Estimating percent-time-spent-following on two-lane rural highways

This study concentrated on estimating the percent-time-spent-following (PTSF) on two-lane highways. This measure is a key estimate of level-of-service in traffic engineering applications. Its evaluation to date has been based on simulations that yielded over-estimated values. The present study shows how to estimate this variable from easily obtained field data based on queuing theory. The estimates accord with opinions on yielding significantly lower values of PTSF that are expressed in the relevant traffic literature. An improved relationship between PTSF and two-way flow is provided by fitting the new estimates by means of the least-squares method.     

Platooning on two-lane two-way highways: An empirical investigation

This paper presents an empirical investigation into platooning on two-lane two-way highways. The main objective is to better understand this phenomenon that has important implications on traffic performance and safety. Field data from three study sites in the state of Montana were used in this study. Separate investigations were performed to examine the relationships among platoon-related variables, namely; time headway, travel speed, and platoon size. The study confirmed that interaction between successive vehicles in the traffic stream generally diminishes beyond a time headway threshold value that fell in the range of 5–7 seconds. Also, the study revealed that very short headways (less than one second) are more associated with aggressive driving and higher speeds than with slow-moving platoons due to lack of passing opportunities. Further, the study found that amount of impedance to traffic is proportional to the size of platoon as evidenced by the relative difference between mean speed of various size platoons and the mean speed of unimpeded vehicles. The study provided other valuable insights into the platooning phenomenon on two-lane highways that are essential in developing a better understanding of traffic operation on two-lane highways.     

Agricultural vehicles and sustainable safe road traffic: solving conflicts on arterial highways

Addressing the issues of traffic safety in rural areas presents a constant challenge. The mix of light and heavy vehicles and the considerable differences in speed among these traffic participants result in high risks and delays for the faster vehicles. Agricultural vehicles (AVs) in particular have such an impact on traffic, especially when using arterial highways. This paper reviews the problems of safety and delays that AVs cause on arterial highways, and the appropriate mitigation. The concept of 'sustainable safety' in The Netherlands focuses on these problems, because of the proposed construction of parallel roads alongside all arterial highways. However, Dutch accident statistics cannot justify the high costs for the construction of parallel roads alongside 7000 km of arterial highways. Delays experienced by fast traffic are another reason for separating AVs from other road users with parallel roads. Alternative measures alongside the arterial highway, such as passing bays, restricting AVs to travelling at off-peak only and improving the conspicuity of the AVs, may be more cost-effective ways of reducing delays and/or improving traffic safety on arterial highways. Another solution may be to eliminate the need for AVs to use the arterial highway by altering their routes. For this purpose, land reallocation projects (as practised in Holland) can provide a useful tool.     

高速公路改扩建工程车速限制方案研究

基于高速公路限速标准、限速方法以及改扩建高速公路的特征,围绕道路线形、特殊道路设施与事故率等方面着重分析了改扩建高速公路限速方案制定的依据及考虑因素,在符合相关法律法规的范围内提出适合我国改扩建高速公路限速研究及方案制定的思路及流程,并通过广东某改扩建高速公路的限速方案制定以详细介绍制定流程。     

New models for financing and managing highways: asset-based road corporations in China

The China International Engineering Consulting Corporation undertook, in 1997, the study of Viability of Asset Based Road Corporations in China as part of the World Bank's transport sector program review. The purpose was to investigate, in a case study format, road administration in China with two specific objectives: to compare (toll) road management in different provinces and to investigate the financial viability of China's toll roads.This paper shows that the three case projects studied, each having different management structures, are all financially viable given the present financing arrangements. However, should the projects be immediately subject to market interest rates and loan maturities prevailing in China today, their financial viability would be uncertain.In a broader context, the World Bank's lending program has enabled China to experiment with different kinds of toll road management structures. These models have both advantages and disadvantages and seem to fit that province's political economic environment in which they are employed. The toll roads and, especially, the impacts of the toll road management and financing arrangements on road administration present challenges to road administration rarely faced even in the developed countries. The challenges involve questions of the congruence of public good and private interest, as well as the role of planning and public accountability – all serious questions as China moves forward in development. These questions are raised in the context of the case studies.     

New highways and land use change: Results from a quasi-experimental research design

Understanding links from new highway construction or capacity expansion to regional growth patterns is crucial for transportation planners and policy makers. In this paper, we incorporate a lagged adjustment regional growth model into a quasi-experimental research design to examine the association between new highway investments and land use change in three California counties. Our study areas provide a mix of urban, small town, and exurban highway projects in order to explore the different effects across project types and geographic contexts. The central finding of this research is that while improvements in surface transportation infrastructure can have large impacts on growth patterns, the nature of the effect depends on the context of the highway investment.     

Immigrant status and commute distance: an exploratory study based on the greater Golden Horseshoe

With 8.76 million residents in 2011, the population of Southern Ontario’s Greater Golden Horseshoe (GGH) has grown dramatically over the past decades, driven by net domestic in-migration and immigration. Corresponding to its growth in population, commuting distances and times within the region have grown as well. Yet, despite the number of immigrants that the region attracts on a yearly basis, there is comparatively little information on commute distances. Consequently, this paper examines commuting distance amongst immigrants in the GGH. Specifically, it evaluates commute distance by immigrant status (immigrants and native born), along with how commute distance differs by arrival cohort and ethnic and racial population groups. Results indicate that commute distance increases with increasing duration of residence, with differences by race and ethnicity.     

School choice: understanding the trade-off between travel distance and school quality

Children are traveling longer distances to school, and the share traveling by car is increasing. This paper examines the effects of school attributes on school choice, which in turn gives rise to travel distance and mode choice. It is well known that school quality is capitalized into residential land values. Households willing and able to pay price premiums may choose to live closer to good-quality schools. In contrast, households with less ability to pay are likely to live in places with schools of lower quality. The California public school system has an open enrollment policy, which allows students to transfer out of their neighbourhood school when places are available. When this option is exercised, students may travel longer distances to school compared with students who attend their neighbourhood schools. We used travel diary data from the 2001 Post Census Regional Household Travel Survey to model school destination choices for K-12 students in the Los Angeles region, California. Parents may choose to send their children to neighbourhood schools, other schools within their home district, or out-of-district schools. We find that location, school quality, and other school features influence the probability of a school being chosen, and the extent to which these factors influence choice varies depending on the characteristics of the residential district and the attributes of the household.     

极软岩3车道大断面公路隧道设计与研究

以按欧洲标准设计的阿尔及利亚东西高速公路极软岩隧道为例,分析了极软岩的工程地质特性;从二次衬砌断面、锚杆设计、拱架选型、进洞方案等方面,介绍了该隧道的设计经验,并分别按照中国规范和欧洲标准进行了设计方案对比,分析了两种规范体系的隧道设计理念差异.通过分析比较,提出了"在以极软岩为主的隧道中,拱顶和边墙采用单心圆断面,减少系统锚杆数量,增强拱架刚度,适当增大洞口开挖高度"的建议.这对于国内同类隧道的设计、施工具有一定的借鉴作用.     

郑西客专高桥隧道下穿既有铁路设计与施工

郑西客专高桥隧道出口下穿既有南同蒲铁路段集成了特浅埋、大断面、新黄土、小角度下穿等技术难点,由于浅埋、新黄土隧道施工易发生较大变形甚至突然性塌方,为确保下穿段施工安全和既有线运营安全、同时保证隧道建设工期,通过技术经济比选,最终确定采用超前管棚+双层支护+台阶法方案。现场通过地表对既有线进行加固、洞内100 m长管棚超前支护和双层喷锚支护,以及仰拱快速封闭等技术手段,实现了采用台阶法安全、快速下穿通过既有铁路段的目的。文章介绍了方案比选情况和现场施工情况,对试验测试情况进行了总结分析,对大断面黄土隧道下穿既有铁路段采用双层支护台阶法的适用性进行了评价,并提出了其技术关键和相关注意事项,为类似工程提供了一种新的建设思路。     

Mobile ICTs and physical mobility: Review and research agenda

The question of the relationship between the spread of communication tools and the physical mobility of individuals is not new and arose with the arrival of the fixed telephone and, more recently, the development of the Internet and especially e-commerce. The extraordinary spread of individual, especially portable, communication tools like the mobile phone, has recently generated new interest in this topic in the fields of transportation economics, geography and sociology. This article discusses the main topics that have been explored, from the debate between complementarity and substitution to analyses in terms of interactions with the spatiotemporal organization of daily activities, the size and maintenance of social networks, and, finally, perception of travel and spaces. We then identify several issues that we think merit further exploration.     

Steering short-term demand for car-sharing: a mode choice and policy impact analysis by trip distance

Transportation - Car-sharing could have substantial benefits. However, there is not enough evidence about if more people choosing car-sharing would reduce private car usage or public transport...     

Traveled distance,stock and fuel efficiency of private vehicles in Canada: price elasticities and rebound effect

This paper presents estimates of the rebound effect and other elasticities for the Canadian light-duty vehicle fleet using panel data at the provincial level from 1990 to 2004. We estimate a simultaneous three-equation model of aggregate demand for vehicle kilometers traveled, vehicle stock and fuel efficiency. Price and income elasticities obtained are broadly consistent with those reported in the literature. Among other results, an increase in the fuel price of 10% would reduce driving by ~2% in the long term and by 1% the average fuel consumption rate. Estimates of the short- and long-term rebound effects are ~8 and 20%, respectively. We also find that an increase in the gross domestic product per capita of 10% would cause an increase in driving distance of 2–3% and an increase of up to 4% in vehicle stock per adult. In terms of policy implications, our results suggest that: (1) the effectiveness of new fuel efficiency standards will be somewhat mitigated by the rebound effect and (2) fuel price increases have limited impacts on gasoline demand.

Values of travel time in Europe: Review and meta-analysis

This paper reports the most extensive meta-analysis of values of time yet conducted, covering 3109 monetary valuations assembled from 389 European studies conducted between 1963 and 2011. It aims to explain how valuations vary across studies, including over time and between countries. In addition to the customary coverage of in-vehicle time in review studies, this paper covers valuations of walk time, wait time, service headway, parking space search time, departure time switching, time in congested traffic, schedule delay early and late, mean lateness and the standard deviation of travel time. Valuations are found to vary with type of time, GDP, distance, journey purpose, mode, the monetary numeraire and a number of factors related to estimation. Model output values of time compare favourably with earnings data, replicate well official recommended values obtained from major national studies, and are transferable across countries. These implied monetary values serve as very useful benchmarks against which new evidence can be assessed and the meta-model provides parameters and values for countries and contexts where there is no other such evidence.     

Hedonic modeling of commercial property values: distance decay from the links and nodes of rail and highway infrastructure

Transportation - This study investigates the impacts of positive and negative externalities of highways and light rail on commercial property values in Phoenix, Arizona. We hypothesize that the...     

城乡客运一体化枢纽场站选址研究综述

随着城乡客运一体化的发展,客运场站基础设施的研究已成为城乡客运一体化领域中的一个重要课题。本文对比分析了国内外研究成果,对不同形式的枢纽选址、运输枢纽场站选址算法、运输枢纽场站评价指标和客运枢纽场站布局方案评价方法的研究现状进行系统的梳理和述评;综述了客运枢纽场站选址研究的发展及该领域的一些主要研究成果,指出了该领域现有研究存在的问题和局限性,并提出了进一步深入研究的方向。     

站场完整性管理技术研究

管道完整性管理技术已经基本实现了工业化应用,然而站场完整性管理作为管道系统完整性管理的一部分还没有引起足够的重视,但是站场完整性管理很重要。介绍了基于资产完整性管理（AIM）的站场完整性管理技术概念及特点;接着对比了国内外的发展差距,重点介绍了站场完整性技术核心方法;最后指出了国内开展站场完整性管理发展的方向。