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This research reaffirms a sustainable transport investment should go forward in a way that enforces consistent economic growth while maintaining environmental benefit. Society's economic input-output relations reinvest the time saved by the transport system, of which benefit appeared as the income level's rise. This research empirically proves that the recursive profit is possible when the infrastructure aligns accessibility enhancement with industries' productivities. Specifically, we found that the interactions between industries and accessibilities make synergy when the industries maintain appropriate productivity. Under the same context, the measure for the socially vulnerable should start at capacity building even given transport, based on which we can build economically equitable accessibility. This research takes environmental sustainability granted as long as the incumbent Korean infrastructure investment principle exists without empirical analysis. A comparative analysis using structural equation models proved the existence of the synergy due to the accessibility-industry interactions. Besides, we captured the quantities of the synergy through groups of partial cross-sectional correlations. Authors conclude that government authority needs to pursue the best synergy between transport plan and economic development strategy, and prepare a capacity building for the socially vulnerable furthermore. [ABSTRACT FROM AUTHOR]

Cycling is gaining popularity both as a mode of travel in urban communities and as an alternative mode to private motorized vehicles due to its wide range of benefits (health, environmental, and economical). However, this change in modal share is not reflected in current transportation planning and travel demand forecasting modeling processes. The existing practices to model bicycle trips in a network are not sophisticated enough to describe the full cyclist experience in route decision-making. This is evident in the existing practices' methodology: the all-or-nothing assignment uses single attributes such as distance, safety, or a composite measure of safety multiplied by distance. The purpose of this article is to develop a multi-class and multi-criteria bicycle traffic assignment model that not only accounts for multiple user classes by acknowledging that there are different types of cyclists with varying levels of biking experience, but also for relevant factors that may affect each user classes behavior in route choice decisions. The multi-class, multi-criteria bicycle traffic assignment model is developed in a two-stage process. The first stage examines key criteria to generate the set of non-dominated (or efficient) routes for each user class, and the second stage determines the flow allocation to efficient routes by user class. Numerical experiments are then conducted to demonstrate the two-stage approach for the multi-class, multi-criteria bicycle traffic assignment model. [ABSTRACT FROM AUTHOR]

The acceleration profile of leading vehicles at intersections is critical for emission estimation and microlevel queue simulation. Data obtained from experiments using a high-resolution driving simulator can deliver useful insights into microscale acceleration behaviors at signalized intersections. Acceleration data of the leading vehicles in queues are collected by the simulator. The observed accelerations are found to be stochastic. The acceleration characteristics are also significantly diversified among participants. Hence, a Markov chain is implemented to simulate the acceleration behaviors. The acceleration data are classified into varied operation states. And the Markov chain reconstructs the acceleration profiles of leading vehicles and reproduces the randomness of acceleration behaviors. Among numerous candidate profiles, a speed profile is selected by a proposed criterion that represents the typical acceleration behaviors at signalized intersections. [ABSTRACT FROM AUTHOR]

Mobility as a Service (MaaS) is an innovative concept, enabled by the ubiquitous availability of digital technologies. Many cities around the world envision MaaS as a way to improve sustainable transportation by reducing the use of fossil fuel-based transportation modes. However, MaaS may also trigger users of environmentally-friendly transportation modes to switch to less sustainable modes, such as taxi and ridesharing. The aim of this study is to explore how different bundling and pricing schemes of MaaS contribute to improving sustainable transportation. In order to analyze individuals' intended choice of MaaS, a stated portfolio choice experiment was developed. A mixed logit model is estimated to investigate the bundle of transportation modes individuals configure when subscribing to MaaS. We explore empirical issues such as which transportation modes they prefer to include in the bundle, and how pricing schemes affect the composition of the bundle. Furthermore, scenario analyses are conducted to assess the impact of pricing schemes on sustainable transportation. Results show that MaaS contributes to improving sustainable transportation in a non-linear manner as a function of decreasing monthly subscription fees and/or increasing length of the subscription. [ABSTRACT FROM AUTHOR]

Although there are several policies for promoting green vehicles, green vehicles have yet to penetrate the market to the extent desired. To attain the goal, a complete understanding of consumers’ preferences of green vehicles is essential. This paper proposes and specifies the fuel-type choice models among conventional gasoline vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles by vehicle size using the stated preferences data collected in Seoul, Korea. The results highlight the need to accommodate the correlation between similar alternatives and the unobserved heterogeneity within the context of choosing a green vehicle. The choice probabilities of green vehicles are affected by the relative impacts of the vehicles’ attributes and socio-demographic variables, and both of these variables are affected by the sizes of the vehicles. For compact size and mid-size vehicles, the effects of operating costs were less than those of purchase prices; however, for the subcompact vehicles, the effects of operating cost were greater than those of purchase price. The parameter of operating costs was not statistically significant in the full-size model. With respect to electric vehicles, the availability of fuel stations would be more important in Seoul than in the U.S. These results can also be useful for policy makers in that they provide information about the impact of green vehicles’ attributes on the choice probabilities of green vehicles. [ABSTRACT FROM AUTHOR]

This study proposes an integrated simulation approach, which consists of a microscopic traffic simulation model, a vehicle dynamics model, and an emission estimation model, in order to estimate emissions based on more reliable vehicle performance measures. The vehicle performance measures such as engine power and engine speed significantly relate to the amount of emissions, and road curvatures and inclinations are the core inputs affecting these vehicle performance measures. Therefore, providing reliable vehicle performance measures reflecting the road geometric attributes is critical for a reliable emission estimation. This study proposes to use the microscopic traffic simulation model for generating vehicle trajectories, which is advantageous in modeling various traffic situations, and the vehicle dynamics model for producing the vehicle performance measures based on the vehicle trajectories. Finally, the outputs from the vehicle dynamics model are fed into the emission estimation model to compute emission measures. This study conducted a case-study using two road sections, one is a hypothesized road section, including various curvatures and inclinations with regular variations, and the other is a Kesselberg road section, which is an actual geometry in Bayern, Germany. The emission measures are estimated in these case-study road sections using both an existing simulation approach and the proposed integrated simulation approach. The difference between these two emission estimation approaches is discussed in terms of the emission measures, including fuel consumption, nitrogen oxides, and particulate matters. [ABSTRACT FROM PUBLISHER]

This study establishes a network data envelopment analysis (DEA) model to evaluate the sustainability of public transportation services targeting rapid routes for buses in the Seoul metropolitan area. A network DEA-based optimization model is formulated to evaluate the sustainability of the public transportation service. By considering public transportation services from both the operators’ and users’ perspectives, this model produces results that reflect the interaction of three sustainable transport service properties, i.e., efficiency, equity, and environmental impacts. It is identified that the expansion of median bus lanes and the conversion of conventional buses into compressed natural gas vehicles could improve the sustainability of the public transportation services in the Seoul metropolitan area. Some limitations and future research agenda also are presented. [ABSTRACT FROM PUBLISHER]

Electric vehicles (EVs) are energy efficient and often presented as a zero-emission transport mode to achieve long-term decarbonization visions in the transport sector. The implementation of a sustainable transportation environment through EV utilization, however, requires the addressing of certain cost and environmental concerns such as limited driving range and battery-charging issues before its full potential can be realized. Nevertheless, a specific type of use of EVs, namely in taxi services, may elicit positive public opinion, as it promises a commitment toward sustainability in urban life. In light of this, this study proposes an integrated approach that combines EV operation with a conceptual design for shared-ride taxi services. As some productivity loss may be naturally expected due to the time spent in charging, it is important to look at whether such performance loss from the passenger and system standpoints can be offset with ingenuity in operational design. In this study, an EV taxi charge-replenishing scheme that can be coupled with a real-time taxi-dispatch algorithm is designed. The proposed EV charging schemes for taxi services are studied via simulations and the effects of the limited driving range and battery-charging details are examined from a system performance viewpoint. The simulation study also reveals illustrative results on the impact of the EV taxi fleet's operation on the charging system. Next, a real-time shared-taxi operation scheme that allows ride sharing with other passengers is proposed to maximize the operational efficiency. The simulation results suggest that the shared-taxi concept can be a viable option to improve on the limitations caused by EV operation. In addition, the importance of projected charging demands and queue delays at different charging locations are also addressed. Some limitations and a future research agenda are also discussed. [ABSTRACT FROM AUTHOR]

Public transportation has been regarded as one of the most sustainable forms of transport, because of which local governments have put efforts in increasing the mode share of public transportation. Recently, not only level of service but also user satisfaction has been focused on for the assessment of transport policy; however, several points have been overlooked in previous research, such as attribute-based satisfaction, the relationship between level of service and satisfaction, and user expectation. This paper deals with these issues while assuming the heterogeneity of satisfaction, which is an indicator of perception. Out-of-vehicle times, particularly headway and access time, were selected in the analysis because they can affect travel behavior of current and potential public transportation customers. In this analysis, pattern-recognition models were applied, and public transportation users were segmented in terms of perception. The results suggest several notable recommendations for public transport policies and investigations. [ABSTRACT FROM AUTHOR]

Most walking travel behavior research thus far has tested area-based neighborhood walkability, which is measured with meso-level urban form attributes. In need of micro-level walkability analyses that focus on individual travelers and their routes, we propose a route-oriented linear walkability concept named “path walkability.” It is defined and measured by 42 path walkability indicators that can collectively represent an individual traveler's micro-level walkability. A graphic measurement instrument for an objective and efficient on-field walkability measurement is developed. This study also sets the protocol for quantitatively integrating the walkability data measured at the segment level into path walkability indicators that are comparable at the route level. To test the applicability of the proposed path walkability, a pilot case study is conducted within a station area. A user survey is administered to collect transit users' access mode choices and walking routes to the station. The survey results help identify two groups of street segments: one used by regular walkers and the other selected by habitual auto users/occasional walkers. The routes chosen by the two groups are quantitatively and graphically compared for walkability. The analyses show a physically measurable and quantitatively comparable difference between the routes' walkability and suggest criteria for walking-conducive transit walkability for station users. Specific design recommendations for improving street-level micro-walkability for future transit-oriented developments (TODs) are added along with a future research agenda. [ABSTRACT FROM AUTHOR]

Today, air pollution is a great issue, and the transport sector is an important emission source. In this study, we present an integrated land use, transport, and environment model in which transport-related pollutants are assumed to influence people's housing location choices, and a continuum modeling approach is applied. The pollutants generated by the transport sector are dispersed by the wind and they affect air quality. The air quality changes people's housing choices, which in turn changes their travel behavior. We assume that the road users are continuously distributed over the city, that the road network is relatively dense, and that this network can be approximated as a continuum. The total demand is categorized into several classes, and the modeled region contains several subdistricts. People who live in different subdistricts or who belong to different classes of commuters are assumed to have different perceptions of travel time, air quality, and the housing provision–demand relationship. The finite element method and the Newton–Raphson algorithm are adopted to solve this problem, and a numerical valuation is given to illustrate the effectiveness and efficiency of the proposed model. [ABSTRACT FROM PUBLISHER]

The public bike system (PBS) has been actively promoted worldwide for the last decade. This study tried to find out policy strategies for sustainable PBS implementation targeting on the city that is under consideration of introducing bike sharing scheme. For this, the authors considered some psychological factors that may make impacts on PBS user's attitudes and hypothesized especially that individual environmental concern refers to an attitude toward environmental issues, influence an increase of their perceived value of PBS. The Norm Activation Model (NAM) is used to measure the public's environmental concern incorporating norm activation. In addition, willingness to pay (WTP) method is adopted to investigate the value of PBS individuals. Structural equation modeling (SEM) revealed that environmental concern influenced people's perception of the value of PBS. Furthermore, the positive correlation between environmental concern and awareness of consequences on cycling is observed. The study verifies how people perceive the value of a bike sharing system and how often people using a bicycle are dependent on their environmental concern. In conclusion, authors discuss how PBS could be promoted sustainably by suggesting policy strategies to enhance the perceived value of PBS and to increase bicycle use. [ABSTRACT FROM AUTHOR]

In order to improve the effectiveness of transit-oriented development (TOD), the integration of public transportation and bikes has been regarded as a good alternative because the catchment area of a station, that is, the spatial extent of TOD, can be increased. This paper suggests the concept of bicycle-based TOD (B-TOD) and estimates the spatial extent, considering the catchment area. For this, a trip survey was conducted among bicycle users who used bicycle and public transportation in Seoul metropolitan and Daejeon metropolitan areas in Korea. Regression and cumulative distribution models were used to estimate the spatial extent of B-TOD. The results show that the estimated access distances were 1.96 km and 2.13 km for origin (home)-to-station and station-to-work trips, respectively, and they can play a yardstick role in the TOD planning practices in Korea. In such cases, the catchment areas of B-TOD cover 73.7% and 93.6% of the whole area of Seoul, whereas conventional walking-only TOD can cover only 29.9% of the same. This implies that B-TOD can help to solve one of the key inherent weaknesses of the conventional TOD. Some limitations and recommendations for future research are also discussed. [ABSTRACT FROM AUTHOR]

This article proposes a novel urban system equilibrium model for design of a tradable location tax credit scheme to balance traffic congestion and environmental externalities. In the proposed model, the interaction between the location tax credit scheme and households' residential location choices is explicitly considered. It is assumed that the authority initially allocates the credits to all households in a uniform way, and the households pay a certain amount of credits for housing consumptions, relying on the traffic congestion and environmental externalities that they cause. The credits are traded among households through a free market, and the tax revenue due to credit trading is considered as a part of household's income to be redistributed through household's income budget constraint. For a given credit scheme, households' residential location choices and housing market structure in terms of housing prices and space can be endogenously determined by the urban system equilibrium and the price per unit of credit is governed by the credit market equilibrium. A social welfare maximization model is presented to determine the total amount of credits issued. The results show that implementation of the tradable location tax credit scheme can rationalize the urban residential density and promote the efficiency of the urban system in terms of social welfare. [ABSTRACT FROM AUTHOR]

This article focuses on micro-level walkability, which is measured at the route level and thus named “path walkability,” and tests whether path walkability influences transit users' mode choices to the station. To test its impact on access mode choices, a case study is conducted in downtown Mountain View, California. A station user survey is administered to collect access mode choice, socioeconomic status, and trip origins and walking routes of 249 transit users with previous experience of walking to the station. Using a path walkability measurement instrument developed for this research, 38 path walkability indicators are extracted from each of the 249 walking routes. The 38 walkability indicators are grouped by using factor analysis yielding four path walkability factors: “sidewalk amenities,” “traffic impacts,” “street scale and enclosure,” and “landscaping elements.” The four factors are utilized as new walkability variables for modeling access mode choices. With 150 walkers and 99 habitual auto users/occasional walkers, two access mode choice models are estimated. The basic model is first estimated without walkability variables and then the four path walkability variables are introduced for the expanded model. All four path walkability variables enter the expanded model and significantly improve the predictability of the mode choice model. The model result suggests that micro-level walkability influences access mode choices in a statistically significant way and having more walking-conducive walkability available for access trips increases the chance of choosing walking over driving. This research shows that improving micro-level walkability could be a cost-beneficial incentive for more walking to the station. [ABSTRACT FROM PUBLISHER]

A nested logit model predicting the probabilities of commuters choosing three different modes were constructed to test the effect of the Seoul bus reform. Some empirical findings include the following. First, the Seoul BRT system contributed to increases in the patronage of bus over subway within the BRT catchment area (BCA). Second, commuters working in the BCA are more likely to choose to commute by bus than are people living in the BCA, which indicates that high accessibility to the BRT strongly influences workers who commute to their jobs to ride the bus. Third, percentage changes in the odds of choosing bus over subway were higher than those of choosing bus or subway over automobile for both BCAs, implying that the accessibility to the BRT contributed to inducing commuters to favor bus over subway. [ABSTRACT FROM AUTHOR]

With increasing concerns about environmental and energy issues in many large Chinese cities, local authorities are introducing public bicycle schemes to promote the use of green transportation modes. This paper proposes a novel model for investigating the effects of the public bicycle schemes in a congested multi-modal road network with auto, bus, and public bicycle travel. The decision-making process of travelers regarding travel modes and route choices is assumed to follow a hierarchical choice structure. The effects of pollution emissions by motorized vehicles (i.e., autos and buses), crowding discomfort in buses, and riding fatigue on bicycles are considered in the proposed model. The multi-modal travel choice equilibrium problem is formulated as an equivalent variational inequality problem. The existence and uniqueness of the solution of the proposed model are examined. A heuristic solution algorithm that combines a diagonalization approach and the method of successive averages is adapted to solve the proposed model. A numerical example is given to illustrate the application of the proposed model and solution algorithm. Findings are reported on the effects of the public bicycle schemes and emission tax policy on the multi-modal transportation system. The optimal public bicycle rental price and emission tax for maximization of social welfare can also be determined by the proposed model. [ABSTRACT FROM PUBLISHER]

Estimating long-term vehicle ownership and energy use is essential for national transportation planning, especially for addressing policies regarding climate change. In this paper, long-term vehicle ownership and energy use in Korea is estimated according to income and fuel price scenarios. A modified form of a quasi-logistic growth function is employed to consider the causalities between vehicle ownership and independent variables. Vehicle ownership has been identified to be more sensitive to income change than to fuel price expectations. The likely fuel price increase evaluated in this research would not deter people from buying cars. This implies that future transportation energy conservation policies should be based more on transportation demand management (TDM)–type policies. [ABSTRACT FROM PUBLISHER]

Minority status and low-income are two important criteria on which environmental-justice areas are being identified. These unique areal characteristics have been of particular interest to traffic safety analysts in investigating pedestrian safety planning factors in deprived areas. In this study, a pedestrian crash model was developed for these areas explicitly accounting for the spatial autocorrelations of different zonal factors commonly used in the traditional transportation planning models. It was found that the Bayesian Poisson-lognormal model with a spatial effect term performed the best compared to the models without accounting for spatial autocorrelations. [ABSTRACT FROM AUTHOR]