LOCKED-WHEEL PAVEMENT SKID TESTER CORRELATION AND CALIBRATION TECHNIQUES

In an effort to develop and verify methods for improving the ability to reliably measure the skid resistance of wet pavement surfaces with skid testers in conformance with ASTM Method E-274, a project was initiated which involved contacts with skid tester owners to collect information on test equipment and operating procedures, conduct of laboratory and field experiments to determine the effect of specific variables on skid resistance measurements, and computer simulation studies on the influence of equipment dynamics on skid tester performance. The project also included the development of tentative recommendations for reducing variability in skid resistance measurement, and the conduct of a two-week skid tester correlation program to verify and modify the tentative recommendations. The study indicates that the precision of skid testers is generally better than their accuracy. Standardization of tester design is considered advisable particularly with regard to the watering system and the fifth wheel driven speed measuring system with a speed monitoring device for signalling to the driver departure from the selected speed. Further recommendations are made which relate to standardization of calibration procedures, operating procedures, operator training, criteria for determining number of pavement skids, and adherence to ASTM Method E274-70. To determine accuracy in absolute terms, dynamic calibration on stable reference surfaces is essential, and therefore, maximum effort must be devoted to developing such surfaces.