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Examination of factors affecting freeway incident clearance times: a comparison of the generalized F model and several alternative nested models 下载免费PDF全文
Traffic incidents are a principal cause of congestion on urban freeways, reducing capacity and creating risks for both involved motorists and incident response personnel. As incident durations increase, the risk of secondary incidents or crashes also becomes problematic. In response to these issues, many road agencies in metropolitan areas have initiated incident management programs aimed at detecting, responding to, and clearing incidents to restore freeways to full capacity as quickly and safely as possible. This study examined those factors that impact the time required by the Michigan Department of Transportation Freeway Courtesy Patrol to clear incidents that occurred on the southeastern Michigan freeway network. These models were developed using traffic flow data, roadway geometry information, and an extensive incident inventory database. A series of parametric hazard duration models were developed, each assuming a different underlying probability distribution for the hazard function. Although each modeling framework provided results that were similar in terms of the direction of factor effects, there was significant variability in terms of the estimated magnitude of these impacts. The generalized F distribution was shown to provide the best fit to the incident clearance time data, and the use of poorer fitting distributions was shown to result in severe over‐estimation or under‐estimation of factor effects. Those factors that were found to impact incident clearance times included the time of day and month when the incident occurred, the geometric and traffic characteristics of the freeway segment, and the characteristics of each incident. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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华夏 《青岛远洋船员学院学报》2005,26(4):45-49
本文介绍了以VC++6.0为技术平台实现F77船站手柄话机模拟京统的构想、软件的设计思路、编程技术分析和程序流程图。 相似文献
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综述了当前天然气发动机燃气供给系统的作用和组成,分别阐述了该系统内各个主要器件的作用、原理和典型结构,对于不同特点的混合系统、混合器等做出对比,并对空燃比控制策略作了一些叙述. 相似文献
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以TMS320F2808芯片为控制核心,主电路采用移相全桥电路拓扑结构,设计了一台充电机。文章介绍了其系统原理框图及主要功能的实现。实验表明,此设计是可行的,并简化了系统、降低了成本。 相似文献
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运营高铁精测网复测的核心与难点是线上CPⅡ的稳定性判定与正确更新。在研究分析高铁规范中CPⅡ复测更新指标的基础上,结合多条运营高铁线路复测工程经验,就相邻点间坐标差之差的相对精度易超限的问题,提出新的CPⅡ复测更新判定标准与指标。采用相邻点复测与原测方位角较差分析、CPⅢ自由网平差检核、F检验法,不同方法识别的不稳定点一致,从不同角度论证新的复测更新标准的合理性。理论和实践证明,新的CPⅡ复测更新指标不仅大大减少了点位更新率,且识别出的不稳定点更符合点位实际变动情况,可为相关规范的修订提供参考。 相似文献
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In c-C4F8 and c-C4F8/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the gas density between 150-550 Td by the steady-state Townsend (SST) method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths were obtained by two methods:computing the density-normalized effective ionization coefficient as a function of the overall density-reduced electric field strength; and measuring static breakdown voltages as a function of the product of gas density and electrode separation. Good agreement was obtained by these two methods, which ensures the correctness of the former method. The limiting field strengths of c-C4F8 and c-C4F8/CO2 mixtures were compared with those ofpure SF6, SF6/CO2 mixtures and pure c-C4Fs. It is found that buffer gas CO2 does not reduce the limiting field strengths of c-C4F8 greatly, the limiting field strengths of c-C4F8/CO2 mixtures are higher than those of SF6/CO2 mixtures or even pure SF6, and so c-C4F8/CO2 mixtures are suggested to be possible substitutes for SF6. 相似文献