【目的】在无信号控制的自动驾驶环境下,自动驾驶车辆的通行轨迹将与过街行人产生大量冲突,如何利用交通控制手段使行人安全通过交叉口,并避免对自动驾驶车辆的通行造成较大的干扰,是亟待解决的关键问题。【方法】本文提出一种基于冲突...【目的】在无信号控制的自动驾驶环境下,自动驾驶车辆的通行轨迹将与过街行人产生大量冲突,如何利用交通控制手段使行人安全通过交叉口,并避免对自动驾驶车辆的通行造成较大的干扰,是亟待解决的关键问题。【方法】本文提出一种基于冲突相位组的自动驾驶交叉口行人过街控制方法,将到达交叉口的车辆流向分为4个冲突相位组,在各相位组内单独分配通行时间,基于冲突相位组对自动驾驶车辆和行人过街的通行时间进行建模;在穿插式通行模式的基础上,使用行人信号灯保障行人过街需求,建立考虑行人二次过街的自动驾驶交叉口交通控制模型。模型以交叉口各流向需求量与实际交通量乘积之和最大为目标,以各流向允许车辆通行的时间比例和行人信号灯状态为决策变量,综合考虑交通流量、行人和车辆通行权等约束,建立混合整数线性规划模型(mixed-integer linear program,MILP),该控制模型可为各流向的车辆和行人分配通行权。【结果】本文模型的车均延误较定时控制方案的降低26.74%,较单次过街模型的降低11.53%,人均延误较定时控制方案的降低51.66%,较单次过街模型的降低36.20%。这表明本文模型能有效提升交叉口的通行效率。【结论】本文模型能根据自动驾驶车辆和行人的通行需求,对交叉口时空通行权进行分配,有效保障行人过街安全。展开更多
A cellular automata model is proposed to simulate bi-directional pedestrian flow. Pedestrian movement is investigated by using ant algorithms. Ants communicate with each other by dropping a chemical, called a pheromon...A cellular automata model is proposed to simulate bi-directional pedestrian flow. Pedestrian movement is investigated by using ant algorithms. Ants communicate with each other by dropping a chemical, called a pheromone, on the substrate while crawling forward. Similarly, it is considered that oppositely moving pedestrians drop ＇visual pheromones＇ on their way and the visual pheromones might cause attractive or repulsive interactions. This pheromenon is introduced into mod- elling the pedestrians＇ walking preference. In this way, the decision-making process of pedestrians will be based on ＇the instinct of following＇. At some densities, the relationships of velocity-density and flux-density are analyzed for different evaporation rates of visual pheromones. Lane formation and phase transition are observed for certain evaporation rates of visual pheromones.展开更多
At a typical signalized intersection, the pedestrian phase consists of a walk interval and a change/clearance interval, during which pedestrians are given the right of way. The walk interval is intended to allow pedes...At a typical signalized intersection, the pedestrian phase consists of a walk interval and a change/clearance interval, during which pedestrians are given the right of way. The walk interval is intended to allow pedestrians to exit the curb ramp and enter the crosswalk. The clearance interval will enable them to cross entirely to the other side of the road. Unfortunately, the literature is quite vague on how long the walk interval should be and provides values ranging from 4 to 15 seconds based on qualitative pedestrian demand ranging from Negligible to High. To provide some quantitative guidance for walk interval selection, this paper reports on a study that collected 1,500 pedestrian movement data from 12 signalized intersections with varying pedestrian demand, pedestrian storage areas, and pedestrian push-button locations. The data was used to propose a quantitative model for designers to select the appropriate walk interval. Specifically, this paper seeks to add values to the Traffic Operations Handbook walk-interval guidelines as to how many pedestrians are considered “negligible volume” and can be accommodated by the 4 second minimum time, how many pedestrians are considered “typical volume” and require 7 to 10 seconds, and how many pedestrians are considered “high volume” and require 10 to 15 seconds, or perhaps longer. In addition to examining pedestrian demand, this paper looks at the impact of storage areas and pedestrian push-button location on pedestrian start-up time and, consequently, an appropriate walk interval.展开更多
文摘【目的】在无信号控制的自动驾驶环境下,自动驾驶车辆的通行轨迹将与过街行人产生大量冲突,如何利用交通控制手段使行人安全通过交叉口,并避免对自动驾驶车辆的通行造成较大的干扰,是亟待解决的关键问题。【方法】本文提出一种基于冲突相位组的自动驾驶交叉口行人过街控制方法,将到达交叉口的车辆流向分为4个冲突相位组,在各相位组内单独分配通行时间,基于冲突相位组对自动驾驶车辆和行人过街的通行时间进行建模;在穿插式通行模式的基础上,使用行人信号灯保障行人过街需求,建立考虑行人二次过街的自动驾驶交叉口交通控制模型。模型以交叉口各流向需求量与实际交通量乘积之和最大为目标,以各流向允许车辆通行的时间比例和行人信号灯状态为决策变量,综合考虑交通流量、行人和车辆通行权等约束,建立混合整数线性规划模型(mixed-integer linear program,MILP),该控制模型可为各流向的车辆和行人分配通行权。【结果】本文模型的车均延误较定时控制方案的降低26.74%,较单次过街模型的降低11.53%,人均延误较定时控制方案的降低51.66%,较单次过街模型的降低36.20%。这表明本文模型能有效提升交叉口的通行效率。【结论】本文模型能根据自动驾驶车辆和行人的通行需求,对交叉口时空通行权进行分配,有效保障行人过街安全。
文摘A cellular automata model is proposed to simulate bi-directional pedestrian flow. Pedestrian movement is investigated by using ant algorithms. Ants communicate with each other by dropping a chemical, called a pheromone, on the substrate while crawling forward. Similarly, it is considered that oppositely moving pedestrians drop ＇visual pheromones＇ on their way and the visual pheromones might cause attractive or repulsive interactions. This pheromenon is introduced into mod- elling the pedestrians＇ walking preference. In this way, the decision-making process of pedestrians will be based on ＇the instinct of following＇. At some densities, the relationships of velocity-density and flux-density are analyzed for different evaporation rates of visual pheromones. Lane formation and phase transition are observed for certain evaporation rates of visual pheromones.
文摘At a typical signalized intersection, the pedestrian phase consists of a walk interval and a change/clearance interval, during which pedestrians are given the right of way. The walk interval is intended to allow pedestrians to exit the curb ramp and enter the crosswalk. The clearance interval will enable them to cross entirely to the other side of the road. Unfortunately, the literature is quite vague on how long the walk interval should be and provides values ranging from 4 to 15 seconds based on qualitative pedestrian demand ranging from Negligible to High. To provide some quantitative guidance for walk interval selection, this paper reports on a study that collected 1,500 pedestrian movement data from 12 signalized intersections with varying pedestrian demand, pedestrian storage areas, and pedestrian push-button locations. The data was used to propose a quantitative model for designers to select the appropriate walk interval. Specifically, this paper seeks to add values to the Traffic Operations Handbook walk-interval guidelines as to how many pedestrians are considered “negligible volume” and can be accommodated by the 4 second minimum time, how many pedestrians are considered “typical volume” and require 7 to 10 seconds, and how many pedestrians are considered “high volume” and require 10 to 15 seconds, or perhaps longer. In addition to examining pedestrian demand, this paper looks at the impact of storage areas and pedestrian push-button location on pedestrian start-up time and, consequently, an appropriate walk interval.
