A linear programming formulation for autonomous intersection control within a dynamic traffic assignment and connected vehicle environment

This paper develops a novel linear programming formulation for autonomous intersection control (LPAIC) accounting for traffic dynamics within a connected vehicle environment. Firstly, a lane based bi-level optimization model is introduced to propagate traffic flows in the network, accounting for dynamic departure time, dynamic route choice, and autonomous intersection control in the context of system optimum network model. Then the bi-level optimization model is transformed to the linear programming formulation by relaxing the nonlinear constraints with a set of linear inequalities. One special feature of the LPAIC formulation is that the entries of the constraint matrix has only {−1, 0, 1} values. Moreover, it is proved that the constraint matrix is totally unimodular, the optimal solution exists and contains only integer values. It is also shown that the traffic flows from different lanes pass through the conflict points of the intersection safely and there are no holding flows in the solution. Three numerical case studies are conducted to demonstrate the properties and effectiveness of the LPAIC formulation to solve autonomous intersection control.     

城郊结合部环形交叉口设置对策研究

随着现阶段农村、城市经济的迅速发展,城郊结合部的道路交通在城市对外的干线运输及外围地区入城的集中运输中起着越来越重要的作用.城郊结合部是连接城市和外围的重要组成部分,兼有城市道路和公路的交通性质,其多条道路的结合常采用平面交叉的连接形式.通过对西安城郊结合部环形平交口设置现状的分析,从交通安全和通行能力的角度进行研究,分析其影响因素,并提出相应的措施.     

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针对城市交叉口交通流的特点,提出了一种自适应可变相序的多相位控制算法。该算法依据绿灯相位车队长度和红灯相位车队长度的比较决定绿灯相位是否转移,在不需要绿灯相位转移时,利用模糊神经网络控制器控制绿灯延时长度。不但结合了模糊控制和神经网络控制的优点,而且所给出的算法相序可变,实现了道路交叉口多相位相序可变控制。仿真结果表明,本文设计的模糊神经网络控制器能够有效降低车辆平均延误,满足实时控制的要求。     

基于VISSIM仿真的信号交叉口优化方法研究

传统信号交叉口配时往往只考虑车辆延误指标,存在一些不足。故此,建立了考虑延误和停车次数的信号配时优化模型,提出应用VISSIM仿真软件与信号配时相结合的信号交叉口优化方法,并将该优化方法应用于交叉口优化实例中,仿真评价结果表明：采用该方法优化交叉口效果显著,平均排队长度、平均延误指标下降明显,能够很好地从时间和空间两方面改善交叉口的性能。     

蚌埠市大庆路淮河大桥南岸接线与胜利路交叉方案的论证

针对蚌埠市沿淮河而建的特殊地理环境，处理好淮河大桥接线与城市道路主干道的交叉方式非常重要，故有必要对淮河大桥南岸接线与蚌埠市城市快速主干道大庆路的交叉方案进行定性、定量的分析比较及论证。这也可以为其他类似施工提供参考。     

公路平面交叉口安全诊断方法研究

公路平面交叉口安全诊断方法是从平面交叉口现有的状况出发,以工程的角度,采用非事故分析、现场调查来判断产生交通事故发生的可能原因,并根据实践经验和理论分析的一种预防性方法。通过一个具有实践意义、可行、有效的简单工具辅助管理部门,改善交叉口安全,提高公路系统的交通安全。     

A continuous-flow-intersection-lite design and traffic control for oversaturated bottleneck intersections

Oversaturation has become a severe problem for urban intersections, especially the bottleneck intersections that cause queue spillover and network gridlock. Further improvement of oversaturated arterial traffic using traditional mitigation strategies, which aim to improve intersection capacity by merely adjusting signal control parameters, becomes challenging since exiting strategies may (or already) have reached their “theoretical” limits of optimum. Under such circumstance, several novel unconventional intersection designs, including the well-recognized continuous flow intersection (CFI) design, are originated to improve the capacity at bottleneck intersections. However, the requirement of installing extra sub-intersections in a CFI design would increase vehicular stops and, more critically, is unacceptable in tight urban areas with closed spaced intersections. To address these issues, this research proposes a simplified continuous flow intersection (called CFI-Lite) design that is ideal for arterials with short links. It benefits from the CFI concept to enable simultaneous move of left-turn and through traffic at bottleneck intersections, but does not need installation of sub-intersections. Instead, the upstream intersection is utilized to allocate left-turn traffic to the displaced left-turn lane. It is found that the CFI-Lite design performs superiorly to the conventional design and regular CFI design in terms of bottleneck capacity. Pareto capacity improvement for every traffic stream in an arterial system can be achieved under effortless conditions. Case study using data collected at Foothill Blvd in Los Angeles, CA, shows that the new design is beneficial in more than 90% of the 408 studied cycles. The testing also shows that the average improvements of green bandwidths for the synchronized phases are significant.     

基于交叉口特征的指路标志建模方法

将指路标志划分为各种路标指示项.结合道路网的拓扑结构,定义了路标指示项的状态函数集,并把路标指示项分为状态性标识、连接性标识和方向性标识3类.交叉口是指路标志必须反映的本质特征,也是指路标志建模的关键.基于交叉口特征函数集的指路标志建模方法是通过交叉口特征函数的运算确定路标指示项的状态函数集.以实际路网交叉口为例,构建了连接性标识模型.     

二级公路路面改建后的交通安全问题浅析

结合二级公路旧路路面改建工程,对其改建后所带来的交通安全问题作分析与讨论。     

城市道路交叉口改造效益评价及实践

通过对城市道路交叉口设计原理及其交通特性分析,运用系统工程的方法选择影响交叉口交通的主要因素及其指标,并给出了重要指标的量化方法。将交叉口改造前后效益值综合量化,作为城市道路交叉口改造效益评价的基本指标,得到了交叉口改造效益评价结果。介绍了以此为基础开发的效益评价软件InEv_1,并以成都市某一交叉口为例,运用InEv_1进行评价。