Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, ped...Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, pedestrians and bikes (ped/bike) are encountered unsmooth and hazardous crossings when right-turn vehicles encroaching their lanes. Meanwhile, this also causes conflicts between right-turn and through vehicles at the crossing street. To better protect ped/bike at crossings with right-turn vehicles, this paper proposes a concept of “right-turn vehicle box” (RTVB) as a supplemental treatment within right-turn lanes. Sight distance, geometric conditions, and behaviors of vehicles and ped/bike are key factors to consider so as to set up the criteria and to design the suitable treatment. A case study was conducted at an intersection pair in Houston, USA to shape the idea of RTVB, together with driving simulator tests under relevant scenarios. The preliminary crosscheck examination shows that the right-turn vehicle box could possibly provide ped/ bike with smoother and safer crossings. In the interim, the safety and efficiency of right-turn operations were also improved. To further validate the effects, implementation studies should be conducted before the RTVB can make its debut in practice. Future works will focus on the complete warrants and design details of this treatment. Moreover, the concept of “vehicle box” could also be transplanted to other places where turning movement(s) needs assistance or improvements.展开更多
To address situations in which the bus lanes at intersections are idle for long periods, this paper proposes a changeable shared buslane scheme for intersections based on lane signals. This scheme set up two GPS monit...To address situations in which the bus lanes at intersections are idle for long periods, this paper proposes a changeable shared buslane scheme for intersections based on lane signals. This scheme set up two GPS monitoring points for buses in the bus lane of theintersection to monitor the bus approaching the intersection. The lane signals linked to the monitoring points provide car driverswith a signal of whether they can enter the bus lane. This paper establishes an optimization model to maximize the number ofvehicles entering the bus lane and uses numerical example simulations to discuss in detail the optimal monitoring point locations indifferent situations.Without affecting the bus,we obtain the optimal monitoring point setting schemes for several common situationsand compare the total delay for ordinary vehicles in the bus lane of the lane-based signal scheme and a baseline case (without thelane-based signal). The results show that this scheme can effectively reduce vehicle delays at intersections. Finally, we discuss thelimitations of this scheme and directions for future research.展开更多
Through and right-turn shared lanes are widely designed to increase the capacity of through traffic,but they can also cause delays for right-turn vehicles.This study presents a dynamic control method for a shared lane...Through and right-turn shared lanes are widely designed to increase the capacity of through traffic,but they can also cause delays for right-turn vehicles.This study presents a dynamic control method for a shared lane that prioritizes right-turn vehicles at the beginning of the cycle and subsequently allows through traffic to queue in the shared lane for saturated discharge.The traffic wave model is employed to reveal the dynamics of the traffic flow under this control and to derive the relationships among major traffic parameters.Constrained by the major relationship,a linear programming approach to minimize the total queue length is developed to determine the proper values of control parameters,including the shared area length,subordinate signal time lag,and shared or exclusive duration.A sensitivity analysis of the control parameters for different arrival rates and flow ratios is performed.Comparisons are conducted among the dynamic shared lane,the fixed exclusive lane,and the fixed shared lane.The results show that the dynamic control method results in a lower delay for both through and total traffic.展开更多
文摘Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, pedestrians and bikes (ped/bike) are encountered unsmooth and hazardous crossings when right-turn vehicles encroaching their lanes. Meanwhile, this also causes conflicts between right-turn and through vehicles at the crossing street. To better protect ped/bike at crossings with right-turn vehicles, this paper proposes a concept of “right-turn vehicle box” (RTVB) as a supplemental treatment within right-turn lanes. Sight distance, geometric conditions, and behaviors of vehicles and ped/bike are key factors to consider so as to set up the criteria and to design the suitable treatment. A case study was conducted at an intersection pair in Houston, USA to shape the idea of RTVB, together with driving simulator tests under relevant scenarios. The preliminary crosscheck examination shows that the right-turn vehicle box could possibly provide ped/ bike with smoother and safer crossings. In the interim, the safety and efficiency of right-turn operations were also improved. To further validate the effects, implementation studies should be conducted before the RTVB can make its debut in practice. Future works will focus on the complete warrants and design details of this treatment. Moreover, the concept of “vehicle box” could also be transplanted to other places where turning movement(s) needs assistance or improvements.
基金supported by the Natural Science Foundation of Hunan Province(Grant No.2021JJ30822).
文摘To address situations in which the bus lanes at intersections are idle for long periods, this paper proposes a changeable shared buslane scheme for intersections based on lane signals. This scheme set up two GPS monitoring points for buses in the bus lane of theintersection to monitor the bus approaching the intersection. The lane signals linked to the monitoring points provide car driverswith a signal of whether they can enter the bus lane. This paper establishes an optimization model to maximize the number ofvehicles entering the bus lane and uses numerical example simulations to discuss in detail the optimal monitoring point locations indifferent situations.Without affecting the bus,we obtain the optimal monitoring point setting schemes for several common situationsand compare the total delay for ordinary vehicles in the bus lane of the lane-based signal scheme and a baseline case (without thelane-based signal). The results show that this scheme can effectively reduce vehicle delays at intersections. Finally, we discuss thelimitations of this scheme and directions for future research.
基金supported by the National Natural Science Foundation of China(Nos.52325210,52131204,and 52302411)the Shanghai Science and Technology Innovation Action Plan Project(No.19DZ1209004)the Fundamental Research Funds for the Central Universities(No.22120220137).
文摘Through and right-turn shared lanes are widely designed to increase the capacity of through traffic,but they can also cause delays for right-turn vehicles.This study presents a dynamic control method for a shared lane that prioritizes right-turn vehicles at the beginning of the cycle and subsequently allows through traffic to queue in the shared lane for saturated discharge.The traffic wave model is employed to reveal the dynamics of the traffic flow under this control and to derive the relationships among major traffic parameters.Constrained by the major relationship,a linear programming approach to minimize the total queue length is developed to determine the proper values of control parameters,including the shared area length,subordinate signal time lag,and shared or exclusive duration.A sensitivity analysis of the control parameters for different arrival rates and flow ratios is performed.Comparisons are conducted among the dynamic shared lane,the fixed exclusive lane,and the fixed shared lane.The results show that the dynamic control method results in a lower delay for both through and total traffic.
