In these years, many bridges which span the waterway are constructed. For example, Honshu-Shikoku Connecting Bridge was opened in 1988 and the Tokyo Bay Crossing Bridge-Tunnel is being constructed. In Denmark, the Great Belt Bridge-Tunnel is also being constructed. After 1980 serious collision accidents between ships and bridges were not occurred but the number of accidents was not decreased. From the analysis of the ship collision accidents, it is shown that one of the causes is related to the waterways passing through the bridges. In this paper author investigated about the safety of the factors consisting of the waterway near the bridge, such as straight way, horizontal clearance, turning angle, waterway crossing angle and so on. From these considerations he evaluated the safety of the waterway passing through the bridge and these evaluation was applied to the new constructed bridge from the view point of safety. As the result, it has been found that the several factors of the waterway passing through the bridge affect the accidents. Especially, it is noticeable that the probability of ship collision is increased in case the main span is less than 3 times the ship length and the straight way is less than 8 times the ship length.
