The cost of equity: Assessing transit accessibility and social disparity using total travel cost

Social equity is increasingly incorporated as a long-term objective into urban transportation plans. Researchers use accessibility measures to assess equity issues, such as determining the amount of jobs reachable by marginalized groups within a defined travel time threshold and compare these measures across socioeconomic categories. However, allocating public transit resources in an equitable manner is not only related to travel time, but also related to the out-of-pocket cost of transit, which can represent a major barrier to accessibility for many disadvantaged groups. Therefore, this research proposes a set of new accessibility measures that incorporates both travel time and transit fares. It then applies those measures to determine whether people residing in socially disadvantaged neighborhoods in Montreal, Canada experience the same levels of transit accessibility as those living in other neighborhoods. Results are presented in terms of regional accessibility and trends by social indicator decile. Travel time accessibility measures estimate a higher number of jobs that can be reached compared to combined travel time and cost measures. However, the degree and impact of these measures varies across the social deciles. Compared to other groups in the region, residents of socially disadvantaged areas have more equitable accessibility to jobs using transit; this is reflected in smaller decreases in accessibility when fare costs are included. Generating new measures of accessibility combining travel time and transit fares provides more accurate measures that can be easily communicated by transportation planners and engineers to policy makers and the public since it translates accessibility measures to a dollar value.     

Continuous approximation for skip-stop operation in rail transit

Operating speed of a transit corridor is a key characteristic and has many consequences on its performance. It is generally accepted that an increased operating speed for a given fleet leads to reduced operating costs (per kilometer), travel and waiting times (three changes that can be computed precisely), an improved comfort and level of service, which can attract new passengers who are diverted from automobile (items harder to estimate precisely). That is why several operation schemes which aim to increase the operating speed are studied in the literature, such as deadheading, express services, and stop skipping.A novel category of solutions to this problem for one-way single-track rail transit is to perform accelerated transit operations with fixed stopping schedules. The concept is quite simple: as the time required for stopping at each station is an important part of travel time, reducing it would be a great achievement. Particular operations that take advantage of this idea already exist. This paper focuses on one of them: the skip-stop operation for rail transit lines using a single one-way track. It consists in defining three types of stations: AB stations where all the trains stop, and A and B stations where only half of the trains stop (stations type A and B are allocated interchangeably). This mode of operation is already described in the literature (Vuchic, 1973, Vuchic, 1976, Vuchic, 2005) and has been successfully implemented in the Metro system of Santiago, Chile.This work tackles the problem with a continuous approximation approach. The problem is described with a set of geographically dependent continuous parameters like the density of stations for a given line. Cost functions are built for a traditional (all-stop) operation and for skip-stop operation as described above. A simple example is presented to support this discussion. Finally, a discussion about the type of scenarios in which skip-stop operations are more beneficial is presented.     

城市高架轨道交通景观评价体系研究

研究目的:目前国内对于城市高架轨道景观评价的研究尚处于探索阶段,还没有成熟的指标体系及评价方法,为此需首要建立一套较为客观、简捷、实用,又能得到专家和公众认同的景观评价体系。研究方法:本文选用“目标—指标层次结构”模式,就是AHP层次分析方法,从动态景观和静态景观2个方面去构建城市高架轨道交通景观评价体系,并以重庆轻轨2号线中的2个有代表性的区段景观,对该体系进行验证。研究结论:经实例验证,本文建立的城市高架轨道交通景观评价体系能够具体体现出高架轨道景观的差异性,并能反映具体差异点及差异程度。可明确量化地反映高架轨道交通的景观评价等级和其中单项指标的景观等级,并具有可比性,其结果能准确、客观地反映城市高架轨道交通景观的实际情况,方法简单易行,具有实用性。     

浅析“梦幻女神”号110t CPP尾轴和螺旋桨的拆检

以本公司成功完成的16万t散货船"梦幻女神"号110 tCPP尾轴和螺旋桨拆检工程为例,简要介绍了大型CPP尾轴和螺旋桨拆检时遇到的特殊问题、解决方法和技术要求。     

新干线信号通信设备的维修管理体制

系统地描述和分析总结了JR东日本的新干线信号通信设备的维修管理体制.对维修管理系统的管理对象、组织结构、主要任务,以及信号通信系统的中央信息监视系统和维修作业管理系统进行了充分的说明,对我国客运专线的综合维修管理体制的建设有很好的借鉴作用.     

铁路枢纽折角车流数值变化的动态模拟

以解编车流作业规则和系统资源限制为约束,构造不同目标函数下铁路枢纽编组站作业分工数学模型,给出折角车流理论最大值和最小值及相应编组站作业分工方式及车流条件。基于折角车流变化的复杂性和多样性,将外部车流环境视为一个动态的随机输入,以特定铁路枢纽为背景用计算机模拟技术和遗传算法计算不同条件下折角车流数值解。通过对模拟数据趋势变化比较分析,提出铁路枢纽运输组织不应过分追求折角车流最小等结论。     

基于乘客换乘量和停车泊位的BRT站台规模研究

快速公交系统(BRT)的研究在我国尚处起步阶段,目前已有一些城市引进了BRT,为了保证公交的快速通行,对BRT站台规模的研究日益重要。首先找出快速公交站台规模的影响因素,由此结合排队论的相关知识,从站台乘客换乘量和泊位对站台规模的影响进行了深入探讨,提出了基于乘客换乘量和基于泊位的站台规模计算模型。该模型可以计算出站台的最小面积和最小长度;再以最小宽度为验算指标,当指标冲突时,结合调整原则,最终得到合理设置的站台规模。     

上海铁路西站南广场综合交通枢纽规划与设计

基于铁路上海西站枢纽的最新规划方案,在充分虑上海西站改建、城市轨道交通建设、城市综合交通枢纽成及上海西站南广场地块开发的背景下,从地下和地上空利用、设施布局、交通组织等角度,提出了一种新的上海西南广场综合交通枢纽的一体化规划设计方案.其设计理是:以轨道交通为核心,各种交通方式之间无缝衔接、复合同发展的铁路车站站前广场.     

Examining the influence of multidestination service orientation on transit service productivity: a multivariate analysis

Between 1990 and 2000, U.S. transit agencies added service and increased ridership, but the ridership increase failed to keep pace with the service increase. The result was a decline in service effectiveness (or productivity). This marks the continuation of a long-running and often-studied trend. The scholarly literature attributes this phenomenon, at least in part, to transit agency decisions to decentralize their service rather than focus on serving the traditional CBD market. Many scholars argue that a decentralized service orientation is both ineffective and inefficient because it attracts few riders and requires large per-rider subsidies. This research tests whether a non-traditional, decentralized service orientation, called multidestination service, results in reduced service productivity. Contrary to what the literature suggests, we find that MSAs whose transit agencies pursued a multidestination service orientation did not experience lower productivity. These results indicate that policies that have encouraged the growth of decentralized transit services have not necessarily been detrimental to the industry.

基于逆向重力模型的枢纽机场旅客吞吐量估计方法

为了利用航空OD客流数据精确估计机场旅客吞吐量,描述了全连通线性航线网络和枢纽辐射航线网络,根据枢纽机场之间的OD客流矩阵,建立了逆向重力模型标准代数算法和基于哈密顿图原理的简化代数算法,分析了在不同距离修正指数下,算法的拟合与估计精度。分析结果表明:简化代数算法与模型标准代数算法最优吞吐量回归直线的可决系数都为0.84,斜率分别为0.91和0.87,比较接近。可见算法的拟合效果优良,估计精度高,且简化代数算法需要的数据少,尤其适合大规模OD矩阵分析。