International Journal of Sustainable Transportation最新文献

Taking the Yangtze River Delta (YRD) of China as the research area, this paper studies the influence of freight structure adjustment and energy intensity on carbon dioxide (CO2) emission from the transportation industry. Sample data from 1990 to 2019 are selected, and co-integration analysis is performed using three independent variables: energy intensity, turnover ratio of railway to highway (R/H), and turnover ratio of railway to waterway (R/W). Then, an autoregressive distribution lag-error correction model (ARDL-ECM) is established to estimate the long-run and short-run relationships among the variables through unit root test, autoregressive distributed lag (ARDL) boundary test, and Granger test. The results show that in the long run, the growth of energy intensity leads to the long-term growth of CO2 emission in the transportation sector of the YRD, and R/W and R/H have a suppressive effect on CO2 emission. Granger causality indicates that there is a bidirectional causal relationship between energy intensity and CO2 emission. This work can be a reference for government departments to formulate policies related to carbon emissions in the transportation industry.

Low-income populations are disadvantaged in a car-dependent society despite car ownership and could be using walking and cycling to reduce their travel costs. This study explores how low-income households with and without cars living in various geographies disproportionately use walking and cycling to save money in comparison to higher-income households. Data from the 2017 National Household Travel Survey is used to investigate the variation in walking and cycling behavior among three groups of households: (1) carless low-income households, (2) low-income households with cars, and (3) higher-income households. Generalized ordered logistic regression models are estimated to examine how the probability of using active travel to save money varies by household type, location (urban, suburban, rural) and other socioeconomic attributes. We find that low-income households are more likely to walk or cycle to save money on transportation compared to higher-income households. Carless low-income households present a higher probability to use active travel to decrease travel costs in comparison to car-owning low-income households. Our results also indicate that on average, urban residents are more likely to travel actively to reduce expenses compared to suburban and rural residents. The lowest spatial variation is found for carless low-income households, demonstrating their higher disadvantage compared to those with cars. Low-income people of color are more likely to use active travel to save money while being a female, older, or having children are attributes associated with a lower probability to use active travel to reduce travel expenses in low-income households.

Increasing greenhouse gas emissions from the conventional fleet of diesel buses has made Canadian transit agencies explore low-emission alternative fuels. Despite electric buses showing great potential to reduce emissions during their operational phase, the transformation from diesel buses to electric buses would require in-depth analysis pertaining to their economic and social implications. Published literature highlights the importance of developing a comprehensive framework that considers multiple decision parameters over a life cycle perspective for analyzing different fuel options to replace the existing fleet of diesel buses. This paper assesses the triple-bottom-line sustainability of diesel and electric buses in different regions of Canada. Moreover, a framework is proposed to incorporate multiple decision criteria (life cycle environmental, economic, and social impacts) over different perspectives to make the best decisions for transitioning the diesel bus fleet. The results showed that the environmental performance of electric buses highly depended on the electricity grid mix. Despite diesel buses having a low cost of production compared to electric buses, most provinces showed a low life cycle operational cost for electric buses. Electric buses’ life cycle social impacts are high during their production stage, whereas diesel buses have the highest social impacts during their operational phase. Overall, electric buses have a high sustainability performance in all provinces and territories in Canada except Nunavut. The proposed framework and findings can aid policymakers and planners in implementing electric buses for public transit systems in Canada and beyond.

While much of the bikeshare boom has centered around larger cities, smaller, lower-density, and even some rural communities have also implemented bikeshare systems successfully. Using a bikeshare dataset of more than 14,000 trips that cover the period from July 2018 to December 2021 for both pedal and e-bikes, this paper describes the structure and performance of ROAM NRV, a bikeshare system in Montgomery County, Virginia—which is home to Virginia Tech university and has many areas classified as rural. The paper presents bikeshare users’ travel behaviors and usage trends (including during the COVID-19 pandemic). Moreover, compares the usage of the system’s pedal bicycles to electric bicycles (e-bikes) that were introduced in 2021. Findings indicated that residents of Blacksburg and Christiansburg regularly use and benefit from bikeshare much like their urban counterparts do. Ridership was noted to likely be more common among university affiliates with trips more likely to start/end on or around campus due to the number of stations located within campus grounds. Trail usage was also high among bikeshare users due to the extensive trail network within and between the towns. As rural bikeshare users tend to travel greater distances and encounter more varying terrains throughout their commutes, considering e-bikes instead of pedal bike systems should increase the utilization of such mobility systems in rural areas. When electric assist bicycles were first introduced to the system, initially replacing some and then all former pedal bicycles, utilization increased significantly compared to pedal bike usage.

Numerous studies have explored associations between bicycle network characteristics and bicycle ridership. However, the majority of these studies have been conducted in inner metropolitan regions and as such, there is limited knowledge on how various characteristics of bicycle networks relate to bicycle trips within and across entire metropolitan regions, and how the size and composition of study regions impact on the association between bicycle network characteristics and bicycle ridership. We conducted a retrospective analysis of household travel survey data and bicycle infrastructure in the Greater Melbourne region, Australia. Seven network metrics were calculated (length of the bicycle network, betweenness centrality, degree centrality, network density, network coverage, intersection density and average weighted slope) and Bayesian spatial models were used to explore associations between these network characteristics and bicycle ridership. We demonstrated that bicycle ridership was associated with several network characteristics, and that these characteristics varied according to the outcome (count of the number of trips made by bike or the proportion of trips made by bike) and the size and characteristics of the study region. These findings challenge the utility of approaches based on spatially modeling network characteristics and bicycle ridership when informing the monitoring and evaluation of bicycle networks. Further efforts are required to be able to quantify network characteristics that reflect the myriad of factors that influence comfort and safety for people of all ages and abilities.

Shared mobility has brought many disruptive changes to urban transportation systems all over the world. Shared bikes have proven to be among the most successful and influential travel tools in attempting to alleviate the last-mile problem – the difficulty in getting people from transportation stations to their final destinations. This study aims to investigate the impacts of built environment factors on bike-sharing trips. Although many studies have explored these impacts, most have focused on the impacts of urban function, and have paid insufficient attention to the cycling environment. This study used multi-source data, including street view images (SVIs), points of interest (POIs), digital elevation models (DEMs), and road networks, to fully identify the influences of the built environment from five dimensions. The multiscale geographically weighted regression (MGWR) method was used to investigate the impacts of the urban built environment on bike-sharing usage. The results found that high-density roads, recreational POIs, and residential POIs all had positive impacts on the volume of bike-sharing trips in residential areas on weekends, whereas urban greenness negatively impacts bike-sharing usage in parks, because of strict regulations promulgated by local governments. Moreover, the impacts of high-density street networks and residential communities had strong spatial non-stationarity, while the influences of other built environment factors, including road gradient, eye-level greenness, and urban function mixture, were demonstrated spatial stationarity. These findings can facilitate local governments’ and enterprises’ efforts to improve the cycling environment and ensure the efficient management of shared bikes.

Addressing the need for curbing private motorization and car dependency while reducing inequalities associated with transport requires an in-depth understanding of the individual and collective practices, attitudes, and experiences of urban accessibility and mobility of populations across diverse socio-economic backgrounds. This paper builds on qualitative research methods and a framework of transitions to sustainable mobility to examine the links between travel needs, preferences, attitudes, and structural factors such as urban form, poverty, and informality at different scales. It proposes qualitative methods and evidence for accessibility-centred analysis to enrich policy and practice in cities across Sub-Saharan Africa (SSA), using Sierra Leone’s capital, Freetown, as a case study. While the volume of literature on urban mobility, accessibility, and land-use in SSA is increasing, scholarship on cities in Western Africa remains limited. The study examines four neighborhoods with different levels of access and motorization. It interrogates participants’ perceived accessibility, how they shape differentiated everyday mobility and land-use practices at the individual and collective level, and its implications for urban accessibility and sustainable mobility in the medium to long-term future. We found that perceived accessibility influences everyday mobility and land-use practices and the attitudes of individuals in diverse communities toward sustainable mobility by driving them to trade off immediate needs with long-term risks and exposures, imaginaries of motorized futures, as well as collectively transform the functional and physical configurations of the built environment to address their most critical needs in the absence of suitable top-down transport and land-use interventions.

The concept of Urban Air Mobility (UAM), an on-demand aviation service using air vehicles for urban short-distance trips, such as electric vertical takeoff and landing aircraft (eVTOL), has recently drawn public attention as one of possible solutions to traffic congestion in metropolitan areas. We present an optimal planning framework for fleet size and vertiport numbers using generalized cost models of UAM trip chains with two different ground access modes for first and last mile trips, including taxis and robotaxis (i.e. autonomous taxis or shared autonomous vehicles). As it is a relatively new and untested mode of transportation, our research aims to provide a decision-making tool for initial UAM system planning and analysis of its economic feasibility, appropriately considering its unique characteristics, such as high free-flow speed, low circuity, needs for ground access, and specific cost factors, such as vertiport and electric vertical takeoff and landing aircraft costs. Through a parametric study, we quantitatively examine the necessary conditions for UAM, with or without ridesharing, to become more economically viable than other ground-only modes. The study confirms that UAM can have potential economic benefits especially in large cities with longer average trip lengths and severe traffic congestion, where the average ground vehicle speed is low.

Numerous studies estimating transport CO₂ emissions in developing countries were on the large scales and few provided high-resolution mapping of transport CO₂ emissions from different transport modes according to their respective distribution and diffusion patterns. This study proposed a hybrid method for high-resolution mapping of transport CO₂ emissions in metropolitan regions, and applied it to the Beijing–Tianjin–Hebei (BTH) region of China during 2000-2019. The results indicate that: (1) The transport CO₂ emissions in the BTH region increased rapidly, of which road transport carbon emissions accounting for approximately 80%, air transport carbon emissions accounting for nearly 20%, railway and water transport accounted for a relatively small proportion. (2) For the transport CO₂ emission structure from 2000 to 2019, road transport was still the main source, but its proportion has decreased since recent years, which air transport became the second largest source of emissions and had greater impact on Beijing and Tianjin. (3) The transport carbon emission hot spots were mainly located in Beijing and kept shrinking, while the cold spots were mainly located in the southern part of Hebei Province and kept expanding. (4) The decoupling relationship between county-level transport carbon emissions and economic growth changed from weak decoupling to expansive negative decoupling, showing a non-ideal development in the BTH region. Overall, this study revealed the spatiotemporal characteristics of transport CO₂ emissions in the BTH region, based on which specific carbon reduction strategies could be promoted to facilitate sustainable low-carbon transport development in metropolitan regions in developing countries.

This article analyses actor relationships in Transit Oriented Development (TOD) planning in order to better understand the preconditions necessary for planning processes to result in TOD in lower density contexts, in suburbs, or small cities. Empirically, the analysis builds on a comparative case study of TOD planning projects. The focus in the analytical work is on understanding how market conditions in lower density contexts influence the conditions for TOD planning projects, and how this feeds through to planning processes. The overall conclusion is that we should not expect that planning processes in small cities with low to medium densities of populations and activities differ much from those in more ‘classic’ highly urban TOD locations. Market conditions had an impact on planning processes, but once in the planning stage conditions for implementation depended more on the ability to handle competing interests and less on market conditions. In terms of policy recommendations, it is important for actors to develop a joint vision of the built environment of the site in question that channels organizations’ individual actions in a joint direction. The ability to achieve such a joint vision for the design of the site in question may be more important in small towns than in more ‘typical’ TOD contexts in denser urban areas. This is because all enablers need to work together in a positive way in such location – which may be marginal from a market point of view – for the development to be able to go ahead.