Backjin Lee

Urbanization and subsurface environmental issues: An attempt at DPSIR model application in Asian cities

This paper synthesizes existing information and knowledge on subsurface environments to understand the major cause and effect relationships of subsurface environmental issues by using the DPSIR (Driving force-Pressure-Status-Impact-Response) approach as the framework of analysis. Description is given to the major subsurface environmental issues common among the selected Asian cities (Bangkok, Jakarta, Manila, Osaka, Seoul, Taipei and Tokyo), such as excessive groundwater abstraction, land subsidence and groundwater contamination. The DPSIR framework is used to analyze the issues and problems of subsurface in key stages and suggestions are made for additional indicators to improve our description of the stages of urban development for the future.

Passenger Choice Models for Analysis of Impacts of Real-Time Bus Information on Crowdedness

This research explores the effect of bus occupancy information on transit users’ choice of a bus by use of a binary logit model. The model predicts the probability of bus choice between the first arriving bus and the second arriving bus. The analysis is based on interview survey data obtained over 1 week (June 19 to June 25, 2008) in the Seoul metropolitan area in South Korea. The data reveal that the need for public transportation information varies by user group (white- or blue-collar workers, students, homemakers, self-employed workers, and older people) and the stage of the trip (before a trip, at a stop, on board, and at a transfer point). The results show that the availability of seats will increase the probability that a bus user will choose to board an arriving bus, with all other things being kept constant, whereas the travel time on board and the crowded-ness on a bus decrease the probability that a public transit user will choose to board an arriving bus. The effects of bus occupancy information are also different among user groups (white- or blue-collar workers, students, homemakers, self-employed workers, and older people) and trip purpose (commute and noncommute).

Strategies to Promote Sustainable Mobility Management Incorporating Heterogeneity

ABSTRACT The objectives of this article are to suggest strategies for Mobility Management (MM), which has attracted increased attention as sustainable transportation policy, through incorporating heterogeneity in trip maker. The heterogeneity was analyzed by latent class model using psychological variables, segmented by three latent classes: (1) “Environmentalists with non-actively travel”; (2) “Environmentalists with actively travel”; and (3) “Non-environmentalists.” In addition, it could be demonstrated the transitional process in travel behavior for reducing car use by structure equation model, consists of three steps (attitude change → behavioral intention → actual action), and each step is influenced by psychological variables related to environmental awareness, attitudes toward public transportation, and auto preferences. Finally, to promote the MM effectively for sustainable transportation, some strategies were suggested considering the characteristics of trip makers.

Spatiotemporal Changes of Traffic Demand Price Elasticities in Japan Throughout 2008 Bayesian Approach

This study attempts to examine spatiotemporal changes of traffic demand elasticities regarding gasoline prices and economic conditions and focusing on the substantial fluctuations that occurred throughout 2008 in Japan. This research is aimed at a better understanding of the spatial and temporal instability of the elasticities and possible reasons for changes in the elasticities. First, a random coefficient model is built to represent spatial heterogeneity in the elasticities and is estimated by using a hierarchical Bayesian method. Next, a sequential Bayesian updating method is applied to examine monthly changes in the elasticities. The data used in the empirical analysis were monthly traffic volume data collected on 53 expressways. The results showed that although the monthly changes in the average elasticities over all routes were mainly observed before August 2008, different directions of change across routes were observed after September 2008, when gasoline prices began to fall. The results also indicated that responses to gasoline price changes might be dependent on the causes of price changes. Furthermore, on urban expressways, it was found that once a reduction in traffic demand was attained because of rising gasoline prices, the demand did not fully recover even after the actual prices fell again to the original level.