Challenge

Like many states on the East Coast, North Carolina faces the threat of hurricanes during the summer months. The current evacuation strategy for the state is a full reversal of I-40, allowing all lanes to travel away from the coast. Although this strategy has never been activated, the North Carolina Department of Transportation (NCDOT) recognized that there could be situations in which it may not work. NCDOT hired Kittelson to create a “playbook” that will allow the State to have multiple evacuation strategies at hand and to understand the conditions that would mandate each strategy to be implemented.  

Solution

Typically, evacuation studies learn demand by focusing on the number of people who evacuate over a period of time. However, for this study, Kittelson looked at different capacity scenarios by modifying Freeval, a powerful analysis tool used to look at capacity and monitor signalized intersections over multiple days. The team also took existing tools and strategies from NCDOT and adapted them into Freeval to get a better understanding of capacity, speeds, and travel time. This allowed the team to see what could happen during each evacuation strategy and how that strategy might affect traffic. Kittelson met with all NCDOT divisions and Cities along the coast to hear directly about their experiences from past evacuations to inform the process further.  

The photo above shows a list of strategies evaluated in the evacuation toolbox for NCDOT, ranging from signal retiming to interchange improvements, to the full reversal of all travel lanes to support evacuation traffic.