Alternative formulations of a combined trip generation, trip distribution, modal split, and trip assignment model

Zhong Zhou, Anthony Chen, S. C. Wong

Research output: Journal article publicationJournal articleAcademic researchpeer-review

38 Citations (Scopus)


The traditional four-step model has been widely used in travel demand forecasting by considering trip generation, trip distribution, modal split and traffic assignment sequentially in a fixed order. However, this sequential approach suffers from the inconsistency among the level-of-service and flow values in each step of the procedure. In the last two decades, this problem has been addressed by many researchers who have sought to develop combined (or integrated) models that can consider travelers' choice on different stages simultaneously and give consistent results. In this paper, alternative formulations, including mathematical programming (MP) formulation and variational inequality (VI) formulations, are provided for a combined travel demand model that integrates trip generation, trip distribution, modal split, and traffic assignment using the random utility theory framework. Thus, the proposed alternative formulations not only allow a systematic and consistent treatment of travel choice over different dimensions but also have behavioral richness. Qualitative properties of the formulations are also given to ensure the existence and uniqueness of the solution. Particularly, the model is analyzed for a special but useful case where the probabilistic travel choices are assumed to be a hierarchical logit model. Furthermore, a self-adaptive Goldstein-Levitin-Polyak (GLP) projection algorithm is adopted for solving this special case.
Original languageEnglish
Pages (from-to)129-138
Number of pages10
JournalEuropean Journal of Operational Research
Issue number1
Publication statusPublished - 1 Oct 2009
Externally publishedYes


  • Combined travel demand model
  • Mathematical programming
  • Random utility
  • Transportation
  • Variational inequality

ASJC Scopus subject areas

  • Modelling and Simulation
  • Management Science and Operations Research
  • Information Systems and Management

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