Research On The Coordinated Control Method For Bus Rapid Transit Vehicle In A Connected Vehicle Environment

Bus rapid transit systems(BRT systems)have become the necessary and irreplaceable ground model of passenger transportation around the worldwide metropolitan cities;however,the increasingly ever-worsening traffic condition has significant and inevitable adverse impacts on the BRT systems.This paper proposed a coordinated control model for BRT vehicles in a connected vehicle environment,which provide the technical system of connected vehicles with solid theoretical support;meanwhile,this also can promote the wide deployment of connected vehicle technologies in the next generation transportation systems.On the other hand,at least to some extent,the proposed method can improve the lever of service of the BRT systems and attract more and more commuters.Hence,it plays an important role in relieving urban traffic congestion,reducing the fuel consumption and exhaust gas emission of traffic and transportation systems.The main research content including the follows:(1)The first important section proposed a coordinated control method for BRT vehicle platoon in a connected vehicle environment based on the basic idea of dynamic speed guidance,and defined the state description parameters of BRT vehicles,the original arrival time interval of BRT vehicle,the initial state of BRT vehicle and the target state of BRT vehicle.Meanwhile,this section also described how BRT vehicle platoon is forming,how to determine the target state of a specific individual BRT vehicle based on its relationship with other BRT vehicles and how to obtain the optimal speed profile based on the initial and target states.The main constraints include the kinetic property of the BRT vehicle,longitudinal safety distance and the boundary of time and space.In addition,the mathematical optimization model was proposed by searching the minimal weighted index of acceleration interference and non-uniform motion time.Finally,the optimization mathematical model was solved by a three-piece-linear speed profile via an improved genetic algorithm.(2)The second main section advanced a reservation-based cooperative transit signal priority(RCTSP)method with connected vehicle technologies,and defined TSP request trigger time stamp,Bus arrival time stamp,Bus arrival time interval,Reservation time stamp and TSP phase insertion and green time reallocation mechanism.The primary constraints include parameters of signal timing scheme,the expected travel speed and the extra dwell time of BRT vehicles.In addition,the optimization mathematical model was formulated as a binary mixed integer nonlinear program(BMINP)based on personal delay time.The BMINP could be solved using the branch-and-bound algorithm or the enumeration method because of the limited number of decision variables and value range.In the sense of realistic implementation,the RCTSP mechanism has three important aspects,including the optimization of signal timing scheme,the dynamic travel speed guidance and the extra dwell time guidance of BRT vehicles.(3)The third major section developed a BRT simulation platform in a connected vehicle environment,which could evaluate the performance of the proposed methods of this paper.Starting from viewpoint of software requirement analysis,this section specified the input and output of the simulation platform,and designed an online traffic simulation framework,some critical classes and its data structure.This BRT simulation platform was implemented in the Visual Studio 2010 integrated development environment via C# and VISSIM 4.3 microscopic traffic simulation software,which provides a solid basis for the assessment,calibration and improvement of the proposed models.The cooperative control model for BRT vehicle platoon and the RCTSP mechanism were simulated in this BRT simulation platform,the evaluation results showed that the cooperative control model has the ability to reduce the vehicle delay time,release the number of stops and improve the sustainability of BRT vehicles.In addition,the RCTSP mechanism outperforms the conventional TSP strategy based on green time extension in all traffic conditions.In a word,the effectiveness of this two models was still considerable in a relatively bad traffic condition.