The Mu-PW Friction tester as an element of road surface skid resistance evaluation system at the traffic accident scene

Conclusions regarding needs related with building of measurement device, used to road surface skid resistance evaluation in traffic accident scene, are presented in this paper. Review results of devices and testers used to road evaluation of road surface properties, which are responsible for tire-road grip coefficient, are presented. Methods of road surface skid resistance measurement have been evaluated, in the context of common use in the process of traffic accident scene description. In the case of portable devices there are generally indirect methods, using rubber specimen which is sliding on the road surface, under certain normal load. In such cases, the measurement results defined as friction coefficient can be correlated with a tire grip coefficient to the road surface. There has been shown that it is necessary to develop methods and technical means of road surface skid resistance evaluation, which ensure an increase a results reliability of road accidents reconstruction process. Assumption for building and design system of P-PW tester, have been presented. Established device concept is based on the measurement of the rubber specimen friction coefficient to the road surface. During the measuring the specimen normal load is fixed and motion speed is controlled. Features of tester and possible modes of measure, have been shown. An important feature of the tester is the possibility of transfer measurement results to a computer in order to prepare of test report, as an annex to the Police report of the vehicle inspection, used by the police in the procedure of traffic accident scene describing.