the second perspective. In this paper, the targeting strategies are assumed to be based on maximizing disruption to transportation network connectivity. This work considers a postimpact emergency evacuation, presents a mathematical model of how households may react to the evacuation conditions, and describes how a terrorist may select links to damage. If the terrorists’ intent is to cause disruption, the links that are most important to completing an evacuation successfully become the most likely targets. However, at any given time, in a well connected network, the most important links are not necessarily the ones leading out of the evacuation area, as shown through a simulated case study.