In order to obtain a method for determining the ship domain applicable to restricted channel waters, this paper first introduces relevant theories of road traffic engineering and related parameters like ship speed, ship size, driver response time. Ship braking performance and dangerousness of ship's cargo factor is also addressed to build a ship-following model in restricted channel waters. The model is capable to obtain expressions of ship domain between one-way ships at different safety condition levels. Taking the arrival of two large ship formations in a certain port as an example, using the ship domain determination model proposed in this paper, the safe distance between the ship's entry and exit port is obtained. The case study verifies the soundness of the model and provides a theoretical basis for further research in restricted channel ship domain.
According to the analysis of ship data in recent years, the number of ships entering and leaving ports is increasing, and meanwhile the number of traffic accidents of ships in water channel is also increasing (Wen et al., 2015). Therefore, it is necessary to determine the safety clearance among ships to ensure the safe navigation. The safety clearance among ships greatly affects a port's throughput and the safety of ships. The safe distance between the entry and exit of a ship means the minimum distance between the one-way ships in case of ensuring the safe navigation of a ship and not affecting the smooth traffic of the channel. The spacing is closely related to the maneuverability, braking performance of a ship, the type of the ship, the hydrology and meteorological conditions of the channel.
There are various ways to express the safe spacing of ships in the channel, but the most frequently used are the spacing between the bows of ships before and after, the multiple of captain, etc. At present, the safe spacing of ships in different ports is different. Normally, the determination of safety clearance is mainly based on the meteorological and hydrological conditions of the navigation channel over the years and the characteristics of the arriving vessels. It can also be based on accumulated experience to determine the corresponding value. For example, the relevant maritime, port and shipping departments along the Yangtze River conducted statistical analysis according to the actual situation of the section in which they are located. Finally, the safety interval of ships is taken as the time interval between two ships in the channel. (Xu et al., 2004). Based on the characteristics of inbound ship, the conditions of the channel, and their experience, Tianjin Port determines the safe spacing of a ship is six times the length of the ship (Deng et al., 2004).
