SEASONAL SKID RESISTANCE VARIATIONS

This report describes the results of a three year study of seasonal and short term variations in skid resistance on representative pavements in Pennsylvania. Six pavements including dense graded and open graded asphalt concrete pavements with various aggregate types and a portland cement concrete pavement were tested for skid resistance protland cement concrete pavement were tested for skid on a daily basis each year from early spring to late fall, using the locked wheel method of test. Pavement texture measurements also were made on a monthly basis throughout the testing session. The test program revealed that skid resistance may vary as much as 25 percent during a single week and that these short term variations are predictable from weather information during the week prior to the day of the measurement. A long term (seasonal) polishing of the pavements was noted during the testing session followed by a recovery during the winter months. A model which provides corrections for seasonal and weather effects is proposed. This model is based on the rainfall during the week prior to the test, tire and pavement temperatures during the test, the time of the year and the polish susceptibility and polishing rate of the aggregate. (FHWA)