A Survey on Emergency Vehicle Preemption Methods Based on Routing and Scheduling

Emergency Vehicles (EVs) play a significant role in saving human lives and property damages. Reducing the time delay of emergency vehicles is important to enhance emergency service performance. The preemption methods are powerful strategies that assist emergency vehicles to reach the desired destination quickly by managing the competing normal traffic along the emergency vehicle approaching lane. The EV preemption models pre-clears the vehicles on the EV approaching lane by interrupting the signal timings and boosting EV arrival speed even the road traffic is high. With the assistance of preemption models, the EVs are not stopping or waiting at signalized intersections. Also, the preemption models diminish the vehicle conflict problems on the EV approaching lane. Moreover, the preemption models use different strategies to navigate the EVs on their routes efficiently. Hence, a detailed survey is needed to understand the different preemption strategies and analyze the gaps which are not effectively solved by existing literature. This paper attempts to survey the existing EV preemption methods with detailed discussions. For a clear view, the survey divides the existing preemption models into three types that are routing-based, scheduling-based, and miscellaneous. The survey compares the preemption methods with their advantages and limitations. Further, it analyzes the gaps which are not solved in existing solutions and describe the possible future directions that pave the way for innovating novel realistic preemption solutions.