To reduce the number of collisions between ships, it is useful to estimate areas where collisions between ships are likely to occur. In recent years, many studies on the estimation have been conducted using Automatic Identification System (AIS) data, which makes it relatively easy to analyze ship movements. However, accidents involving non-AIS ships occur frequently, and thus their movements should be included to estimate the areas. In this study, we analyzed the movements of non-AIS ships in Tokyo Bay using data observed by radars, which are installed on shore around Tokyo Bay. Additionally, we estimated collision caution probability, which is one of the indexes representing the likelihood of a collision occurrence, for ships including non-AIS ships. The results were compared with the probability based only on AIS data and conventional estimates, and trends were clarified corresponding to current traffic situations.
