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EXACT METHODS FOR GRAVITY TRIP DISTRIBUTION MODELS

Gravity type trip distribution models are widely used to predict trip matrices. One of the reasons for the popularity of gravity type models is that simple and fast methods for computation of the trip matrices exist. However, these solution methods will not solve the original trip distribution problem, but a relaxed problem in which the discrete and combinatorial nature of the problem is not taken into account. This paper presents solution methods for the gravity trip distribution model which do take into account the discrete ingredients in the model. It will be shown that with a certain amount of extra computational effort it is possible to derive the exact trip matrix (the exact solution to the model) and not just an asymptotic estimate of it. The solution methods presented are based on separable programming techniques applied to the integer problem. A one-step method is presented as well as the iterative shrinking interval and moving interval methods. Results that show the difference between the resulting trip matrices using the exact method and the continuous approximation are also presented. (Author/TRRL)

  • Corporate Authors:

    Linkoeping University, Sweden

    Department of Mathematics
    S-58183 Linkoeping,   Sweden 
  • Authors:
    • Holmberg, K
    • Joernsten, K O
  • Publication Date: 1984

Media Info

  • Features: References; Tables;
  • Pagination: 53 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00391286
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • Report/Paper Numbers: 84-19 Monograph
  • Files: ITRD, TRIS
  • Created Date: Jan 30 1985 12:00AM