Actuated Signal Timing Optimization for a No-Notice Evacuation with High Left-Turn Demands

The determination of the appropriate traffic signal timing plans for no-notice evacuations in densely populated areas is a noteworthy challenge. The objective of this study was to evaluate alternatives that could optimize evacuee traffic flow in a no-notice evacuation of areas near an oil refinery. This simulation case study focused on a residential area in the City of Wood River, Illinois, and used Synchro 8.0 and VISSIM 7.0. This case study was different from existing evacuation literature because of the high left-turn demand from evacuating traffic. The study methods were unique because of the application of dynamic traffic assignment, a left-turn movement on the evacuation route, and the simulation of fully-actuated traffic signals. These scenarios evaluated the following: (1) existing traffic infrastructure; (2) flexible shelter choice; and (3) optimized traffic signal timing with flexible shelter choice. The results suggested that optimizing the signal timing and allowing drivers’ flexibility in choosing evacuation routes achieved the fastest evacuation. These findings indicated that a longer cycle length and an extended left-turn phase were important factors in reducing traffic delay in the network. Overall, these findings underscore the importance of operating intersections efficiently during no-notice evacuations.