A Microsimulation-Based Analysis of the Price of Anarchy in Transportation Networks during an Evacuation

To find optimal routes, many drivers use navigation systems, especially during congested times. This study analyzed traffic patterns during a no-notice evacuation event based on two different scenarios, socially optimal routing (following the primary evacuation routes) and selfish routing (drivers using guidance from navigation systems). The chosen road network was ideal for this study because there existed multiple paths with differing capacities. This study was the first known analysis of the price of anarchy (PoA) during an evacuation event. The PoA was quantified as the difference between socially optimal route scenarios and selfish routing scenarios, utilizing the costs of delay and vehicle emissions. The findings show that the PoA for an evacuation can vary between 1.01 and 1.07, during the timespan of an evacuation. As expected, the network with socially optimal routing was found to have less traffic congestion compared to the network with selfish routing. In addition, the selfish routing scenarios had significantly higher variation in both travel time and delay time. These findings suggest that navigation systems may cause unintended delays and variability during an evacuation. Future research could evaluate different demand profiles, road networks, and/or intersection operation schemes.