Safety challenges related to autonomous ships in mixed navigational environments

Digitalization and technological advancements have accelerated the development and emergence of autonomous and remotely controlled ships in the maritime transport sector. This type of vessels consists of highly intelligent and adaptive functionalities, equipped with a variety of external sensors and actuators to gain situation awareness, automated control and adaptive maneuvering for achieving more efficient and sustainable operations. There are, however, many safety and reliability assurance challenges in autonomous operational and navigation systems due to their complex, adaptive, and non-deterministic nature. The issue of a mixed navigational environment where conventionally manned, remotely controlled, and unmanned vessels are interacting at the same sea area can be considered as one of the major obstacles in adopting of autonomous ships. Vulnerabilities can increase due to the potential divergence of vessel state awareness between autonomous operational systems and humans in such situations. Little research to date has dealt with such safety issues that a mix of human-operated, remotely controlled, and autonomous vessels will bring. This study explores the potential safety challenges related to autonomous ship operations in a mixed navigational environment and discusses several possible ways to reduce the same issues related to the identified safety risks, while including a discussion for possible future practice and research interests in ship navigation.