In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-...In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-following and lane change influenced by an adjacent vehicle, and the model for control and optimization of intersection with signal. Optimization of the traffic signal timing with a genetic algorithm and a microscopic simulation is carried out. It represents a novel approach to solving optimal signal timing.展开更多
In a coordinated road network,the optimal common cycle time is determined by evaluating the performance of the network in the given range of cycles. Normally,this range is determined by users 'experience. And a la...In a coordinated road network,the optimal common cycle time is determined by evaluating the performance of the network in the given range of cycles. Normally,this range is determined by users 'experience. And a large range of common cycle time,e. g. [30,200] is chosen,which requires long computation time. This study considers that the optimal common cycle time ranges between the minimal and maximal value of intersections' individual optimal cycle time. It is proved mathematically from the convexity condition,that the delay of the network and each individual intersection are convex functions of the cycle time according to Webster delay model. Finally,2 000 random cases for the network composed of two intersections and of eight intersections are created to underline the proposed conclusions. The results of all cases confirm the validity,and show up to 90% improvement in computation time to compare with experience range. The signal optimization tool,Synchro,is also used to validate the conclusion by 50 random cases. The results confirm reliability further.展开更多
Signal retiming is a prominent way that transportation agencies use to fight congestion and change of traffic pattern.Performance evaluations of traffic conditions at signalized intersections and arterials provide act...Signal retiming is a prominent way that transportation agencies use to fight congestion and change of traffic pattern.Performance evaluations of traffic conditions at signalized intersections and arterials provide actionable data for agencies to make well-informed and prioritized signal retiming decisions.However,the abundance of data sources,the lack of standardized evaluation methods and oftentimes the shortage of resources make it a difficult endeavor.The review detailed in this paper examines the advances made in traffic signal performance evaluation.We establish the necessity for the evaluations,study the process of continuous improvement of traffic signal performance using the evaluations,and then examine multiple methodologies in a plethora of research endeavors.Particularly,we focus on probe vehicles and sensors data,the two major sources of data.We discuss how sensors are connected to signal controllers to provide relevant in-depth traffic data including speed and occupancy measures.We also review the nature of probe vehicles and the level of penetration.We then define and summarize performance measures derived from both sources,to aid in performance evaluations.For performance evaluation methods,we discuss the research studies and provide summaries including advantages and disadvantages of the methods used,as well as a holistic outlook for future research.This paper is aimed to provide a comprehensive review on the state-of-the-art to benefit researcher,traffic agencies,and commercial entities that thrive to improve safety and efficiency of traffic signals through performance evaluations.展开更多
文摘In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-following and lane change influenced by an adjacent vehicle, and the model for control and optimization of intersection with signal. Optimization of the traffic signal timing with a genetic algorithm and a microscopic simulation is carried out. It represents a novel approach to solving optimal signal timing.
基金Sponsored by German Aerospace Center(Grant I.MoVe AP3200 Nicht-kooperative Verkehrssteuerung)
文摘In a coordinated road network,the optimal common cycle time is determined by evaluating the performance of the network in the given range of cycles. Normally,this range is determined by users 'experience. And a large range of common cycle time,e. g. [30,200] is chosen,which requires long computation time. This study considers that the optimal common cycle time ranges between the minimal and maximal value of intersections' individual optimal cycle time. It is proved mathematically from the convexity condition,that the delay of the network and each individual intersection are convex functions of the cycle time according to Webster delay model. Finally,2 000 random cases for the network composed of two intersections and of eight intersections are created to underline the proposed conclusions. The results of all cases confirm the validity,and show up to 90% improvement in computation time to compare with experience range. The signal optimization tool,Synchro,is also used to validate the conclusion by 50 random cases. The results confirm reliability further.
基金supported in part by Tennessee Department of Transportation(TDOT)and Federal Highway Administration(FHWA),under TDOT grant RES2021-09
文摘Signal retiming is a prominent way that transportation agencies use to fight congestion and change of traffic pattern.Performance evaluations of traffic conditions at signalized intersections and arterials provide actionable data for agencies to make well-informed and prioritized signal retiming decisions.However,the abundance of data sources,the lack of standardized evaluation methods and oftentimes the shortage of resources make it a difficult endeavor.The review detailed in this paper examines the advances made in traffic signal performance evaluation.We establish the necessity for the evaluations,study the process of continuous improvement of traffic signal performance using the evaluations,and then examine multiple methodologies in a plethora of research endeavors.Particularly,we focus on probe vehicles and sensors data,the two major sources of data.We discuss how sensors are connected to signal controllers to provide relevant in-depth traffic data including speed and occupancy measures.We also review the nature of probe vehicles and the level of penetration.We then define and summarize performance measures derived from both sources,to aid in performance evaluations.For performance evaluation methods,we discuss the research studies and provide summaries including advantages and disadvantages of the methods used,as well as a holistic outlook for future research.This paper is aimed to provide a comprehensive review on the state-of-the-art to benefit researcher,traffic agencies,and commercial entities that thrive to improve safety and efficiency of traffic signals through performance evaluations.
