Control Methods And Simulation Tests For Bus Bunching In Connected Bus Rapid Transit Corridors

Priority development of public transportation is an important strategy to alleviate urban traffic congestion,and the relevant measures taken by many cities include opening Bus Rapid Transit(BRT)corridors and operating multiple high-frequency bus lines.However,due to the limitations of existing bus station berths,hub stations,and signalized intersections,bus bunching often occurs in the urban high-frequency BRT corridors,which will limit the improvement of bus operation efficiency and exacerbate the instability of the bus system.Therefore,it is necessary to analyze the reasons for the phenomenon of bus bunching in BRT corridors and take reasonable measures to effectively alleviate the problem.This paper intends to take the Xiamen BRT system as the research scenario,take connected and automated buses as the research object,start from the causes of bus bunching and combining the characteristics of high-frequency BRT corridors,optimize and adjust the bus station berths,hub stations,bus speed and bus departure schedule in BRT corridors respectively.Firstly,though the analysis of the mismatch between fixed length of station berths and multiple types of buses,an adaptive operation mode for station berths is designed,and two traffic modes for single vehicle departure operation and dynamic platooning operation are proposed respectively.Secondly,based on the traffic mode of adaptive operation for station berths,this paper proposes two control methods for bus bunching under single vehicle departure operation and dynamic platooning operation,and designs three schemes to test their effects of bus bunching control.The results show that the performance of the control method for bus bunching under dynamic platooning operation is better than that under single vehicle departure operation.Then,aiming at the issue of conflict between arrival and departure of bus routes in hub stations,an optimization method for the transport organization of hub stations is proposed,and based on this,the control methods for bus bunching under single vehicle departure operation and dynamic platooning operation are proposed.Three schemes are designed to test their effects of bus bunching control.The results show that the control methods for bus bunching in both single vehicle departure operation and dynamic platooning operation can alleviate the phenomenon of bus bunching in hub stations,and the effect of the latter is better than the former.And then,aiming at the problem of limited decision-making and unstable platoons caused by drivers who can only obtain local traffic information rather than global information during bus platoons driving,an operational speed optimization model for bus platoons considering ecodriving and platoon fusion avoidance is constructed,and the effectiveness of its approximate model is verified.A bus-following model is proposed and validated.Three control strategies are defined,and the above models are tested in four terms of the effect of bus bunching control,operational stability,operational efficiency and fuel economy.The results show that the integrated control strategy combining the two models has significant performance benefits.Finally,aiming at the problem of conflicting shared lanes among multiple lines at BRT corridor intersections,a flow direction priority strategy is proposed,and its definition and corresponding departure schedule combination adjustment method are given.Three control strategies are defined,and the method combining vehicle dynamic platooning,adaptive berth operation,and flow direction priority is tested in two terms of the effect of bus bunching control and operational stability.The results show that the integrated control strategy combined with flow direction priority can effectively alleviate the bus bunching near signalized intersections.Therefore,with the help of intelligent networking technology,controlling the problem of bus bunching in BRT corridors can alleviate the phenomenon of bus bunching,which is conducive to improving the operational efficiency and stability of the BRT system,and reducing the fuel consumption of buses,thus reducing the severity of urban traffic congestion to a certain extent.