Night navigation safety assessment of ships based on actual measurement of port light environment

As an important transportation hub connecting land and sea, the port has also experienced rapid expansion, with some ports expanding into inland areas. Various lights such as port construction lights, berth ship lighting, and terminal operation lighting form a cluttered background light, causing light pollution, affecting the recognizability of navigation lights, navigational aids and other navigation lights, and affecting the safety of ship navigation at night. In order to prevent accidents in the port waters and evaluate the safety of large ships at night, this article takes the lighting environment of Heng li Petrochemical berth in Chang Xing Island Port area of Dalian Port as an example, and quantitatively analyzes relevant factors through on-site measurement using optical principles, colorimetry, and visual ergonomics, focusing on the impact of navigational light recognizability, ship light recognizability, and crew visual ergonomics. The influence of complex background light in the port on the recognizability of navigation lights mainly changes the brightness contrast, and has little impact on the color contrast of navigation lights. The illumination of the crane on the terminal is strong, which will have a certain impact on the berthing operations of ships at night. When a ship leaves the port at night, the background light around the terminal does not affect the departure operation. Based on this mechanism analysis, regulatory measures to reduce the impact of background light on nighttime navigation safety are proposed from the aspects of background light control, port lighting environment optimization, and navigational light technical transformation.