Measurement Principles Applied to Skid Testing

The real objective in skid testing is to determine the contribution of the pavement to tire-pavement friction. Friction force between a standard tire and the pavement is measured because there is, at present, no direct way of characterizing the pavement surface. Friction force depends on pavement and tire; therefore, the tire cannot properly be regarded as part of the measuring system. The skid tester, without tire, is discussed on principles of measurement techniques, and the conclusion is reached that statistical methods must be employed to compensate for the lack of precision in skid testing. Skid tester dynamics do not affect mean skid resistance; therefore, no basic design changes are required. Precision can be improved by tighter test procedures. These require improved training and awareness of operators, improved control of test speed, lateral position, and pavement watering.