An experiment is described which measured drivers' accuracy in carrying out different instructions about spacing between following vehicles. As many as 1/3 of the subjects felt that the existing highway code recommendation of 1 yd per 1 mile/h (just over 2 seconds) was too great. Thus there is A need to convince drivers that such spacings are necessary in the interest of road safety. Attempting to follow 2 seconds behind another vehicle by selecting a distance which enabled the phrase "keep a safe distance, keep a safe distance" to be said in the time interval between following vehicles was found to be the most consistent instruction. Nevertheless at 30 mile/h and 40 mile/h up to 1/6 of drivers followed at less than 1 second. For practical use it would therefore be desirable to increase the target mean time. Other instructions caused drivers to follow at greater time intervals but there were much wider variations in the choices made and it is unlikely that the much greater distances chosen by some drivers would be maintained on the road. (A) /TRRL/

  • Corporate Authors:

    Transport and Road Research Laboratory (TRRL)

    Wokingham, Berkshire  United Kingdom 
  • Authors:
    • MACKIE, A M
    • Russam, K
  • Publication Date: 1975

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 14 p.
  • Serial:
    • Issue Number: SR1

Subject/Index Terms

Filing Info

  • Accession Number: 00132247
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: R&D Rpt.
  • Files: ITRD, TRIS, ATRI
  • Created Date: Jun 23 1976 12:00AM