Project Y.A.M. (Yaw Analysis Methodology), vehicle testing and findings of Victoria Police, Accident Investigation Section

A vehicle oversteered or cornering at excessive speed results in the tyres of the vehicle losing traction with the road surface. As a result tyre yaw marks may be left on the road surface. Yaw marks are common at fatal collision sites. Various methods are reported to estimate the speed of the vehicle that leaves yaw marks on a road surface. The equation to calculate speed in each method is basically the same. Equation inputs involve the radius of the path of vehicle and the friction forces acting between tyres of the vehicle and the road. The essential differences in each method are how to determine the radius and whether the peak or average friction is used in the equation. The Victoria Police, Accident Investigation Section conducted 110 tests at Avalon Airport, Victoria, Australia, in February. 1996. Four different vehicles were tested. During testing, variations in tyre pressures, and driver inputs of acceleration, braking and steering over-correction were looked at. The effects of yawing followed by emergency braking with and without ABS braking was further studied. The methods adopted currently by the Victoria Police, Accident Investigation Section in estimating speed from yaw marks were validated and found conservative. Radar speed of the vehicle for each test was compared with speed estimates from the yaw marks.


  • English

Media Info

  • Pagination: 173-216

Subject/Index Terms

Filing Info

  • Accession Number: 01392407
  • Record Type: Publication
  • Source Agency: ARRB
  • ISBN: 0731054717
  • Files: ATRI
  • Created Date: Aug 23 2012 7:07AM