Autonomous Control Of Fully-actuated Coordinated Signals Capable Of Prioritizing Bus Rapid Transit

In an era where artificial intelligence has helped the traditional industry achieve a leapfrog upgrade,the core technology of intelligent transportation products has begun to transform from the fully automated stage to the intelligent stage.Regrettably,the coordinated signal control technology at the closely-spaced signalized intersection along the arterial is still in a semiautomated stage.The main manifestation is the division of labor and coordination between the traffic engineer and the signal control system.Traffic engineers participate in the collection and analysis of traffic demand and the generation and adjustment of signal timing to varying degrees.In order to realize the full automation of the coordinated signal control technology and open the way for intelligence,an autonomous control of fully-actuated coordinated signals is proposed.For a four-leg signalized intersection that protected left turn,a set of detectors is installed 40 meters away from the stop line of each of the entries of coordinated phase and uncoordinated phase to sense the vehicular demand.Build a two-level control system for the control center and signal controller.From a certain moment in the morning to a certain time in the night,the control center takes a continuous N signal cycle as one step,and the double second exponential smoothing method is applied to predict the expected base green time of the coordinated phase and uncoordinated phase of each intersection at the next step.In order to allocate the split time on demand and achieve the base offset accurately,the control center generates the background coordinated signal timing plan for each intersection at the next step and sends it to the signal controller.Then,the signal controller generates the permissive cut off period and the force-offs according to the background plan,and runs actuated control logic once per second.Next,the green time of coordinated and uncoordinated phases is dynamically adjusted with the goal of serving continuous vehicular demand.The N th signal cycle for each step,the signal controller uploads the data required to generate a new background plan to the control center.Immediately after receiving the new background plan,the transition of the old and new background plans is completed.The Bus Rapid Transit(BRT)is a medium-volume urban public transport system.For urban arterial with median bus-only lanes,a BRT priority control logic is proposed based on the autonomous control of fully-actuated coordinated signals and the goal of accelerating the operation speed of BRT vehicles.The logic can take control of BRT vehicles separately by adopting a BRT phase and sense arrival time of BRT vehicles through installment of 3 types of detectors in bus-only lanes.Additionally,it can also define trigger condition of green extension,early green,phase insertion.Furthermore,compress green time of uncoordinated phases to offer extra green time for BRT phases following vertical equity.The lack of real-time detection data caused by the malfunction of the vehicle detector is a great challenge when the autonomous control of fully-actuated coordinated signals are put into practical application.For the sake of minimizing the damage caused by the failure of the detector to autonomous control of fully-actuated coordinated signals,a fault emergency response strategy is proposed.The detector malfunction is divided into 2 levels,and historical detection data and signal timing data are used to formulate feasible countermeasures for each fault level.The results of VISSIM simulation experiments on typical arterial show that the average vehicle delay of the overall system caused by the autonomous control of fully-actuated coordinated signals is better than the pre-timed signal coordination under the higher traffic demand level.After the BRT priority control logic is activated,the operating speed of the BRT vehicle is significantly increased at medium and high traffic demand levels,the travel time of the social vehicle in coordinated direction has hardly changed,and the average delay of the system vehicle is increased.In the case of 4 kinds of detector failures,the emergency response strategy can avoid noticeably deterioration of the performance of the autonomous control of fully-actuated coordinated signals.