Reconstruction on the change of main road system in Japan

1) The first main road system in Japan as an artery of the land was made up by the ancient government between mid 7.and early 8.century. This system was drastically transformed at the turn of the 8.and 9.century, namely around the making of Heiankyo. One of the reasons of this transformattion was the move of capital from Nara Basin to the northern part of Kyoto Basin. The other reason was that the policy of main road system by the government changed (decrease of posts and highways). K.Ashikaga, A.Kinda, and K.Kanasaka investigated this problem for the research area of Kanto Plain, Nankaido, and Hokurikudo respectively. 2) The system of straight road plan in ancient Japan experienced a large scale transformation between medieval and early modern ages due to two reasons : one is the inability of sustainable road maintenance, the other is the necessity for worrier's power together with its ability to realize it. Ashikaga clarified the actual condition of road system transformation by examining of the disappear of Hosshoji Oji and the move of Tosando in Koto Plain (to be published). 3) As for the problem of main road system in contemporary Japan, Narita showed that the opening of the express ways in Chugoku Area did not necessarily realized the desirable relationship of division and cooperation of work among cities along these express ways. Toyoda studied the economic effect of Seto Bridge for Shikoku and showed the interrelation between main road system and regional change. Finally, Ishikawa forecasted the future main road system change from the viewpoint of 'time-space convergence' concept.