Jobs-housing balance in an era of population decentralization: An analytical framework and a case study

Despite the well-established theoretical understanding on the benefits of compact cities to the attainment of sustainable transport goals, there has been a worldwide trend of population decentralization in cities. In this paper, an analytical framework, which can be applied to other cities to quantify the potential commuting travel savings and environmental benefits of different job policies in cities having different rates and patterns of population decentralization, is presented. A case study of Hong Kong in the 1992-2002 decade is used to illustrate the analytical framework. The findings suggest that a city’s population patterns did have significant implications on the commuting travel savings from alternative job relocation policies. With a dispersed population pattern, the expected environmental benefits from a job decentralization policy can be very substantial.     

Are commuting patterns a good indicator of urban spatial structure?

Commuting patterns can be recognized by examining urban spatial structure. The latter can also be identified through the investigation of the former. This paper examines how well commuting patterns reflect the corresponding urban spatial structure. For this purpose, locational variables for commuting trip origin and destination are derived and included in an adjusted gravity model. The sign and the magnitude of the coefficients of those variables are interpreted along with the associated urban spatial structure. For a more formal comparison, urban density functions are estimated. Commuting data from the Seoul Metropolitan Region in 1987, 1990, and 1995 are used for an empirical analysis. The result shows that the distribution of employment is consistent between the spatial structure projected from the commuting patterns and the urban density distribution, while the distribution of employed residents is not, suggesting that the latter case should be interpreted with more caution.     

Optimizing the aerodynamic efficiency of intermodal freight trains

We develop an aerodynamic loading assignment model for intermodal freight trains based on an integer-programming framework to help terminal managers make up more fuel-efficient trains. This is the first use of optimization modeling to address the aerodynamics and energy efficiency of railroad intermodal trains. Several recommendations regarding railway equipment use, operations, and policy are proposed to improve fuel-efficiency and reduce emissions from intermodal transportation. Analysis of one major railroad intermodal route reveals the potential to reduce fuel consumption by 15 million gallons per year with corresponding savings of $28,000,000. Greater benefits are possible through broader implementation of the model.     

Time use, travel behavior, and the rural-urban continuum: results from the Halifax STAR project

This paper considers variations in time-related aspects of travel behavior along the urban-rural continuum, using the four categories of inner city, suburbs, inner commuter belt (ICB), and outer commuter belt (OCB). It employs geo-coded and GPS-validated data from the STAR survey conducted in the county-sized regional municipality of Halifax, Nova Scotia. Many significant inter-zonal differences are identified, and most travel variables are characterized by progressive urban-to-rural gradients, with large differences between inner-city and outer-commuter values. A clear break between city and country is seldom evident, however. Inner-city residents make most trips, but have trips of shortest duration, and spend least time in travel. Residents of the commuter belts spend most time in travel, and have trips of longest duration. While long trips and much driving were expected in commuter zones, there are significantly fewer trips in the OCB, which we attribute to lack of need, lack of opportunities, and adjustments in discretionary behavior.     

Shortest path or anchor-based route choice: a large-scale empirical analysis of minicab routing in London

Understanding and modelling route choice behaviour is central to predicting the formation and propagation of urban road congestion. Yet within conventional literature disagreements persist around the nature of route choice behaviour, and how it should be modelled. In this paper, both the shortest path and anchor-based perspectives on route choice behaviour are explored through an empirical analysis of nearly 700,000 minicab routes across London, United Kingdom. In the first set of analyses, the degree of similarity between observed routes and possible shortest paths is established. Shortest paths demonstrate poor performance in predicting both observed route choice and characteristics. The second stage of analysis explores the influence of specific urban features, named anchors, in route choice. These analyses show that certain features attract more route choices than would be expected were individuals choosing route based on cost minimisation alone. Instead, the results indicate that major urban features form the basis of route choice planning – being selected disproportionately more often, and causing asymmetry in route choice volumes by direction of travel. At a finer scale, decisions made at minor road features are furthermore demonstrated to influence routing patterns. The results indicate a need to revisit the basis of how routes are modelled, shifting from the shortest path perspective to a mechanism structured around urban features. In concluding, the main trends are synthesised within an initial framework for route choice modelling, and presents potential extensions of this research.     

Improving the efficiency of metropolitan area transit by joint analysis of its multiple providers

Public transportation in a metropolitan area often is supplied by multiple types of transit. This paper develops and illustrates a DEA-based procedure for estimating: overall efficiency of an area’s public transportation; technical efficiencies of the individual transit types; effect of each type on overall efficiency; and efficiency of the allocation of resources among types and an algorithm for improving it. The paper concludes that the overall efficiency of an urban area’s public transportation can be validly estimated only if the technical efficiency of each major transport type and the efficiency in allocating resources among them are taken into consideration.     

Analyzing the effect of aviation infrastructure over aviation fuel consumption reduction

The purpose of this paper is to examine the effect of various aviation infrastructure dimensions over aviation fuel consumption reduction (AFCR) performance. This study is an effort that considers the role of dimensions collectively from all aspects belonging to aviation infrastructure. The relevance of dimensions and constructs for hypothesis development are based on extensive literature review. Exploratory factor analysis (EFA) and Confirmatory Factor Analysis (CFA) were performed in the consecutive purification processes. Also, hypothesis testing was conducted using Structural Equation Modeling (SEM). A customized questionnaire was developed for collecting data from both kinds of respondents: Aviation industry experts and academic experts. Out of 382 approaches through mail survey, a total of 194 valid responses were collected. Analysis of the results shows the positive and significant impact of various factors such as: airport design, airspace management and air traffic control over the aviation fuel consumption reduction. Maximum importance is adjudged on air traffic control (ATC) and airspace route flexibility. The results of this study will encourage airlines and airport development authorities to increase their insight over aviation infrastructure, also to perform deeper analysis and find out precise values for real life implications.     

The role of turboprops in China’s growing aviation system

The Chinese aviation system is in a period of rapid growth, with significant growth in second tier and emerging cities. Lower density cities could be well served by regional aircraft, either regional jets or turboprops, which offer different qualities and a different future for Chinese aviation. Turboprops offer a high level of fuel efficiency compared with regional jets which may improve the cost economics for carriers and reduce the air quality and climate impacts of a growing aviation system in a region where air quality and greenhouse gas emissions are a serious concern. However, regional jets are known for their superior quality of service and faster travel speeds. We begin with a spatial analysis of existing Chinese short-haul aviation networks and find that turboprops are deployed in limited number and are dispersed throughout the country. Their limited use, however, is not because of their cost economics. For the existing regional jet network we estimate the trade space of fuel and time for the replacement of regional jets with turboprops and find that all regional jet routes in China would generate savings if replaced with turboprops. We next establish future short-haul aviation routes between new and emerging airports and estimate the likelihood that a turboprop will be used. The finding that the most viable turboprop markets are spatially dispersed through the country validates considering turboprop investment at the state-level as a component of the established Chinese aviation sustainability initiative.     

Level of service: the politics of reconfiguring urban streets in San Francisco, CA

Intersection level of service (LOS) is a traffic engineering concept which measures how streets handle automobile traffic. It is widely used in transportation planning as an indicator of delay at intersections. The use of LOS is often criticized for its bias towards automobiles at the expense of bicycling, transit, and walking, and it complicates smart growth or compact development. In San Francisco, California, there is a political movement to eliminate the use of LOS in planning. But this movement has met significant obstacles and debate. In this paper I explore how the debate in San Francisco is unfolding and suggest implications for broader efforts to reconfigure urban streets and urban space in the United States and globally.     

Quantifying grade effects on vehicle fuel consumption for use in sustainable highway design

The paper develops an analytical formulation that quantifies the effect of vertical grade on vehicle fuel consumption and then illustrates the use of the developed procedure in the identification of the fuel efficient freeway layouts. Specifically, the Virginia Tech Comprehensive Power-based Fuel consumption Model (VT-CPFM) was used to develop the formulation and then applied using 2015's 10 most-sold vehicles in the U.S. and Europe to quantify the vertical grade effect on vehicle fuel consumption rates. An increase in fuel consumption of approximately 140% was found when the roadway grade increased from 0.5% to 6%. The proposed selection procedure uses Geographical Information System (GIS) applications in the design phase to evaluate possible freeway layouts. A multi-criteria analysis is performed to rank the feasible alternatives. The yearly fuel consumed by cars traveling on each feasible layout is then predicted and the alternatives are sorted in ascendingly. If the alternative selected by the multi-criteria analysis gives the least yearly fuel consumption, then that alternative should be constructed. If not, then the alternative that results in the least yearly fuel consumption should be re-evaluated with respect to the one selected by the multi-criteria analysis tool. The proposed procedure is validated using a real case study involving the construction of a new freeway in Cameroon. As much as a 12% difference in fuel consumption was found between the alternative with the least estimated yearly fuel consumption and that selected based on a multiple-criteria decision analysis.     

A spatial microsimulation approach for the analysis of commuter patterns: from individual to regional levels

The daily trip to work is ubiquitous, yet its characteristics differ widely from person to person and place to place. This is manifested in statistics on mode and distance of travel, which vary depending on a range of factors that operate at different scales. This heterogeneity is problematic for decision makers tasked with encouraging more sustainable commuter patterns. Numerical models, based on real commuting data, have great potential to aid the decision making process. However, we contend that new approaches are needed to advance knowledge about the social and geographical factors that relate to the diversity of commuter patterns, if policies targeted to specific individuals or places are to be effective. To this end, the paper presents a spatial microsimulation approach, which combines individual-level survey data with geographically aggregated census results to tackle the problem. This method overcomes the limitations imposed by the lack of available geocoded micro-data. Further, it allows a range of scales of analysis to be pursued in parallel and provides insights into both the types of area and individual that would benefit most from specific interventions.     

Introducing a transport carbon dioxide emissions vulnerability index for the Greater Dublin Area

Energy consumption and carbon dioxide emissions from the transport sector have continued to rise, adding to growing concerns about the environmental impacts caused by transport systems and related land-use patterns. The transport sector in Ireland is a significant fuel consumer, accounting for 36% (5771 kTOE3) of Ireland’s primary energy demand in 2007. The sector was responsible for 36% (17,014 kt5 CO₂) of Ireland’s energy-related CO₂ emissions, higher than any other sector. Energy use in the transport sector grew by 181% (6.3% per annum on average) between 1990 and 2007. A key characteristic that distinguishes energy use in transport is the almost total dependence on imported oil as a fuel – over 99%, EPA (2009).Given the levels and growth of energy demand in transport, there is a clear imperative for policymakers to develop and implement measures and programmes that maximise energy efficiency and renewable-energy penetration. In this paper we develop a transport carbon dioxide emissions vulnerability index, using the Census of Population of Ireland 2006 Place of Work – Census of Anonymised Records (POWCAR) Dataset. The transport carbon dioxide emissions vulnerability index will be developed for the Greater Dublin Area to represent spatially in terms of transport carbon emissions the regional differentiations in commuting distances and modal shares. The results of this research can then be used to assess the transport carbon dioxide emissions of future development plans and therefore allow greater transport sustainability to be achieved through improved design of the location and form of major new development.