Two-Level Routing Framework to Facilitate the Movement of Emergency Response Vehicles in a Transportation Network

This paper introduces a two-level routing (TLR) framework to evaluate a system facilitating the movement of emergency response vehicles (ERVs) through a transportation network. This facilitation system utilizes a mixed-integer programming (MIP) model to generate a clear path for multiple ERVs in a transportation network while addressing the continuous movement of vehicles. This model uses information from non-ERVs, such as locations and speeds, and help them to stop in a specified position before ERVs arrive. The transportation network consists of multiple transportation links addressed sequentially using the simulation. Different proposed situations may allow ERVs to utilize a virtual emergency lane (VEL) (an additional lane created by narrowing the existing lanes and utilizing extra space from hard shoulders), contraflow lane, or median lane, depending on traffic congestion and road type. A dynamic routing approach is applied to help ERVs choose the shortest travel-time path throughout the network. The traffic simulation tool SUMO executes Dijkstra’s algorithm integrated with optimization results in this dynamic routing approach. Several cases encompassing different ERV types, origins, destinations, and the presence/absence of traffic signal preemption have been designed to evaluate the proposed framework’s performance. Results demonstrate that the proposed framework outperforms static routing, with or without optimization, in improving ERVs’ travel time, where the upper ranges of improvement mostly occur when more links exist between origins and destinations, the locations of origins and destinations allow access to more alternative routes, and ERVs can use more contraflow lanes, VELs, or median lanes, compared with the lower ranges of improvement.