BRT Signal Priority For Precise Headway Management At Arterials

As a public transportation mode with high service quality and low construction cost,BRT system has become an important part of public transportation network for large and medium-sized cities at home and abroad.In order to meet the travel needs of urban residents and increase passenger flow,BRT lines are usually deployed along urban arterials.Coordinated signal control is usually implemented at closely spaced intersections along the urban arterials,ensuring that vehicles in main direction continuously pass through the downstream intersections.With the popularization and application of motor vehicle detection equipment,actuated coordinated signal control has gradually become the main technical form of traffic signal control at arterials.The generation and adjustment of the signal timing is the key technology of actuated coordinated signal control.It is a challenge to be faced in the development of actuated coordinated signal control technology that how to make the signal controller autonomously generate the background signal timing scheme that meets the predetermined target without human intervention,and how to improve the autonomous control level and intelligence degree of the signal controller in a low-cost and high-efficiency way.To address the problems above,this paper proposes an autonomous control method of actuated coordinated signal based on Kalman filtering model.The control objective of the method is to actively adapt to the long-term fluctuation of the road users' time resource demand,and improve the traffic efficiency and coordination effect of vehicles.The traditional traffic data acquisition equipment is used to establish the observation model of motor vehicle phase base green time demand,and Kalman filter model is used to establish the reduction and prediction model of the base green time demand of the vehicle phase,based on which the description mode of the vehicle phase time resource demand level is constructed.The N signal periods are used as time intervals,and the green time demand of the vehicle phase is used as a guide to establish a dynamic adjustment mode of the background signal timing.The simulation experiment shows that the method can actively adapt to the continuous changes of road users' traffic demand level without human intervention,and effectively improve the traffic efficiency and coordination effect of motor vehicles at arterials.BRT systems generally have the characteristics of large carrying capacity and high frequency,and are suitable for operation control methods based on headway,which means the control objective of operation is to ensure the headway regularity of BRT vehicle with the preceding vehicle in any given road section.The traditional conditional signal priority method based on headway has technical problems such as low traffic efficiency and the limited ability to correct the headway deviation.To address the problems above,this paper proposes a conditional signal priority method that can accurately manage the headway of BRT system based on actuated coordinated signal control technology.The control objective of the method is to eliminate or reasonably exert the blocking effect of the signal light on the operation of the BRT vehicle under the common constraint of time supply characteristic and vehicle coordinated control mechanism,and ensure headway regularity of the BRT vehicle when they pass through the stop line.The method takes the actuated coordinated signal control intersection with the median BRT dedicated lane as the research object,and establishes the BRT priority mode and follow-through mode according to the BRT priority request and the signal running state of the individual intersection.And under the BRT priority mode,the triggering method of 3 types of passage opportunities of BRT phase is established.The simulation results show that the proposed method can effectively correct the headway deviation of the BRT vehicles at the higher level of motor vehicle traffic demand,and it does not have obvious negative impact on the traffic efficiency and coordination effect of the motor vehicle.