Link choice proportions from trip distribution and assignment models: An overview and comparison
✍ Scribed by William H. K. Lam; H. J. Huang
- Publisher
- Institute for Transportation Inc.
- Year
- 1996
- Tongue
- English
- Weight
- 893 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0197-6729
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✦ Synopsis
Abstract
A number of estimation procedures have been suggested for the situation where a prior estimate of an origin‐destination matrix is to be updated on the basis of recently‐acquired traffic counts. These procedures assume that both the link flows and the proportionate usage of each link made by each origin‐destination flow (referred to collectively as the link choice proportions) are known. This paper examines the possibility and methods for estimating the link choice proportions. Three methods are presented: (1) using ad hoc iteration between trip distribution and traffic assignment; (2) combining trip distribution and assignment in one step; (3) solving a new optimization problem in which the path flows are directly considered as variables and its optimal solution is governed by a logit type formula. The algorithms, covergencies and computational efficiencies of these methods are investigated. Results of testing the three methods on example networks are discussed.