Bilevel Programming Model for City Logistics Distribution Optimization under Time Restriction Caused by Traffic Organization

Abstract

For the optimization of city logistics distribution under time restriction caused by traffic organization, a bilevel programming model considering the distribution cost, environment cost, and distribution time of enterprises is developed. The primary function of this upper-level model is to minimize the general cost of distribution enterprises and determine the scheme to optimize city logistics distribution. The lower-level model is the urban traffic equilibrium distribution model for analyzing the distribution route determined by choice behavior for the optimization scheme of city logistics distribution given by the upper-level model. Results indicate that the distribution time, distribution cost, and environment cost of distribution enterprises increased significantly, and that the income of distribution enterprises was reduced because of the traffic organization time window in the process of city logistics distribution. When a distribution task was required to be completed within the formulary time window, the distribution time increased from 5.91% to 7.32%, the distribution cost increased from 7.6% to 13.5%, and the environment cost increased slightly. During the traffic organization period, the distribution cost in the second time-restricted scene increased to 26.85% because of the two-fold impacts of the average freight charge and the traffic demand. When the change in network traffic demand was equal to the basic scene, the environment cost and the distribution time in the first time-restricted scene increased slightly. However, when comparing the restriction time under traffic organization and the total distribution time, the incremental quantities of the former distribution time and distribution cost were always more than the latter.