Research On Dynamic Lane Management And Signal Priority Control Method For Emergency Vehicles

Emergency vehicles play a very critical role in saving lives and reducing property losses.In order to reduce the response time of emergency vehicles,it is necessary to implement emergency vehicle priority.Emergency vehicle priority includes priority in space and time,but currently there are almost no emergency lanes on urban roads,and emergency vehicle priority only stays in the time dimension.In response to this problem,domestic and foreign scholars have proposed various signal priority strategies,using pre-emption methods to clear the vehicles in the phase of emergency vehicles in advance,but this has a great impact on the overall traffic efficiency.Therefore,this paper proposes a priority traffic management method for emergency vehicles-a priority signal control model based on dynamic emergency lanes,which uses dynamic emergency lanes to give spatial priority and minimizes vehicle delays at intersections,and proposes corresponding single-point emergency Vehicle signal priority control and coordinated control methods.Finally,the effectiveness of the control strategy is verified.The thesis first analyzes different lane management methods and corresponding operating mechanisms through domestic and foreign literature analysis,and determines that the use of dynamic emergency lanes is the space-level measure to achieve emergency vehicle priority and provides the basis for the core content.Secondly,for dynamic emergency lanes,a signal priority control method for emergency vehicles at a single intersection is proposed.For the different signal states when emergency vehicles send priority requests,red light and green light strategies are designed,combined with dynamic emergency lanes,a lane clearing model is proposed.Aiming at the actual case in Changsha,a case study was carried out on the priority control method of single-point emergency vehicles,and the effectiveness of the control strategy was verified.At the same time,the five aspects of emergency lane time window,green light time,flow,saturation and delay at intersections before and after the implementation of priority are analyzed.The results show that:after priority is implemented,the green time and traffic of each phase are dynamically redistributed,the saturation of the phase where the emergency vehicle is located and the adjacent phase is slightly increased while the saturation of the remaining two phases is decreased to achieve the optimal intersection;as the saturation increases from 0.5 to 0.9,the increase in delay at the intersection after priority gradually increases.But while delays increase,this strategy can significantly increase the operating speed of emergency vehicles;On the whole,although the average delay of vehicles at intersections has increased,the delay of emergency vehicles is reduced to 0.Furthermore,based on the management and control of continuous dynamic emergency lanes,in the case of a small reduction in the green wave bandwidth,considering the benefits of emergency vehicles and social vehicles,based on coordinated control,the minimum delay of intersection groups is the control goal.A combination optimization method of dynamic emergency lane time window and continuous intersection coordinated control is developed to give emergency vehicles a "forced green wave".In addition,a case study was carried out on the actual two consecutive intersections in Changsha.The results show that the green wave bandwidth of the two intersections is reduced by about 21.4%,and the overall vehicle delay of the intersection group has increased by about 8.47%compared to before the implementation of priority.Among them,vehicle delays at intersections 1 and 2 have corresponding increases and decreases respectively.But overall it is still better than the priority control effect of emergency vehicles at single-point intersections.Finally,the t-SNE dimensionality reduction algorithm is used to group the 6 characteristic variables of the two intersections.The grouping results show that the coordinated intersection control method can reduce vehicle delays at downstream intersections in most cases,but overall In all cases,vehicle delays in the intersection group will increase.At the same time,the correlation analysis of the calculated results is done to prove that the proposed method is effective.Finally,the dynamic emergency lane management and signal priority control method for emergency vehicles proposed in this paper uses the traffic simulation platform SUMO to conduct simulation experiments,and uses Matlab to call the TraCI interface to control the realtime lanes and signals at the intersection.The experimental results show that the method proposed in this paper can realize the barrier-free passage of emergency vehicles.For the more congested road sections,the dynamic emergency vehicle road section can be completely cleared within 30s,and the average speed change of other lanes is less than 3%;however,after the priority control is executed,the emergency vehicle is in the phase The queue length of the entrance lane with other phases will be increased accordingly,and it will take several cycles to recover.