A new schedule-based transit assignment model with travel strategies and supply uncertainties

This paper proposes a new scheduled-based transit assignment model. Unlike other schedule-based models in the literature, we consider supply uncertainties and assume that users adopt strategies to travel from their origins to their destinations. We present an analytical formulation to ensure that on-board passengers continuing to the next stop have priority and waiting passengers are loaded on a first-come-first-serve basis. We propose an analytical model that captures the stochastic nature of the transit schedules and in-vehicle travel times due to road conditions, incidents, or adverse weather. We adopt a mean variance approach that can consider the covariance of travel time between links in a space–time graph but still lead to a robust transit network loading procedure when optimal strategies are adopted. The proposed model is formulated as a user equilibrium problem and solved by an MSA-type algorithm. Numerical results are reported to show the effects of supply uncertainties on the travel strategies and departure times of passengers.     

Optimization of transport investment and pricing policies: the role of transport pricing in network design

This paper investigates the role of transport pricing in network design and describes two facts about flow pattern in a transportation system. The first, illustrated by an example of Braess paradox, is that adding a new link to the network does not necessarily minimize the total travel time. The second is that introducing of appropriate toll pricing may reduce not only the total network time but also the travel time for each individual traveller. It follows with the investigations of different system objectives and different pricing policies (only toll pricing and distance‐based pricing are considered), and shows how they affect the system performance and flow pattern. Lastly, a systematic optimization process is proposed for integrated planning of transport network and pricing policies.     

Using Focus and NomiNal Group Techniques for a Better Understanding of the Transit Disadvantaged Needs

The research presented in this paper explores the context, method, and value of focus group research in transit needs assessments. Group participatory research can generate data that are not easily obtained by other methods. The paper focuses on lessons from three Nebraska communities whose transit disadvantaged rely on community-based paratransit services. Because of the size of the paratransit population and the inability to control who showed up to the focus group sessions, a modified group research protocol was adopted in order to garner information from whomever attended the session. The population parameters and the number of people at the meetings were anticipated by the researchers and mitigated by incorporating nominal group techniques. Research findings from the focus group sessions are discussed paying particular attention to the candid and policy-specific comments made by the focus group participants. The paper concludes with an application of focus group research in transit planning.     

圈层外推法在交通影响分析中的应用

针对目前交通影响分析实际项目缺乏路段阻抗矩阵这一现实情况,提出了一种基于路段饱和度的交通量分配方法--圈层外推法.由于路段饱和度既与阻抗之间存在显著的相关性,又较易通过观测获得,因此不仅具有很强的理论说服力,而且还具有广泛的实用价值.此外,结合数据结构知识,提出了基于VB的实现算法,并通过实例证明其正确性.     

基于道路设计与交通规划的道路选线优化模型

结合道路设计理论与交通规划理论,以地理信息系统为平台,开发道路选线优化模型。该模型是一个费用指向的优化问题,最小化费用目标函数中包括道路建设费用、土方工程费、道路交通诱发的环境污染的不经济费用,OD交通在路网上总走行时间的时间费用等。优化模型首先随机生成新建道路的空间位置候选方案集,并自动设计新建道路的平曲线和竖曲线,计算新建道路的各项工程费用。然后,对变化的路网进行自动拓扑,通过交通量分配得到OD交通在新路网上的走行时间和交通流特征,计算OD交通的环境负荷。最后,在遗传算法中判断候选方案的优劣,直到得到一个最佳的新建道路的空间位置方案为止。     

一类动态交通分配中的输出流模型及其数值解法

已知路段输入流,基于Greenshields提出的速度-密度关系模型以及Jayakrishnan et.al提出的改进的Greenshields 速度-密度关系模型所描述的路段交通流特征,分别给出了关于路段输出流的常微分方程模型.针对无法得到该模型的解析解,利用龙格-库塔-芬尔格算法给出初始条件下的数值解.在已知输出流的条件下,每个时刻的路段交通流的行程时间也相应给出.仿真结果表明,针对两类不同速度-密度关系所建立的输出流模型,所得到每个时刻的输出流基本相似,但路段行程时间存在明显差异.与交通流调查数据比较,基于改进的Greenshields速度-密度关系的输出流模型的行程时间更接近真实情况.     

Effects of the Los Angeles transit strike on highway congestion

In this paper we investigate the effect of the Los Angeles transit strike on highway congestion through analysis of highway sensor data, using both a before-and-after comparison, and a control group comparison. We found that average 5:00 a.m. to 10:00 p.m. traffic speeds declined by as much as 20% during the strike, and the average length of the rush period increased by as much as 200%, even though increases in traffic were small, despite the fact that transit riders constitute a small fraction of the traveling population. Speeds declined the most at locations upstream from the places where queues normally end. We believe that highways are especially susceptible to congestion during strikes because travelers have little opportunity to adjust and equilibrate their travel patterns, as is possible during ordinary periods of traffic growth.     

随机交通分配中有效路径的定向树搜索算法

交通路网中有效路径的确定方法是进行各类随机交通流量分配的关键技术.文章将交通路网中节点位置的确定性与交通出行中路径选取的有向性相结合,模拟树的生长,提出了一种有效路径的定向树搜索算法.通过将该方法应用于随机用户均衡分配模型,说明了该方法的有效性.     

Implementation of interactive transit information kiosks at New York City transit facilities: Analysis of user utilization and lessons learned

Transit Traveler Information Systems (TTIS) comprise a wide range of technologies that transit agencies use to provide reliable and timely transit-related information to customers. The touch-screen interactive information kiosk is an example of these emerging TTIS technologies. This paper examines the implementation of interactive touch-screen information kiosks, known as “On the Go!” Touch-Screen Travel Stations, at Metropolitan Transportation Authority-New York City Transit (MTA-NYCT) facilities in 2011. It analyzes data from passenger intercept surveys, from the kiosks’ built-in application usage logs and from field observations to understand actual passenger utilization of the kiosks and to assess the implications for transit agencies. The field observations also made it possible to obtain a profile of kiosk users, which sheds light on the concept of the “digital divide.” The findings, presented as lessons learned, can help agencies elsewhere develop guidelines and effective strategies for implementing similar interactive transit information systems.     

Using the built environment to oversample walk,transit, and bicycle travel

Characteristics of the built environment (BE) have been associated with walk, transit, and bicycle travel. These BE characteristics can be used by transportation researchers to oversample households from areas where walk, transit, or bicycle travel is more likely, resulting in more observations of these uncommon travel behaviors. Little guidance, however, is available on the effectiveness of such built environment oversampling strategies. This article presents measures that can be used to assess the effectiveness of BE oversampling strategies and inform future efforts to oversample households with uncommon travel behaviors. The measures are sensitivity and specificity, positive likelihood ratio (LR+), and positive predictive value (PPV). To illustrate these measures, they were calculated for 10 BE-defined oversampling strata applied post-hoc to a Seattle area household travel survey. Strata with an average block size of <10 acres within a ¼ mile of household residences held the single greatest potential for oversampling households that walk, use transit, and/or bicycle.