使用浮动车检测路网可达性及交通管理策略的研究

合理的城市道路网结构以及相应的合理的交通管理策略，是缓解城市交通拥挤状况，促进城市健康发展的重要条件，合理、正确、有效地评价和分析道路网结构和现行交通管制方案，对城市道路改进和综合管理具有重要意义。本文在回顾以往评价路网性能的指标和方法的基础上，引入基于浮动车GPS/GIS数据的动态绕行效率的概念，提出了新的利用浮动车数据检测路网可达性、出行机动性，路网切换便捷度和交通管理策略合理性的方法，从浮动车数据的全新角度解释路网重要节点的连接方法和快速路封闭方法对出行的影响。最后利用西直门局部区域进行了示范，通过理论研究和实际应用，说明了利用浮动车GPS/GIS检测数据评估路网切换便捷度、交通管理合理性这一新方法是有效和具有发展前景的。     

城市轨道交通线网形态对换乘便捷性的影响

通过对城市轨道交通线网形态和换乘特点的分析,给出轨道交通线路及线网通达性的量化描述方法。对典型线网通达性的理论计算表明:在同等条件下放射形线网比方格形线网的通达性好,便于换乘;在方格形线网中增加平行线路、斜向线路和环状线路(或弧形线路),对提高线网通达性的贡献依次为较小、较大和最大;在多条线路的交叉点设置换乘站和客运交通枢纽,是提高整个线网通达性、方便乘客换乘的有效措施。通过与莫斯科地铁线网比较,分析北京地铁线网通达性和换乘便捷性方面的不足和原因,提出应该适时选择适宜的线网节点建造多线换乘的客运枢纽站。     

Book reviews

EAST EUROPEAN TRANSPORT: REGIONS AND MODES, edited by B. Mieczkowski. The Hague, Martinus Nijhoff. (F85.00)

CONFLICT IN TRANSPORTATION, by H. M. Steiner, Lexington Mass: D. C. Heath and Lexington Books, 1978. 124 pp.     

The influence of neighborhood types on active transport in China’s growing cities

Rapid urban expansion in China has created both opportunities and challenges for promoting active transport in urban residential communities. Previous studies have shown that the urban form at the city scale has affected active transport in Chinese cities. However, there is less agreement about how the physical and social variations of neighborhood types should be addressed. This research investigates the four most representative neighborhood types found in Chinese cities: traditional mixed-use, slab block work-unit, gated community, and resettlement housing. Household travel diaries conducted in Chengdu in 2016 were analyzed using binary logistic regressions, supplemented by informal onsite interviews. The findings indicate significant variations in the use and accessibility of active transport in each neighborhood type for non-work trips. This suggests that each neighborhood type may need different strategies for promoting active transport: (1) the traditional mixed-use neighborhoods are in need of intensified urban retrofitting projects to reclaim public open space; (2) the work-unit could benefit from comprehensive plans rather than a patchwork of projects; (3) while opening up gated communities can improve porosity across neighborhoods and promote active transport, the more pressing issue may be their inability to keep up with the transportation needs of the residents; and (4) residents of resettlement housing should have better access to employment using transit and non-motorized modes.     

Does green transportation promote accessibility for equity in medium-size U.S. cites?

The link between accessibility and social equity attracts much attention for promoting sustainability. However, there is no comprehensive approach to elevate the role of accessibility in evaluating transportation system over social equity by considering the variety of urban opportunities and population groups from green transportation perspective. Our goal is to develop such a framework to evaluate transportation equity by focusing on accessibility via transit and cycling. Applying the framework to Fresno, California, and Cincinnati, Ohio with different development patterns, we delineate service areas at block-group level with five time-thresholds. The service area is used to count the number of urban opportunities: jobs, dining, churches, libraries, parks, multi-use paths, schools. We then use statistical comparison and geographical mapping to identify accessibility gap to these opportunities between advantaged and disadvantaged groups defined by income, property value, education, vehicle ownership, race, and age. The results indicate the extent of differences in accessibility is sensitive to threshold specification of grouping population. The findings suggest that the efficiency of transit service needs to be improved to reach the same level of cycling, while they do help with the accessibility for economically disadvantaged neighborhoods. Considering school enrollment, the accessibility to opportunities in Fresno performs differently while students in Cincinnati benefit from good accessibility to most resources. The results of accessibility to multi-use paths highlight the need of providing more efficient green transportation facilities for less wealthy neighborhoods. Variation in accessibility between groups underscores the importance of developing policies to meet the needs of diverse social groups.     

Evaluating a concept design of a crowd-sourced ‘mashup’ providing ease-of-access information for people with limited mobility

This study investigates the impact of using a concept map-based ‘mashup’ (www.accessadvisr.net) to provide volunteered (i.e. user contributed) ease of access information to travellers with limited mobility. A scenario-based user trial, centred around journey planning, was undertaken with 20 participants, divided equally between (1) those who have physical restrictions on their mobility, due to disability, illness or injury, and (2) those with practical mobility constraints due to being parents with young children who have to use a child’s pushchair when using public transport. Both user groups found the concept useful, but its potential impact was less for the pushchair user group. There were mixed views in relation to the ability of the mashup to convey the trustworthiness, credibility and reliability of information necessary for journey planning. The study identified a number of key information-related user requirements which help enable effective design of user contributed web-based resources for travellers with mobility-related issues.     

The mobility and accessibility expectations of seniors in an aging population

Populations of post-industrial nations are aging. With a growing number of people living well into their 80s and maintaining active lives, the transportation system will have to start focussing more closely on understanding their mobility and accessibility needs, so as to ensure that specific requirements of this large segment are not being ignored through the promotion of traditional ‘solutions’ and historical assumptions. This paper takes a close look at the evidence on the mobility needs and travel patterns of individuals over 64, distinguishing between the “young” elderly (aged 65–75 years) and the “old” elderly (over 75 years). This distinction is particularly useful in recognising the threshold of health change that impacts in a non-marginal way on mobility needs. This distinction also focuses transport planning and policy on a commitment to understanding the different needs of these sub-groups of the population, identifying services and facilities that better cater for these groups. We review the evidence, in particular, on the mobility characteristics of the over 75 years age group, including how they secure support through migration and settlement patterns. We use the empirical evidence from a number of western nations to identify the role of conventional and specialised public transport as an alternative to the automobile in meeting mobility and accessibility needs.     

Feasible provision of targeted traveler information in public transportation: Segmentation based on functional limitations

This paper presents findings on the need for traveler information among people with functional limitation(s), and how the need varies between groups with different functional limitation(s). Chi-Squared Automatic Identification Detector (CHAID) was used to identify groups (segments) in order to understand how functional limitations contribute to the need for traveler information. The key findings suggest that people with functional limitations have a greater need for traveler information concerning different aspects of travel beyond traveler information that relates to their functional limitation(s); this greater need also relates to groups of people with covert functional limitations to which little consideration is usually given. Further, it is feasible to consider the need of traveler information generated by functional limitation(s) in providing traveler information in public transportation, and people with combinations of functional limitations that include loss of lower extremity skills and prevalence of poor balance are particularly in need of relevant traveler information.     

Improving the accessibility of urban transportation networks for people with disabilities

What is the most effective way to enhance the accessibility of our oldest and largest public transportation systems for people with reduced mobility? The intersection of limits to government support with the growing mobility needs of the elderly and of people with disabilities calls for the development of tools that enable us to better prioritise investment in those areas that would deliver the greatest benefits to travellers. In principle and, to a lesser extent, in practice, many trains and buses are already accessible to nearly all users, leaving the stations and interchanges as the single largest and most expensive challenge facing operators trying to improve overall access to the network.Focussing on travel time and interchange differences, we present a method that uses network science and spatio-temporal analysis to rank stations in a way that minimises the divergence between accessible and non-accessible routes. Taking London as case study, we show that 50% of the most frequently followed journeys become 50% longer when wheelchair accessibility becomes a constraint. Prioritising accessibility upgrades using our network approach yields a total travel time that is more than 8 times better than a solution based on random choice, and 30% more effective than a solution that seeks solely to minimise the number of interchanges facing those with mobility constraints. These results highlight the potential for the analysis of ‘smart card’ data to enable network operators to obtain maximum value from their infrastructure investments in support of expanded access to all users.     

Incorporating equity into the transit frequency-setting problem

This paper and the proposed formulation contribute to an apparent gap in transit research design by integrating equity considerations into the transit frequency-setting problem. The proposed approach provides a means to design transit service such that equitable access to basic amenities (e.g., employment, supermarkets, medical services) is provided for low-income populations or disadvantaged populations. The overarching purpose is to improve access via transit to basic amenities to: (1) reduce the disproportionate burden faced by transit dependent populations; and (2) create a more feasible transportation option for low-income households as an opportunity to increase financial security by reducing dependence on personal autos. The formulation is applied to data from a mid-sized US metropolitan area. The example application illustrates the formulation successfully increases access to employment opportunities for residents in areas with high percentages of low-income persons, as well as demonstrates the importance of considering uncertainty in the locations of populations and employment.