Studies have already been published on the probability of collision at sea, the effect of darkness and reduced visibility on the probability of collision, and on the distribution of collisions in particular areas. Only Minorsky and Comstock appear to have studied the extent of the resulting damage and sufficient data are not available for detailed analysis.

The establishment and operation of any traffic management system calls for a considerable outlay, so that an objective estimate of the extent of collision losses is often required. Such a cost/benefit survey was carried out by the Japan Transport Economics Research Centre on the assumption that a traffic management system can greatly reduce the incidence of collisions involving vessels of over 3000 g.r.t. Since half the aggregate loss is shown to relate to these large vessels (and considering their increasing capital value), an expenditure of ten billion yen or more (£20 million) over a period of ten years would appear to be cost effective if its primary purpose were to avert accidents to large vessels.