ABSTRACT
In Korea, it is inevitable for tunnel to be generated following the construction of roads because more than 70% of land is mountainous area in view of topography features. It is actually tremendous national loss, i.e. cut-off of traffic and loss of lives due to collapses of Tunnel portal slope and entrance/exit slopes every year. The total number of tunnels, which are managed by nationwide 18 national highway maintenance & construction offices, are 105 tunnels, and the dispersion status of 5 regional construction management offices is as shown in Table 1. It was surveyed that there were many number of tunnels in Seoul Regional Office, Busan Regional Office, and Daejon Regional Office, and the average extension was resolutely the longest in case of Daejon Regional Office.
