PRACTICAL IMPLICATIONS OF SOME FUNDAMENTAL PROPERTIES OF TRAVEL-DEMAND MODELS

THE 2 MAJOR APPROACHES TO FINDING EQUILBRIUM BETWEEN SUPPLY AND DEMAND IN A NETWORK ARE THE INDIRECT, WHICH USES A SEQUENTIAL DEMAND MODEL, AND THE DIRECT, WHICH USES AN EXPLICIT DEMAND MODEL. THIS PAPER DESCRIBES THE GENERAL SHARE MODEL THAT CAN BE USED IN EXPLICIT FORM IN A DIRECT APPROACH TO COMPUTING EQUILIBRIUM OR IN THE FORM OF A SEQUENCE OF EQUATIONS IN AN INDIRECT APPROACH. A NUMBER OF PRACTICAL IMPLICATIONS FOLLOW FROM THESE THEORETICAL RESULTS. A NEW MODEL SYSTEM SHOULD BE DEVELOPED WITHOUT THE SERIOUS LIMITATIONS AND INTERNAL INCONSISTENCIES OF THE URBAN TRANSPORTATION MODEL SYSTEM, WHICH USES THE INDIRECT, SEQUENTIAL APPROACH. SUCH A NEW SYSTEM CAN BE VERY GENERAL AND DESIGNED TO COMPUTE EQUILIBRIUM WITH THE GSM IN A DIRECT APPROACH. OPTIONS CAN BE PROVIDED WITH A RICH VARIETY OF SPECIFIC DEMAND MODELS, AS SPECIAL CASES OF THE GENERAL SHARE MODEL, BUT WITHIN THE SAME GENERAL STRUCTURE. EFFICIENT PROCEDURES FOR COMPUTING EQUILIBRIUM MAY BE DEVELOPED BY EXPLOITING THE ELASTICITY PROPERTIES OF THE GENERAL SHARE MODEL. AS AN IMMEDIATE AND PRACTICAL STEP, PRESENT COMPUTER PROGRAMS SHOULD BE MODIFIED TO COMPUTE A VALID EQUILIBRIUM, TO INCLUDE LEVEL OF SERVICE EXPLICITLY AND CONSISTENTLY AT EACH STEP, ESPECIALLY TRIP GENERATION, AND TO INCORPORATE THE SPECIAL PRODUCT MODELS.

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  • Supplemental Notes:
    • Sponsored by Committee by Transportation Systems Design. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
  • Authors:
    • Manheim, Marvin L
  • Conference:
  • Publication Date: 1973

Media Info

  • Media Type: Digital/other
  • Features: Figures; References;
  • Pagination: pp 21-38
  • Monograph Title: Land use and transportation planning
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00242428
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 7 1973 12:00AM