Grounding hazard considerations in evaluation of COLREGS collision avoidance algorithms

Automatic evaluation of collision avoidance behavior with regards to safety and compliance with the International Regulations for Preventing Collisions at Sea (COLREGS) is a useful tool for developing safe and reliable collision avoidance algorithms, and a necessary component of any simulation-based verification scheme. As collision avoidance methods become more advanced, and capable of performing well in waters with restricted maneuvering space, accurate assessments of vessel behavior must also consider such restrictions. This paper presents methods for including considerations of the effect of grounding hazards on vessel behavior into an existing evaluation framework, originally developed for encounters in open waters. Encounters between vessels in normal operation, extracted from automatic identification system (AIS) data, are used to validate the evaluation methods. The validation is performed through employing both the original method and the extended method on each encounter. Selected scores and penalties from each method are then compared in order to display the effect of compensations given due to grounding hazards. The results show that grounding hazards preventing COLREGS compliant behavior does lead to compensation being given, also that the size of the compensation corresponds to the restrictiveness of the hazard.