Study on redefinition of traffic flow parameters and basic diagram based on ship scale

The basis and premise for the study of Fundamental Traffic Flow Diagram are the traffic flow characteristics parameters. Most of the research on maritime traffic flow is simply a direct transfer and application of knowledge from road traffic flow. However, this assumes that there is minimal difference between maritime traffic flow and road traffic flow. Obviously, this assumption is difficult to make. The scale of different types of ships varies considerably, often differing by a factor often or twenty, in contrast to the relatively uniform scale of road traffic vehicles. This significant variation in scale renders the results obtained from the previously defined methods for solving road traffic flow characteristic parameters unrealistic. In order to discover a method for defining traffic flow characteristics parameters that aligns better with the characteristics of maritime traffic flow, this paper first analyzes the disparities between road and maritime traffic in terms of the dimensions of the means of delivery. Building upon these distinctions, it examines the impact on maritime traffic flow parameters. Subsequently, the paper proceeds to redefine the traffic flow characteristics parameters by utilizing separate definitions for ship length and ship area, respectively, to mitigate the influence caused by these dissimilarities. Firstly, the South Channel of the Yangtze River is selected as the target, and the traffic flow characteristics parameters are calculated under various definitions using the Automatic Identification System (AIS) data of the channel. The results are then used to create a fundamental traffic flow diagram in the channel. Finally, the fundamental traffic flow diagrams produced by these definitions are compared and analyzed. This study proposes a method for defining traffic flow characteristics parameters that take into account differences in vessel scales, which can more accurately reflect the traffic status of waterways and provide a more scientific basis for water traffic management and decision-making departments.