Measuring Traffic Conflict of Single Ship Crossing Ship Flow Based on Integrative Distance Index

To supervise the traffic risk of single ship crossing ship flow in waters, an integrative distance index was proposed to measure the traffic conflict of single ship crossing ship flow by considering the impact of single ship crossing's dynamic course and associated multi-objects. A primary model was built to measure the traffic conflict of single ship crossing ship flow according to the inverse ratio relation between the integrative distance index and traffic conflict. Then, the criteria in mild, moderate, and severe traffic conflict conditions for single ship crossing ship flow were confirmed by comparison between the criterion from 85 percentile cumulated frequency value analysis based on expert questionnaire data and the probability interval at 95% of the observed integrative distance index data in corresponding conditions. The results show that measuring model can exactly reflect the impact of the three parameters of integrative distance index on the traffic conflict of single ship crossing ship flow. When the value of the three parameters increases simultaneously, the traffic conflict borne by single ship decreases; when the value of anyone parameter decreases, however, the traffic conflict borne by single ship increases. The criteria proposed in this paper applies to cases when visibility is 0.8 to 6.0 n mile in the inner waters, ship length is 60 to 180 m, ship speed is 3 to 13 kn, and the impacts of wind, current and wave are negligible.