SPECIFICATION, AGGREGATION AND BIAS ESTIMATION FOR TRANSPORT SYSTEM PERFORMANCE MODELS - A PRELIMINARY REPORT

This paper discusses several aspects of network aggregation, the procedure of approximating a highly detailed transport network by a less detailed approximating network with much fewer nodes. Network aggregation is potentially important in transport system performance modelling, where some aspect of performance, such as travel time, is to be expressed as a function of demand. Several approaches to spatial aggregation as a computing tool are reviewed: (1) aggregation to a single link; (2) aggregation to a continuum; (3) aggregation from a fine to a coarse network. The aggregation of related cost functions (performance-flow relations) is discussed. Some mathematical results are then presented on consistent aggregation for networks. Two simple numerical examples are given, to illustrate the differences between individual link cost functions and the aggregate cost function for the case of parallel links. Although aggregate cost functions can be computed easily for simple cases like parallel and series connections, the problems appears to be much more difficult for general networks.

  • Corporate Authors:

    University of Oxford

    Transport Studies Unit, 11 Bevington Road
    Oxford,   United Kingdom  OX2 6NB
  • Authors:
    • Hazelton, M
  • Publication Date: 1993

Language

  • English

Media Info

  • Features: References;
  • Pagination: 15 p.
  • Serial:
    • TSU REF
    • Issue Number: 772
    • Publisher: University of Oxford

Subject/Index Terms

Filing Info

  • Accession Number: 00668174
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Nov 2 1994 12:00AM