基于网络拓扑的子网络OD需求估计

Subnetwork origin-destination matrix estimation considering network topology

为了对局部交通路网进行设计和评价,运用拓扑结构分析方法对子网络OD需求进行估计.根据子网络拓扑结构,分别对子网络边界点和内部点的OD量进行分析,每个与外界网络相连的边界点都为子网络的交通发生吸引点,内部点OD需求量与原来网络保持一致.进而建立了基于网络拓扑的子网络OD需求估计模型,其中目标函数同时考虑了交通需求的熵最大化及弹性化,约束条件为子网络OD量约束.将原问题分为求解交通需求和道路阻抗两部分,设计了启发式迭代算法反复求解,并运用凸组合算法计算交通需求.运用Sioux Falls网络对算法和模型进行了测试,结果表明考虑弹性需求的子网络OD估计模型在可靠性和计算精度上均优于考虑固定需求的子网络OD估计模型,算法能够快速收敛到所需精度,建立的模型可以用来对实际路网进行简化.

To design and evaluate the local transportation road network,the subnetwork origin-destination(OD) demand is estimated using the method of topology analysis.The nodes on the boundary of the subnetwork and inside the subnetwork are analyzed based on the subnetwork topology structure.The nodes on the boundary of the subnetwork,which connect with the outside of the subnetwork,generate or attract traffic flows;and the demands of the nodes inside the subnetwork are the same as those in the original full network.Then,the subnetwork OD matrix estimation model considering the subnetwork topology is established.This new model considers the maximum entropy and elasticity of OD demands in the objective function,and uses the OD demands as the constraints.The original problem is divided into solving the OD demand and road impedance,respectively.The heuristic iterative algorithm is designed to solve the established model,and the convex combination algorithm is developed to calculate the OD demand.The Sioux Falls network is used to illustrate the essential idea of the proposed model and the applicability of the proposed solution algorithm.The results show that the proposed model with elastic demand is superior to the OD estimation model with fixed demand in the terms of reliability and computational accuracy.The designed algorithm can rapidly convergence to the required accuracy,and the proposed model is an effective approach for simplifying the full network.