Improved Analytical Model for Estimating the Capacity of a Waterway Lock

摘要

The many locks built in the development of inland waterborne transport networks in past decades have become major bottlenecks in the China waterway system. Capacity has become one of the most important waterway lock characteristics. However, capacity is difficult to determine because it varies with the operating conditions. Although a traffic simulation is suitable for analyzing lock capacity, a reasonable analytical model may be more feasible and efficient, especially in the planning stage. The typical analytical model loses adaptability when the sizes of navigation locks and freight vessels are not uniform. Moreover, the lock capacity should have enough reserve to meet the peak demand under heavy traffic flow to provide the required level of service. In this article, an improved analytical model for estimating the lock capacity based on the load factor of the chamber area, relationship between the area and tonnage (RAT) of a freight vessel, and daily peak factor with a certain guarantee rate is presented. Three interrelated indicators (i.e., guarantee rate, traffic load, and time delay) are used to measure the lock level of service (LLOS) comprehensively. LLOS criteria and threshold values are proposed for the current conditions in China. Based on field data regarding the Beijing-Hangzhou Grand Canal, Yangtze River, and Xijiang River, the validations show that the improved model is reasonable, feasible, and very useful for an inland waterway network with nonuniform lock and vessel sizes. Additionally, optimal scheduling can be conducted based on the improved model to promote the development of uniform freight vessels in fully loaded operations as much as possible.