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Measuring ship collision risk in a dense traffic environment

Huang Y., Van Gelder P. H. A. J. M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2019

Vol. 13. no. 4

737--744

Collision risk measurement is an essential topic for ship collision prevention. Many risk measures, i.e. DCPA/TCPA, etc., decouple the ship traffic into several pairs of ships and then evaluate the risk in each pair. This kind of measurement loses some information of the entire traffic and might include some biases in risk measurement, especially in multiple-ship scenarios. In this article, Imminent Collision Risk Assessment (ICRA) is extended, which formulates collision risk as a ratio of reachable maneuvers leading to a collision and all reachable maneuvers (velocities). Two groups of scenarios have been simulated to show the ICRA is suitable for assessing the collision risk in multiple-ship scenarios. Moreover, two improvements have been introduced: (1) a generalized velocity obstacle algorithm is introduced to collect the maneuvers leading to collisions, which considers ship dynamics; (2) the constraints of forces are considered in the formulation of reachable maneuvers. As a result, the proposed measurement helps one ship assess the risk of approaching obstacles which are difficult to avoid the collision in terms of own-ship’s dynamics and kinetic constraints.

Classifying Ship Encounters to Monitor Traffic Safety on the North Sea from AIS Data

Iperen W. H.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2015

Vol. 9, no. 1

51--58

In studies for the Dutch Ministry of Infrastructure and the Environment, MARIN has developed methods to classify ship encounters on the North Sea from AIS data. The methods use the Distance at Closest Point of Approach (DCPA), Time to Closest Point of Approach (TCPA), and an estimate of ship domains, to determine for each crossing, head-on, and overtaking encounter, whether these follow abnormal patterns. On august 1 2013, the route structure on the North Sea, was rearranged to improve safety and efficiency. The encounter classification methods were applied to two years of AIS data. Heat maps of encounters show how the junctions have shifted. For these junctions, the numbers of encounters were compared. This paper discusses the methods to classify encounters, and the results of the comparison of the route structures. The results show a decrease of the number of exceptional head-on and crossing encounters in the new route structure.