A technique is described, using readily available equipment, which is far less costly than conventional aerial photography. Data extraction is simplified by the use of a semi-automatic method of obtaining digital data which may then be processed on a computer to provide information on many traffic flow parameters. Details are given of the method, using a hovering helicopter, and the 16 mm and 35 mm equipment used. Although it is possible to extract data from the film using conventional manual means, it is very tedious. The method developed codes vehicles according to colour, type and lane of travel. These codes and associated co-ordinates are stored in a computer. A program is then written to match consecutive vehicle positons and follow each vehicle through the study areas. Because vehicle codes were not unique, a system of zoning was used. It was found that there was no significant difference between the errors produced by linear or projective transformation. Projective transformation was preferred, because it required fewer control points for the same accuracy. Overall the 35 mm equipment gave better results but the lower cost of 16 mm photography had advantages. It was found that there was A 90 per cent probability of matching vehicles in successive 35 mm frames. This probability fell to 87 per cent using 16 mm (TRRL)

  • Supplemental Notes:
    • Conference on Traffic Data Collection, Leeds University, January 8-9, 1979.
  • Corporate Authors:

    University of Leeds

    Department of Civil Engineering
    Leeds, West Yorkshire  United Kingdom  LS2 9JT
  • Authors:
  • Publication Date: 1979

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 21 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00335302
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: Nov 23 1981 12:00AM