Research On Influencing Mechanism Of Coordinated Arterial Signal Control On Traffic Safety Based On Simulation

Arterial signal coordination control is one of the most effective approaches to tackle urban traffic congestions,which can significantly improve the operational efficiency at the intersections and vehicular velocities along the roadway segment.However,the signal coordination also brings about a series of safety concerns for the various driving cohorts.Studies have shown that because the signal coordinated control system integrates adjacent intersections and sections into a whole part,it creates new characteristics for traffic safety.To this end,it is necessary to study the mechanism of the influence of coordinated control of artery signals based on traffic safety.Based on the program of NSFC(Natural Science Foundation of China)"Traffic-safety Oriented Arterial Signal Coordination Theory and Technique",this research attempts to the interactive mechanism how the signal coordination parameters affect the traffic safety.The research based on traffic investigation and real signal control files,uses VISSIM and Synchro to establish a microscopic simulation system of arterial signal coordination control.The vehicle trajectory file generated by the simulation is processed by SSAM(Surrogate Safety Assessment Model),and the traffic conflict is extracted and analyzed to indirectly evaluate its traffic safety.By analyzing the difference of conflicts number,conflict severity(TTC,PET)and the degree of dispersion due to different traffic and signal control parameters,this paper attempts to the interactive mechanism how the signal coordination parameters affect the traffic safety:1.The types of conflicts are classified,and the TTC is determined as the severity judgment index due to the characteristics of arterial signal coordination system.The classification of traffic conflict severity is therefore proposed(serious conflict: TTC<1.1s;slight conflict: TTC>1.4s).2.There are significant impacts on the number of conflicts and little effect on the severity of the conflict due to the change of traffic flow(flow rate,vehicle density and speed limit)and signal control(period length and the phase difference)parameters.3.The parameters have different effects on the safety of the arterial signal coordination system.In general,when the efficiency of the arterial signal coordination system is the best(two-way green wave band is the widest),there are more but slight traffic conflicts.4.It is recommended to reserve sufficient flow increment when planning an arterial signal coordination system,and adopt a higher road section speed limit(50-85Km/h),and also adopt the most efficient signal period and phase difference to obtain the best traffic efficiency and traffic safety.This paper compensates the limit of safety impact mechanism of the arterial signal coordination system.The research will help to develop a new generation of arterial signal coordination system theory and techniques while accounting for both safety and efficiency,which will eventually provide scientific bases and supports for the signal control and management.