Recent models of vehicle operating costs integrate unit costs over all significant variables. While these may be more powerful than earlier models, sensitivity tests indicate that some variables may be eliminated. In year over the speed-flow function may be unneccessary if vehicle speeds during the year have a consistent distribution. In a pilot study speeds were measured over 24 hours and the statistical characteristics of the speed distribution determined. The input data were simulated by use of a normal distribution model for one hour speeds. The simulation was extended to include a year's sample of speed data. The estimated speed-flow functions were found to have an approximately normal distribution in both cases. So, A more direct model for annual cost is therefore proposed. The conclusion is reached that the earlier cost models, which used annual average or representative values of speed, are adequate for the determination of operating costs. (a). For the covering abstract of the conference, see IRRD abstract no. 218019.


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 101-111
  • Serial:
    • Volume: 7
    • Issue Number: 3

Subject/Index Terms

Filing Info

  • Accession Number: 00134323
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • ISBN: 0 909996 709
  • Files: ITRD, TRIS
  • Created Date: Sep 16 1976 12:00AM