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文章基于Braess悖论,以单位车辆的平均出行时间为最优目标,以网络道路系统为约束条件,从逆向思维角度建立了通过临时关闭道路引导交通流以缓解城市道路交通拥挤的Narsh均衡非线性规划模型,并以北京二环道路网络为研究对象进行了实例分析。结果表明,在城市道路网中,关闭部分路段并不能明显缓解交通拥堵现状,但可以在不影响路网整体通行时间的条件下改善路网局部拥堵状况。建议城市道路交通临时疏导方案应该根据路网交通流的分布特点和道路通过能力等因素进行制订。 相似文献
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基于K短路,通过使用Logit配流模型研究道路交通网络在多路径流量分配时的性质。首先,研究了Logit模型中参数θ与配流结果之间的关系,从路网平均阻抗与路段阻抗方差最小的角度出发,选择合适的θ值对路网流量进行分配;之后,使用Yen算法求解K短路问题以构建可选路径集合;最后,结合算例对K短路在多路径流量分配时的性质进行了研究。实例研究表明,随着参数θ值的增加,路网平均阻抗与路段阻抗方差先减小后增加,当θ?=1时路段阻抗方差最小;随着K值的减小,路网平均阻抗与路段阻抗方差持续增加,当K=5时路网平均阻抗和路段阻抗方差都在可接受范围之内且计算量最小。本文加深了对于K短路的认识,有利于K短路在实际运用中的推广。 相似文献
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在公路网络交通流量分配过程中,如果不考虑道路收费对路权函数的影响,将不能如实地反映实际情况下路网各路段流量分配情况。以《Transtar——交运之星》公路交通版为开发平台,自行设计了一个应用程序模块来研究公路收费对网络交通流的影响,并给出一简单实例。 相似文献
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《综合运输》2017,(8)
多数研究认为货主是完全理性的,面对多种运输方式可供选择的情况下,货主总是选择广义运输费用最低的运输方式,从而建立制约铁路部门希望收益最大的模型。实际上人们无法做到完全理性,人们获取信息的能力与认知能力都不一样。在传统的铁路运价研究当中双层规划模型运用较为广泛,但是该模型通常基于期望效用理论。在交通领域网络交通流的分配问题上有很多基于累积前景理论的研究,前景理论可以解决在不确定情况下的决策问题,运用该理论解决铁路运价问题的研究很少。本文基于累积前景理论的知识,建立各运输方式前景值的函数,并假设货主总是寻求前景值最大,从而货流达到基于前景理论的用户均衡状态或者是最优状态并建立下层模型,同时进一步研究货流在路网中的分配规律,分别讨论UE均衡和SO最优,研究两种情况下模型之间的关系,最后建立与之相互制约的铁路部门追求收益最大的模型,运用常用的灵敏度启发式算法计算合理的运价。 相似文献
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城市路网交通拥堵评判方法研究一直是拥堵评判技术领域内的重点、难点问题之一。交通拥堵指数模型能够把复杂的城市路网交通运行状况进行简单化、透明化,并能应用到其他城市或区域路网评判体系研究中。文章提出了基于交通拥堵指数模型的一般性交通拥堵评判方法,介绍了该模型各评判指标的计算过程。并以兰州市七里河区和城关区的路网交通为例,对该模型的实用性进行验证,最终得出两城区整体交通拥堵规律及指数变化趋势,说明了该评判方法的可行性和有效性。 相似文献
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为改变目前我国道路信号配时方案与实际交通流不匹配的情况,提高道路交叉口的通行能力,增加绿灯的使用率,提出基于Python与Tensorflow的交通信号决策系统。介绍交通信号决策系统的整体框架及各个模块的层次关系,详细说明每部分的原理及实现方法。通过Python在互联网上实现实时交通数据自动采集,将搜集的数据分类存储。采用TensorFlow框架建立车速预测模型,通过机器学习不断调整优化模型。根据优化后的车速模型预测未来交通流状态变化趋势,交通信号决策系统能够在不同的交通流状态下自适应决策采取不同的绿波信号配时方案。通过VISSIM仿真结果表明,交通信号决策系统能够显著降低道路的拥堵程度,有效降低了道路机动车的停车次数和停车延误,极大地提高路网的运行效率,增大区域协调控制系统的自动化。 相似文献
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随着国家经济建设脚步的加快,路桥的建设技术也在不断的进步,危旧桥梁的加固处理也成为桥梁建设的热点话题之一。因为公路车流量的增多,在上世纪末建设的桥梁一直都存在过载使用的问题,过多的重型车辆对危旧桥梁的使用也是一项巨大的考验。在一些使用年限比较久的桥梁中,出现了桥体老化现象。本文就危旧桥梁加固的有关技术问题进行了探讨。 相似文献
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《Transportation Research Part A: Policy and Practice》1999,33(6):433-448
A novel traffic signal control formulation is developed through a mixed integer programming technique. The formulation considers dynamic traffic, uses dynamic traffic demand as input, and takes advantage of a convergent numerical approximation to the hydrodynamic model of traffic flow. As inherent from the underlying hydrodynamic model, this formulation covers the whole range of the fundamental relationships between speed, flow, and density. Kinematic waves of the stop-and-go traffic associated with traffic signals are also captured. Because of this property, one does not need to tune or switch the model for the different traffic conditions. It “automatically” adjusts to the different traffic conditions. We applied the model to three demand scenarios in a simple network. The results seemed promising. This model produced timing plans that are consistent with models that work for unsaturated conditions. In gridlock conditions, it produced a timing plan that was better than conventional queue management practices. 相似文献
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《Transportation Research Part D: Transport and Environment》2001,6(1):37-60
This article presents a new approach to microscopic road traffic exhaust emission modelling. The model described uses data from the SCOOT demand-responsive traffic control system implemented in over 170 cities across the world. Estimates of vehicle speed and classification are made using data from inductive detector loops located on every SCOOT link. This data feeds into a microscopic traffic model to enable enhanced modelling of the driving modes of vehicles (acceleration, deceleration, idling and cruising). Estimates of carbon monoxide emissions are made by applying emission factors from an extensive literature review. A critical appraisal of the development and validation of the model is given before the model is applied to a study of the impact of high emitting vehicles. The article concludes with a discussion of the requirements for the future development and benefits of the application of such a model. 相似文献
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This article addresses the problem of modeling and estimating traffic streams with mixed human operated and automated vehicles. A connection between the generalized Aw Rascle Zhang model and two class traffic flow motivates the choice to model mixed traffic streams with a second order traffic flow model. The traffic state is estimated via a fully nonlinear particle filtering approach, and results are compared to estimates obtained from a particle filter applied to a scalar conservation law. Numerical studies are conducted using the Aimsun micro simulation software to generate the true state to be estimated. The experiments indicate that when the penetration rate of automated vehicles in the traffic stream is variable, the second order model based estimator offers improved accuracy compared to a scalar modeling abstraction. When the variability of the penetration rate decreases, the first order model based filters offer similar performance. 相似文献
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城市轨道交通线网规划的客流预测模型及应用 总被引:1,自引:0,他引:1
文章根据轨道交通线网规划客流预测的目标、要点、年限和内容,建立了包含出行生成预测、出行分布预测、交通方式分担预测和交通分配预测的四阶段法预测模型,并利用该模型对兰州市轨道交通线网规划的四种方案进行了客流预测,得出最优方案。 相似文献
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This paper examines the impact of having cooperative adaptive cruise control (CACC) embedded vehicles on traffic flow characteristics of a multilane highway system. The study identifies how CACC vehicles affect the dynamics of traffic flow on a complex network and reduce traffic congestion resulting from the acceleration/deceleration of the operating vehicles. An agent-based microscopic traffic simulation model (Flexible Agent-based Simulator of Traffic) is designed specifically to examine the impact of these intelligent vehicles on traffic flow. The flow rate of cars, the travel time spent, and other metrics indicating the evolution of traffic congestion throughout the lifecycle of the model are analyzed. Different CACC penetration levels are studied. The results indicate a better traffic flow performance and higher capacity in the case of CACC penetration compared to the scenario without CACC-embedded vehicles. 相似文献
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In this paper, we develop a macro traffic flow model with consideration of varying road conditions. Our analytical and numerical results illustrate that good road condition can enhance the speed and flow of uniform traffic flow whereas bad road condition will reduce the speed and flow. The numerical results also show that good road condition can smooth shock wave and improve the stability of traffic flow whereas bad road condition will lead to steeper shock wave and reduce the stability of traffic flow. Our results are also qualitatively accordant with empirical results, which implies that the proposed model can qualitatively describe the effects of road conditions on traffic flow. These results can guide traffic engineers to improve the road quality in traffic engineering. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献