Railway Construction in Japan

Progress of construction technology Japan has a relatively small proportion of lowland, consisting mainly of alluvial coastal plains. Railway construction started in the early Meiji Era (1868–1912) and since the construction technology was still immature, the first lines were built in level coastal areas. The rails were laid mostly on earth structures such as embankments and cuttings. Many railway bridges over rivers were also built at that time. Gradually, with progress in tunnelling technology, railways were constructed connecting towns and cities previously isolated by mountains. The post-war period of rapid economic growth in the 1950s and 1960s saw problems in securing urban land for new railway construction. Moreover, the rapid spread of automobiles gave rise to severe city planning problems with more traffic congestion resulting in railway crossing accidents. To solve these problems, more urban railways were built on elevated sections. With advances in construction technology, especially shield tunnelling, many new railways are being constructed underground. In recent years it has become completely impossible to secure new land for railway construction in big cities, although railway demand is still increasing. Furthermore, it is even getting harder to plan construction of new railways underground because there are already so many buried structures, including underground railways. Therefore, the future will see a good deal of effort in developing new technologies for using deep underground space, as well as space above existing railways. Comparison of Shinkansen lines by structure First, this article looks at changes in Japanese railway technology by comparing past and current Shinkansen structures (Fig. 1). The Tokaido Shinkansen—the world’s first high-speed railway—is built with a large proportion of earth structures, such as embankments. This method was chosen to shorten the work term and cut construction costs. It was possible because maintenance costs were not so high in those days and no one expected that the shinkansen would operate on the tight schedule of today (about 5 minutes headway). The Sanyo Shinkansen, completed about 10 years later, runs mostly through mountainous districts. Consequently, more than 80% of its length is tunnels and bridges (including viaducts). Rising track maintenance costs due to labour costs, resulted in more use of concrete slab tracks. However, since concrete slab track laid on earth structures requires strict control of track bed deformation, the Tohoku Shinkansen and Joetsu Shinkansen, both completed in 1982, have few such sections. To minimize railway construction and maintenance costs, the Nagano-bound shinkansen, which opened on 1 October this year, uses several new techniques for laying concrete slab track on an earth structure that is not deformed under the train load.