用自由效用模型刻画出行选择行为

Describing Traveler Choice Behavior Using the Free Utility Model

出行需求预测是交通规划与管理中的一个重要环节,四阶段法是传统出行需求预测中最常采用的流程。尽管研究者在四阶段法的各阶段中已经建立了大量模型,但仍缺乏能刻画不同阶段中相互作用的出行者群体出行选择行为的统一建模框架。本文采用在数学形式上与物理学中亥姆霍兹自由能函数一致的自由效用模型来分别和组合刻画出行者的出行方式、目的地和路径选择行为。自由效用模型的基本假设是相互作用的出行者们会通过权衡期望效用和信息处理成本来使自身的效用最大化。该模型不仅为群体出行选择行为提供了一个统一的建模框架,还为理解交通科学中的用户平衡模型和博弈论中的势博弈模型提供了新的视角。

Travel demand forecasting is an essential part of transportation planning and management.The four-step travel model is the traditional and most-common procedure utilized for travel demand forecasting,and many models have been proposed to describe each step separately.However,there is still a lack of a unified modeling framework that can successfully describe the collective choice behavior of travelers interacting with each other at different steps.This study uses the free utility model,in which the objective function is mathematically consistent with the Helmholtz free energy in physics,to separately and simultaneously describe travelers’mode,destination,and route choice behaviors.The free utility model’s basic assumption is that the travelers will trade off the expected utility and information-processing cost to maximize their own utility.This model provides not only a unified modeling framework for traveler choice behavior,but also provides a new perspective for understanding the user equilibrium model in transportation science and the potential game model in game theory.