An integer multi-objective optimization model and an enhanced non-dominated sorting genetic algorithm for contraflow scheduling problem

To determine the onset and duration of contraflow evacuation, a multi-objective optimization(MOO) model is proposed to explicitly consider both the total system evacuation time and the operation cost. A solution algorithm that enhances the popular evolutionary algorithm NSGA-II is proposed to solve the model. The algorithm incorporates preliminary results as prior information and includes a meta-model as an alternative to evaluation by simulation. Numerical analysis of a case study suggests that the proposed formulation and solution algorithm are valid, and the enhanced NSGA-II outperforms the original algorithm in both convergence to the true Pareto-optimal set and solution diversity.

Data-driven evacuation and rescue traffic optimization with rescue contraflow control

In response to local sudden disasters,e.g.,high-rise office or residential building fire disasters,road occupation can cause conflicts,and traffic directions may be opposite between evacuation vehicles and rescue vehicles;moreover,lane contraflow can be adopted to meet these surge traffic demands.However,lane contraflow that provides more roads for rescue vehicles reduces the traffic supply in the evacuation direction.It is unclear how to control the number of contraflow roads used by rescue vehicles to coordinate evacuation and rescue traffic operations.Here,we adjust the critical rescue traffic volume of reversing the normal road traffic direction to control rescue contraflow.Additionally,we propose a multiobjective mixed integer linear programming formulation for evacuation and rescue traffic optimization.Additionally,considering that the upper limit of the critical rescue traffic volume is unknown and that the proposed formulation includes multiple objectives and multi-priority vehicle classes,a three-stage solving algorithm is developed.Next,a large-scale evacuation and rescue traffic optimization result dataset is obtained for the Nguyen–Dupuis road network,and the impact of different rescue contraflow control plans on evacuation and rescue traffic is studied based on data-driven sta-tistical analysis.The results show that by adjusting the optimal rescue traffic route,the critical rescue traffic volume for reversing the normal road traffic direction can reduce the interference of rescue traffic to evacuation traffic operation performance without reducing rescue traffic operation performance,and can be used to coor-dinate evacuation and rescue traffic operation under rescue contraflow.

基于模拟驾驶的借道左转驾驶人视觉特性研究

借道左转是一种缓解左转车流压力的新型交通组织方法,通过信号灯时空调配借用对向车道为左转待行区,提高相位内左转车辆通行能力。笔者运用驾驶模拟平台,建立城市道路交叉口借道左转仿真场景;结合眼动追踪系统,获取驾驶人借道左转过程中视觉特性参数的变化;通过瞳孔变化和眼动行为,分析驾驶人心理紧张程度及其与行车风险的关联。结果表明:识读借道左转标识及分隔带开口、到达分隔带开口和到达借用车道停车线几个位置,是驾驶人瞳孔面积变化和持续注视时间、注视兴趣区域变化以及扫视频率骤增的集中点,反映出相应位置驾驶人风险感知强、心理负荷大;借道左转短期注视行为较多,注视时长差距较大,表明该过程驾驶人关注目标多、摄取信息密集且处理难度悬殊,需要进行高强度的信息处理;累计扫视时间占比高于普通左转,且以5°以下小角度扫视为主,反映出借道左转过程环境信息复杂、行车风险较大,驾驶人搜索、对比分析的需求更高,扫视主要是为了捕捉关注目标和补充注视信息。

信控交叉口借道左转设计的延误优化研究

为准确分析交叉口借道左转设计的左转延误,针对现有的延误模型的不足,建立一个合适的延误优化模型,并提升其设置的科学性。先对逆向车道长度进行优化;再通过分析左转车辆的累计到达驶离曲线,以左转总延误最小为优化目标,建立一种新的考虑预信号延误的优化模型;最后,以长沙市芙蓉中路一个交叉口为实例,进行验证,分析左转到达流率对借道左转设计延误的影响及逆向车道长度对左转车均延误的影响。研究结果表明:左转流率越大,越能充分发挥借道左转设计的优势,该模型的左转延误下降可达59.21%;当左转流量偏低时,预信号位置的延误占比较大,随着左转流量的增大,传统车道和逆向车道的延误占比逐步增加。该研究可以准确评价借道左转设计的实用性和优劣程度,对借道左转设计的推广与应用具有重要意义。

Efficient contraflow algorithms for quickest evacuation planning

The optimization models and algorithms with their implementations on flow over time problems have been an emerging field of research because of largely increasing human-created and natural disasters worldwide.For an optimal use of transportation network to shift affected people and normalize the disastrous situation as quickly and efficiently as possible,contraflow configuration is one of the highly applicable operations research(OR)models.It increases the outbound road capacities by reversing the direction of arcs towards the safe destinations that not only minimize the congestion and increase the flow but also decrease the evacuation time significantly.In this paper,we sketch the state of quickest flow solutions and solve the quickest contraflow problem with constant transit times on arcs proving that the problem can be solved in strongly polynomial time O(nm^2(long n)~2)where n and m are number of nodes and number of arcs,respectively in the network.This contraflow solution has the same computational time bound as that of the best min-cost flow solution.Moreover,we also introduce the contraflow approach with load dependent transit times on arcs and present an efficient algorithm to solve the quickest contraflow problem approximately.Supporting the claim,our computational experiments on Kathmandu road network and on randomly generated instances perform very well matching the theoretical results.For a sufficiently large number of evacuees,about double flow can be shifted with the same evacuation time and about half time is sufficient to push the given flow value with contraflow reconfiguration.

Optimal control of automated left-turn platoon at contraflow left-turn lane intersections

Purpose–This study aims to propose a centralized optimal control model for automated left-turn platoon at contraflow left-turn lane(CLL)intersections.Design/methodology/approach–The lateral lane change control and the longitudinal acceleration in the control horizon are optimized simultaneously with the objective of maximizing traffic efficiency and smoothness.The proposed model is cast into a mixed-integer linear programming problem and then solved by the branch-and-bound technique.Findings–The proposed model has a promising control effect under different geometric controlled conditions.Moreover,the proposed model performs robustly under various safety time headways,lengths of the CLL and green times of the main signal.Originality/value–This study proposed a centralized optimal control model for automated left-turn platoon at CLL intersections.The lateral lane change control and the longitudinal acceleration in the control horizon are optimized simultaneously with the objective of maximizing traffic efficiency and smoothness。

信号交叉口借道左转设计方法研究

借道左转作为一种提高交叉口通行能力的交通管理措施,应用广泛。为了使借道左转的使用效果最优,总结借道左转的适用条件和实际运行的4个阶段,提出通过确定左转预信号相位和借道左转车道长度的方法,进行借道左转方案设计。首先,以单位时间借道左转的车辆数为评价标准,分析车道长度变化对借道左转实施效果的影响;其次,归纳出不同参数间的数学关系,得出最优借道左转车道长度与其他变量的转换方法,并推导出合适的左转预信号相位方案;最后,通过VISSIM软件仿真模型进行验证,证明设计方法的有效性。

逆流洗砂机在洗砂工艺中的应用

逆流洗砂机是根据流化床分选原理开发的一种新型洗砂设备,利用了干扰沉降原理实现泥砂的分离。为推动该设备的推广应用,在介绍了设备结构、工作原理和优越性的基础上,进行了现场检测和运行成本分析。结果表明,与传统的轮式洗砂机和螺旋洗砂机相比,逆流洗砂机的洗砂洁净度更高,成品砂含泥量在3%以下,达到国标Ⅱ类砂检测标准;逆流洗砂机在含泥较高情况下的运行成本明显较低,且具有结构简单、自动化程度高、安装方便等优势。逆流洗砂机可用于机制砂脱粉、天然砂脱泥、建筑垃圾回收等领域,是湿法制砂领域砂石水洗的先进设备。

李森科学派——现代遗传学发展中的一股逆流(续完)

From the historical background for the development of T.D.Lysenko School,T.D.Lysenko’s New Genetics,his personal worship and persecution on the scientists in the former Soviet Union,the reactionary essence of pseudoscience of T.D.Lysenko school was deeply exposed and it was pointed put that its perdition was inevitable.At last analysis was made on the cause of occurrence of T.D.Lysenko’s doctrine and historical lessons to be drawn.

大型活动后车道单行优化的双层规划

为了缓解大型活动后疏散期间的拥堵,建立了车道单行优化问题的双层规划模型.该模型考虑了交通组织者与参与者之间的共同作用.模型的上层模型的优化目标是总疏散时间最短,下层模型的优化目标是出行者自身疏散时间最短.将离散粒子群算法用于解决该双层规划问题.用简化的实际交通网络检验优化效果.实验结果表明,基于双层规划模型的车道单行方案能减少总疏散时间20%.

考虑行人和非机动车的借道左转车道设置方法研究

针对借道左转交叉口交通组织方式,研究借道左转车道设置条件,提出了考虑行人和非机动车的主信号、预信号借道左转交叉口配时优化方法,以及进出口车道平衡度评价指标.以苏州市人民路-十梓街交叉口为例进行实证研究,并结合VISSIM仿真,对比分析优化前后交叉口中各车道的延误指标、平衡度指标及二者关联关系.结果表明:优化后交叉口各相位车均延误减少的同时,车道平衡度更加趋向合理,二者之间具有关联性,即延误指标和平衡度指标均能有效评价交叉口的运行情况.

双开口式逆流左转车道几何设计及信号配时优化

为解决单开口式(即仅有1个预信号开口)逆流左转车道(即通过预信号控制动态借用的出口车道)的长度与左转交通需求匹配效果不佳的问题,通过对单开口式逆流左转车道的设计进行分析,提出1种双开口式(即设置2个预信号开口)逆流左转车道的设计及控制方法。结合逆流左转车道的车辆运行规则,分析单开口式、双开口式逆流左转车道上车辆排队行为特征差异,构建逆流左转车道通行能力计算模型和延误计算模型。考虑主预信号协调控制、饱和度、交通波传递等约束条件,以车均延误最小为优化目标,采用0-1变量表示各个预信号开口是否启用,将常规设计、单开口式、双开口式信号配时整合到1个统一的混合整数非线性规划优化模型中,并给出逆流左转车道长度的设计依据。通过案例分析发现:①在逆流左转车道长度为80 m时,交叉口通行能力提升幅度最大;②当通行能力满足需求时,逆流左转车道长度越短,交叉口延误降低越明显;③若为保证通行能力而采用较长的逆流左转车道时,双开口式逆流左转车道通行效率优于单开口式;④综合考虑延误、通行能力等因素,单开口式逆流左转车道长度宜设置为40~60 m,而双开口式宜设置为80 m左右;⑤双开口式逆流左转车道可根据需要选择是否启用每个预信号开口,应用较为灵活,适用于各种流量场景。

借道左转交叉口的适用条件与特性分析

基于车流波动理论和VISSIM软件仿真分析,研究交叉口适宜设置借道左转车道的车流量临界条件。通过波动理论分析得到设置借道左转车道的临界计算公式,以实例计算和VISSIM仿真分析进行验证,并基于VISSIM软件,对交叉口设置借道左转车道前后各运行指标的差异进行对比分析。仿真结果表明,在左转车流量较小并以不饱和流率驶入借道左转车道时,不宜设置借道左转车道,在适宜设置借道左转车道的流量条件下,借道左转车道的设置能有效提高交叉口左转通行能力,并降低左转车辆的平均延误、行程时间、排队长度、停车时间等,借道左转车道的设置不一定会增加左转车辆的停车次数,其与左转车流量有关。

多优先级多车种动态应急交通网络反流策略研究

危化品爆炸泄漏和火灾爆炸等局部突发事件下,疏散车辆与救援车辆在路网上通行的优先级具有差异性。为研究多优先级多车种动态应急交通网络协调优化问题,本文根据多车种的优先级差异性,松弛路段传输模型,模拟疏散和救援交通在路网上的动态加载过程,引入交叉口冲突转向消除与道路反流约束;考虑到优先通行车辆的反流策略会占用低优先级车辆的道路通行能力,设置救援交通的逆行路段数限制。设计分阶段优化方法求解多优先级多车种动态应急交通网络协调优化的多目标混合整数线性规划模型(MPCDETN-MMILP)。最后,以Nguyen-Dupuis路网为例,分析优先通行车辆使用的逆行路段数对疏散和救援交通的影响。算例结果表明:救援交通逆行路段数和对救援车辆迅速到达受灾区域的提升存在上限,且这种提升趋势是逐渐变缓的,而对疏散车辆迅速到达安全区域的抑制呈现波动式的增加趋势;救援交通逆行路段数对救援优先的疏散和救援交通运行优化效果有较大协调作用;连接受灾区域和外部救援场站,且可构成最短径路的路段更会被选择为救援交通逆行路段。

考虑逆向可变车道的预信号公交优先控制

为提高交叉口公交车辆通行效率,提出一种考虑逆向可变车道的预信号公交优先控制方法。假设车辆到达服从均匀分布,基于车流组织规则,构建交叉口车均延误计算模型,再以交叉口人均延误最小为目标,考虑周期时长、饱和度、主预信号控制、功能路段长度等约束,建立信号配时优化模型,最后采用模拟退火算法求解。算例分析结果显示:在交叉口饱和度为0.85的条件下,与常规交叉口、串联交叉口相比,本方法可有效降低人均延误并提高通行能力。通过敏感性分析得出:随着车辆到达率增加,本方法降低人均延误的效果越明显;当直行公交在同向车流中占比25%~35%或左转公交在同向车流中占比15%~25%时,应用本方法效果更好;实际应用中,综合待行区、渐变段等功能路段长度宜取最小临界值。

平面交叉口借道左转设置研究与效果评估

借道左转是平面交叉口左转交通组织方式之一。分析借道左转的设置参数,确定"借道"长度、"借道"车道数的取值范围以及设置借道左转的约束条件,并从道路、交通、信号控制三方面确定适用条件;以一实际交叉口为例进行分析,运用VISSIM软件对其加设借道左转前后的进口道相关指标进行仿真评价,优化借道左转的配时方案,并验证此交叉口设置借道左转车道的可行性以及优势,证明借道左转使交叉口延误降低。研究成果为城市道路交叉口的借道左转设置方案提供决策依据。

一种新型借道左转应用方法

传统借道左转应用方式为直接借用一定长度对向出口车道供本向左转车辆使用,以此缓解左转车道交通压力,提高路口交通通行效率。而在对向出口道通行能力不足的情况下,若本向进口道左转车道通行能力尚有剩余,亦可考虑利用借道左转思维解决问题。通过对借道左转设置的条件进行研究,提出一种新型借道左转应用方法,将本向左转车道借给对向出口车道进行共用,使道路资源得到充分利用,并基于广州市东风东路农林下路路口应用实例,分析该应用方法的有效性。

平面交叉口借道左转组织方式应用研究

为研究借道左转车道组织方式的应用效果,本文以威海市世昌大道-古寨西路交叉口为研究对象,通过道路几何条件和交通控制参数调查,探讨借道左转车道的可实施性,将该交叉口西进口道可变导向车道变为直行车道,同时增设一条借道左转车道。通过Vissim交通仿真对两种左转组织方式的运行评价指标进行对比分析,结果显示:设置借道左转车道使交叉口车辆停车次数、车辆延误、出行时间和排队长度分别减少了7.2%、9.3%、20.6%和30.5%,提高了交叉口的通行能力和服务水平。

基于借道左转的城市道路交通组织方法分析

为了降低道路交叉口车辆延误,提高交叉口通行效能,利用借道左转技术对左转车流量大而左转车道数受限的城市道路交叉口进行车道空间优化。阐述了借道左转的概念和原理,介绍了其适用的交叉口形式与相应设置要求,选取了衢州市衢江中路—新河沿交叉口作为借道左转应用的研究对象。结果表明,借道左转虽在减缓交叉口的车辆延误、缓解交通拥堵、提升道路通行能力等方面具有较显著的应用价值,但该方法的实施具有自身局限性,需根据交叉口实际道路条件和车流量特征综合论证其可行性。

考虑掉头交通流冲突的借道左转组织方法研究

针对设置借道左转车道的路口,借道左转车流易与路口掉头车流产生冲突的问题,提出利用借道左转路段开口进行掉头的解决方法。首先归纳总结了该方法的可实施条件,然后对借道左转方式下车流冲突所产生的延误进行分析,最后根据延误分析拟定解决方案,并对各方案进行仿真。仿真结果表明:可路段掉头借道左转方案的实施能够有效减少路口掉头车流与借道左转车流的冲突,进一步改善交叉口交通流运行状况。