Ryosuke Abe

Effect of Built Environment on Gasoline Consumption in a Developing Megacity: Evidence from the Jakarta, Indonesia, Metropolitan Area

This paper analyzes the effect of the built environment on household gasoline consumption with data collected from 948 households in the metropolitan area of Jakarta, Indonesia. A structural equations model is developed to explain household gasoline consumption with motorcycle and car ownership as mediating variables. The results show that a smaller residence lot size and shorter access time to the nearest bus stop significantly decrease gasoline consumption. The access time to the nearest bus stop does not have an indirect effect through the ownership of cars or motorcycles but has a direct effect on gasoline consumption. In addition, the distance to the nearest regional core affects gasoline consumption positively through motorcycle ownership but does not affect it directly. Population density and neighborhood accessibility have a less significant impact on gasoline consumption, a finding supported by previous studies of developing cities. The results also show that the effect of residential self-selection is less significant. Finally, the estimated model is used to compute the potential impact of urbanization on gasoline consumption.

Impact of major road supply on individual travel time expenditure: An Exploration using a 30-year variation of infrastructure and travel

This study estimates the impact of major road supply on individual travel time expenditures (TTEs) using data that cover 30-year variations in transportation infrastructure and travel behavior. The impacts of the supply of road and rail infrastructure are estimated with a data set that combines records of large-scale household travel surveys in the Tokyo metropolitan area conducted in 1978, 1988, 1998, and 2008. Linear and Tobit models of individual TTEs are estimated by following the behavior of birth cohorts over the 30-year period. The models incorporate the changes in transportation infrastructure, measured as lane kilometers of two levels of major road stock and vehicle kilometers of urban rail service. The results show significant negative effects of lane kilometers for higher-level and lower-level major roads on the TTEs for all travel purposes and for commuting, after controlling for socioeconomic backgrounds and generations of individuals. This study discusses that, in Tokyo, the estimated effect is more likely to reflect the effect of a major road network per se on individual TTEs than the (indirect) effect of major road supply on individual TTEs working through land development activities (i.e., induced car travel demand). For example, the caveat is that actual road investment decisions still need to consider the induced component of road traffic in addition to the (direct) effect that is estimated in this study.

Long-run studies of daily travel: methodological review and convergence of distance traveled per capita across cities

ABSTRACT The purpose of this paper is to review previous studies that have modelled daily travel using long-run variations of data (20 years or more), focusing on their theoretical (micro-founded) assumptions, and then to present a case study applying one of these assumptions. The review intends to clarify how these studies assume intergenerational differences in the (unobservable) mobility preferences of individuals, which determines how they describe the changes in the aggregate of individuals. This study shows that one group of studies describes these changes using changes in the behaviour of individuals representing all generations and by assuming their preferences over time. This assumption is useful, as it accommodates all types of data covering different periods, including the so-called aggregate data. This study also shows that the other study group describes them using the turnover of individuals of different generations, assuming that individuals born in different periods could have different preferences. This has been made possible by following birth cohorts over time using data from repeated surveys while enabling a focus on generation-specific characteristics in daily travel. Next, the case study provides an example of how most previous long-run studies on daily travel have employed theoretical assumptions. It applies the first assumption to examine a convergence hypothesis of distance travelled per capita across cities. This hypothesis is derived from the assumptions posed primarily on the production-side of a city’s transportation system, including diminishing returns under current transportation technologies. A linear regression model is employed to test the hypothesis with a city-level data set covering 39 developed cities in the world from 1960 to 2000. The results support the hypothesis, showing negative and statistically significant effects of per capita annual kilometres travelled on their subsequent average growth rates in every model with different sets of the control variables representing the surrounding conditions of the transportation network. The results of the case study suggest that current daily travel may be exhausting most of the quantitative potential of a city’s transportation network under the current technologies.

Study on Seafloor Mineral Processing for Mining of Seafloor Massive Sulfides

Seafloor Massive Sulfides (SMSs), which were formed by deposition of precipitates from hydrothermal fluids vented from seafloor, has been expected as one of unconventional mineral resources on deep seafloors in the oceans. The authors have proposed the concept of seafloor mineral processing for SMS mining, where valuable minerals contained in SMS ores are separated on seafloor while gangue minerals are disposed on seafloor in appropriate ways. To confirm the applicability of column flotation, which is one of conventional mineral processing methods, to seafloor mineral processing, the authors carried out experiments simulating column flotation under the pressure conditions corresponding to the water depths down to 1000m in maximum using ore samples containing copper, iron, zinc and lead. In the experiments, formation of fine bubbles suitable to flotation and overflow of froth layer were observed at high pressures. The contents of copper and zinc in the concentrates recovered in the experiments at 1MPa were higher than those in the feed ores while the contents of silicon and calcium in the concentrates were lower than those in the feed ores. These results suggest that column flotation would be applicable to seafloor mineral processing.Copyright