| Co-Investigator(Kenkyū-buntansha) |
MORIKAWA Takayuki Nagoya University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30166392)
FUKUYAMA Kei Tottori University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30273882)
KITA Hideyuki Tottori University, Faculty of Engineering, Professor, 工学部, 教授 (50135521)
HOSOYA Ryouko Tottori University, Faculty of Engineering, Research Associate, 工学部, 助手 (40294342)
TANIMOTO Keishi Tottori University, Faculty of Engineering, Research Associate, 工学部, 助手 (20304199)
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| Research Abstract |
The aim of this study is to explore the future direction for efficient transportation systems supported by adequate modal coordination, by crossing over the recent researchers on the modal coordination in intercity transportation in California and Japan.
Under the growing socio-economic activities and the progress of transportation technologies, the needs for transportation services has become higher, and must be still high in the future. Transportation system have been developed continuously to satisfy these needs such as shorter travel time, lower travel cost, much more convenience, and less environmental impacts. Intensive investment on the development of most efficient transportation mode is essential to meet these needs. The efficiency of modes in transportation highly depends on the geographic, economic, and social conditions of the region. Therefore, the most efficient mode is not necessarily same in regions. The selected best-fit mode in each region has grown until now, and has
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become a dominant mode which characterize the transportation systems in the region.
Each region has some transportation problem such as road congestion, airport noise, or difficulty to maintain minimum service due to small demand. Sometimes, there exists a limit to meet these problems by making some improvement only on the mode. In such a case, coordinating different modes may be a solution to overcome it under the limited resources and/or environmental restrictions. The so-called "Intermodalism" policy is an expression of it. The major idea of this policy is to provide a rich variety of transport alternatives through a modal competition by raising up the connectivity, coordination, and cooperation between modes. Competitive market carries efficient results in general. However, it is also a well known fact that entrusting only the market mechanism does not always realize the best condition.
Generally, the marginal cost to provide an additional transportation service for newly increased demand is lowest in case of expanding dominant transportation mode than the case of developing minor mode, because of the economy of scale. However, in some cases, such an expansion becomes less efficient rather than expanding minor mode. Congestion at an airport which has no room for expansion is one of the cases. To switch a part of additional demand over another mode may be more efficient by expanding the mode if it is possible within a reasonable cost. A monopoly-like condition, where the most of transportation service is provided by a single mode, lacks flexibility and may carry an inefficiency in the long run.
To avoid such an inefficiency, it is important to organize multi-modal transportation system by coordinating transportation modes in their development and use from a view point of long-range planning. For making it possible, we must clarify many thing s including the image of socially optimized transportation system with modal coordination, the full cost of transportation services, the evolution process of transportation systems, and the behavior of users and transportation companies.
In this study, a comparative study on the transportation systems with different modal structures has been conducted to provide useful information for more effective transportation systems. California and Japan have many common conditions, while on the other hand many different conditions including the structure of modal share in transportation. By making comparison between the transportation systems and the surrounding conditions in both the countries, we explore the subjects mentioned above, especially, theoretical analyses on pathdependency and inefficiency of modal share, intercity travel time comparison, full cost comparison, and others. Less
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