TIME-TO-COLLISION AND DRIVER DECISION MAKING IN BRAKING

In research on traffic conflicts techniques the time-to-collision (ttc) measure has proven to be effective for rating the severity of traffic conflicts between road users. In general, only interactions with a minimum ttc less than 1.5 s are considered critical and trained observers appear to be able to operate rather consistently in applying this threshold value. The analysis of behaviour in various other situations also points to the use of time related measures in decision-making in road traffic. Experiments on estimating ttc values show that ttc is consistently underestimated. To evaluate driver use of ttc when actually taking evasive action, a field experiment was conducted where subjects approaching a stationary object were instructed to start braking at the latest moment they thought they could stop in front of the object. The results reveal that ttc at the onset of braking increases with speed, but less than could be expected from a constant deceleration model. The minimum ttc as reached during the approach is rather independent of speed, normal or hard braking instruction, and driver experience. Excluding the direct perception of ttc from the optic flow field by stroboscopic occlusion substantially deteriorates the performance of drivers. These results support the hypothesis that both the decision to start braking and the control of braking is based on ttc information available from the optic flow field.(a)

  • Corporate Authors:

    TNO INSTITUTE FOR PERCEPTION

    KAMPWEG 5, PO BOX 23
    SOESTERBERG,   Netherlands  3769 ZG
  • Authors:
    • VAN DER HORST, ARA
    • Brown, G R
  • Publication Date: 1989

Language

  • Dutch

Media Info

  • Pagination: 36 p.
  • Serial:
    • Issue Number: C-23

Subject/Index Terms

Filing Info

  • Accession Number: 00498851
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Sep 30 1990 12:00AM