Abstract
Emergency vehicles (EVs) play a crucial role in providing timely help for the general public in saving lives and avoiding property loss. However, very few efforts have been made for EV prioritization on normal road segments, such as the road section between intersections or highways between ramps. In this paper, we propose an EV lane pre-clearing strategy to prioritize EVs on such roads through cooperative driving with surrounding connected vehicles (CVs). The cooperative driving problem is formulated as a mixed-integer nonlinear programming (MINP) problem aiming at (i) guaranteeing the desired speed of EVs, and (ii) minimizing the disturbances on CVs. To tackle this NP-hard MINP problem, we formulate the model in a bi-level optimization manner to address these two objectives, respectively. In the lower-level problem, CVs in front of the emergency vehicle will be divided into several blocks. For each block, we developed an EV sorting algorithm to design optimal merging trajectories for CVs. With resultant sorting trajectories, a constrained optimization problem is solved in the upper-level to determine the initiation time/distance to conduct the sorting trajectories. Case studies show that with the proposed algorithm, emergency vehicles are able to drive at a desired speed while minimizing disturbances on normal traffic flows. We further reveal a linear relationship between the optimal solution and road density, which could help to improve EV routing decision makings when high-resolution data is not available.
Highlights
Emergency vehicles (EVs), such as fire trucks and ambulances, are essential components in modern Emergency Medical Service (EMS) systems
The present paper focuses on the problem of EV prioritization at highway segments, which are defined as extended sections between intersections or ramps on freeways or urban roads in this research
We propose a cooperative control strategy for local EV priority at highway segments
Summary
Emergency vehicles (EVs), such as fire trucks and ambulances, are essential components in modern Emergency Medical Service (EMS) systems. Note that in the present paper, we assume that all drivers would comply with such trajectories and prioritize EVs based on emergency protocols To this end, in this study, we propose a cooperative control strategy for EV prioritization at highway segments in connected environments. This work contributes to the state-of-the-art in the following aspects: (i) explicit EV priority solutions on highway segments are proposed that do not entail pull-over; (ii) The proposed method is able to guarantee the desired speed of emergency vehicles in feasible traffic conditions ; (iii) The influence of EVs on the normal traffic flow is minimized; (iv) The proposed method could help in EV routing problems by identifying and suggesting better paths with higher operational EV speed, with only aggregated traffic density data.
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