The distribution of ship collisions in Japan is investigated and a method for estimating the number of collisions in harbours and straits is proposed, making use of maps of collision locations and the results of traffic surveys.

There are two major sources of information on marine casualties in Japan: the Report on Marine Casualty Statistics, made by the Ministry of Transport, and Report on Casualties Requiring Rescue, made by the Maritime Safety Agency. The former is based on the compulsory reports from either ship operators or owners, and casualties to foreign vessels are not included. A bibliography of collisions in the vicinity of Japan was made by taking the original report cards, overlapping data being carefully analysed.