Towards Intercity Cooperation: Comparison of Spatial Transport Energy Efficiency Between Central and Peripheral Cities in Japan

Abstract

Interest in transport energy efficiency in a given spatial area has been increasingly growing as a research topic. Various studies have analyzed the overall association of energy-related indicators with the city form, whereas the compassion of individual city has yet to be fully evaluated. Given the importance of developing the efficient intercity transport cooperation, the consideration of intracity transport situation in the two relevant cities is necessary before determining the intercity travel mode among various modal choices. There is a possibility that even if the intercity public transport infrastructure is developed, automobiles would be the first choice for the intercity travel as long as the public transport system inside of the peripheral cities is not well developed. Therefore, a focus on differences of spatial transport energy efficiency between central and peripheral cities is of significant importance. In particular, the city combination in Japan would be an appropriate case study. In response to the decrease in population, networking the central city with peripheral cities to construct the coordination through the public transport is highly required in Japan to maintain quality of life and sustainable city management. This study first assesses the transport energy efficiency of various transportation modes in the form of transport energy intensity in Japan. The assessed transportation means include walks, bicycles, automobiles, buses and electric trains. The transport energy intensity is obtained on the basis of well-to-wheel (WTW) fuel consumption and energy input for the material structure. Then, this is integrated with the modal split to obtain the spatial transport energy intensity in a given city. This study focuses on 44 cities in Japan and evaluates its relationship with population. Finally, by using the hierarchical cluster analysis, its differences between central and peripheral cities in the major metropolitan area, the sub metropolitan areas and regional urban areas are evaluated from the perspective of the geographical location and city scale gap to assist in identifying the specific areas where limitations on constructing the coordination in future are imposed and in providing the strategy depending on the city categorization. It was found that transport energy intensity decreases in the order of automobiles, buses, electric trains, bicycles and walks and the energy input for the material structure significantly affects the transport energy intensity for the small-scale transportation means. In addition, the cities in Japan of lower spatial transport energy intensity were also those with greater population. This trend seen in the case of Japan is matched with the global trend which has been widely reported. In the major metropolitan areas, the spatial transport energy intensity in the peripheral city decreased with distance from the central city. Some peripheral cities more than 30 km away from central cities were identified as the most challenging city combination for constructing the coordination with respect to the spatial transport energy intensity.