California Partners for Advanced Transportation Technology

This report models response times and delays for highway incidents, according for spacing between interchanges and the time penalty for changing directions, enabling a response vehicle to reach an incident on the opposite side of the highway. A fundamental question in dispatching incident crews is whether to send the closest vehicle that is currently available or to wait for another to become available that is even closer. Waiting for a closer one is advantageous because service time is effectively reduced, adding to capacity and providing stability at higher levels of utilization. But waiting for a vehicle to become available adds uncertainty, which contributes to expected traffic delay. As a consequence, any reasonably robust dispatch strategy must provide for a hybridization of the two objectives, trading off greater certainty in response time against stability at higher utilization levels.