Discovering themes and trends in transportation research using topic modeling

Transportation research is a key area in both science and engineering. In this paper, we present an empirical analysis of 17,163 articles published in 22 leading transportation journals from 1990 to 2015. We apply a latent Dirichlet allocation (LDA) model on article abstracts to infer 50 key topics. We show that those characterized topics are both representative and meaningful, mostly corresponding to established sub-fields in transportation research. These identified fields reveal a research landscape for transportation. Based on the results of LDA, we quantify the similarity of journals and countries/regions in terms of their aggregated topic distributions. By measuring the variation of topic distributions over time, we find some general research trends, such as topics on sustainability, travel behavior and non-motorized mobility are becoming increasingly popular over time. We also carry out this temporal analysis for each journal, observing a high degree of consistency for most journals. However, some interesting anomaly, such as special issues on particular topics, are detected from temporal variation as well. By quantifying the temporal trends at the country/region level, we find that countries/regions display clearly distinguishable patterns, suggesting that research communities in different regions tend to focus on different sub-fields. Our results could benefit different parties in the academic community—including researchers, journal editors and funding agencies—in terms of identifying promising research topics/projects, seeking for candidate journals for a submission, and realigning focus for journal development.     

The transportation systems of Buenos Aires, Chicago and São Paulo: City centers, infrastructure and policy analysis

We compare the passenger transportation systems of Buenos Aires, Chicago and São Paulo. The selected cities represent distinctive combinations of land-use, infrastructure, and evolution of transport policy. Analysis is centered on accessibility to downtown areas, where transportation processes converge in an environment where space is scarce. In two of the three cities institutional arrays that legally establish unified decision making have shown little capacity to launch fare or physical coordination between modes. In two of the three cities the concentration of public transportation supply to historical downtowns has not been an attraction factor, and downtown uses have expanded to less accessible areas. Gentrification in Chicago is also another process showing that land use changes are related to many factors, transportation being only one of them, and not always a necessary one. In all three cases the use of railways, as a set of inherited infrastructures, has seen an increase whose magnitude suggests a link to modal reassignment due to increasing congestion. Scarcity of space in old downtown areas is being counteracted through more intense use, or through the expansion of vertical space for transportation operations.     

Evaluating parking reservation policy in urban areas: An environmental perspective

This paper investigates a parking reservation mechanism to reduce car cruising to find parking. To consider the benefits for drivers and parking facility providers, we charge drivers for making reservations in addition to parking fees, by introducing a reservation pricing model that makes reservation prices equivalent to the value of saved search time. By modeling the number of vacant spaces as a stochastic variable, and applying binomial pricing methods, parking reservation prices are obtained. Numerical examples based on the data for two parking facilities in Taiwan are given.     

The Smeed Report 50 years on: a role for the workplace parking levy?

Fifty years ago, Reuben Smeed chaired a study and produced a Report on the Economic and Technical Possibilities of Road Pricing. This report was to consider different methods of charging, including road pricing, to see if different pricing methods could reduce the problems associated with congestion as opposed to the traditional methods in place such as fuel tax. Since that time, various attempts have been made to introduce road pricing schemes but with only modest success so far. By contrast parking policies, a second-best alternative to road pricing, have been extensively used by local authorities as a means of managing congestion. The effectiveness of such policies, however, has been limited by an increase in the proportion of privately owned non-residential parking which is not under the control of local authorities. The aim of this paper is to present the results of an early-stage, post-implementation study of the Nottingham Workplace Parking Levy (WPL) – a measure that charges employers for the number of parking spaces they provide for their staff. Particular emphasis is placed on why a WPL was seen as being favourable compared to a road pricing alternative. The reason for this was that it could be introduced in a shorter time frame and at a lower cost, thus making it a lower risk option when compared with road pricing.     

Behavioural economics,travel behaviour and environmental-transport policy

The transport sector creates much environmental pressure. Many current policies aimed at reducing this pressure are not fully effective because the behavioural aspects of travellers are insufficiently recognised. Insights from behavioural economics can contribute to a better understanding of travel behaviour and choices, and the impact of these on policies. Nevertheless, few studies have examined this issue. We review these and provide a broader, more encompassing perspective on environmental policy focused on transport, and taking into account bounded rationality as well as social preferences.     

Fuel price elasticities in the U.S. combination trucking sector

This paper estimates fuel price elasticities of combination trucking operations in the United States between 1970 and 2012. We evaluate trucking operations in terms of vehicle miles traveled and fuel consumption for combination trucks. Our explanatory variables include measures of economic activity, energy prices, and indicator variables that account for important regulatory shifts and changes in data collection and reporting in national transportation datasets. Our results suggest that fuel price elasticities in the United States’ trucking sector have shifted from an elastic environment in the 1970s to a relatively inelastic environment today. We discuss the importance of these results for policymakers in light of new policies that aim to limit energy consumption and reduce greenhouse gas emissions from heavy-duty vehicles.     

Empirical distributions of vehicle use and fuel efficiency across space: Implications of asymmetry for measuring policy incidence

Concerns about local air pollution and climate change have prompted all levels of government to consider a variety of policies to reduce vehicle dependence and fuel consumption, as the transportation sector is one of the largest sources of local and global emissions. Because many of the policy options under consideration are market-based (e.g., gasoline tax, carbon tax), it is important to consider how the impacts would vary across space and affect different subpopulations. Evaluating incidence is relevant for both the expected costs and benefits of a particular policy, however detailed data on vehicle-miles traveled (VMT) and fuel consumption allowing for the distributions of these variables to be estimated at a fine geographic scale is rarely available. This paper uses a unique dataset with more than 20 million vehicles in California to derive estimates of VMT and fuel consumption in order to examine the spatial distribution of impacts for an increase in the price of gasoline as well as the consequences of using different statistics for policy evaluation. Results show that VMT and fuel consumption distributions are not symmetrically distributed and vary significantly within transportation planning regions. To understand the potential implications of this asymmetry, we do a back of the envelope comparison using the mean and mode of the VMT or fuel consumption distribution for policy analysis. We find that assuming a symmetric distribution can lead to a divergence of 20–40% from the estimates based on the empirical distribution. Our results, therefore, introduce caution in interpreting the incidence of policies targeting the transportation sector based on averages.     

新加坡陆路交通系统发展策略

在满足居民人口增长变化对城市和城市交通发展提出的需求同时,新加坡正面,临着提高城市环境宜居性的挑战。针对这一问题,从三方面阐述了今后10～15年内塑造新加坡道路交通系统的政策与发展策略：一是通过扩展轨道交通、提高公交网络的整合度、优先发展公共交通;二是利用公路收费等手段限制车辆拥有与使用;三是建设无障碍设施以满足弱势群体的需求,向低收入群体提供帮助。最后,介绍了新加坡在提倡以人为本,鼓励公众参与,打造获得公众支持的道路交通系统等方面已经进行的工作。     

芝加哥大都会地区货运政策与规划

随着芝加哥地区在全球化经济中的日趋活跃,现有货运政策和货运设施在应对随之剧增的货运需求时日见乏力。围绕“芝加哥大都会地区2020”编制的《芝加哥大都会地区货运规划——物资与运输》,从组织机构、政策制定、基础设施、资金筹措等方面分析货运系统发展的相关措施。最后,指出这一货运规划的特色在于,并不是简单地论述增加货运通道、拓展货运中心等内容,而是注重货运规划的综合性,倡导多方协调与合作。     

民营经济与振兴东北老工业基地

从加快民营经济发展的角度谈振兴东北老工业基地,通过对民营经济内涵和影响因素的分析,阐述了东北地区发展民营经济的必要性和特殊性。