SKID-RESISTANCE MEASUREMENTS WITH BLANK AND RIBBED TEST TIRES AND THEIR RELATIONSHIP TO PAVEMENT TEXTURE

A prediction model for the ratio of skid numbers obtained with the ribbed ASTM E501 test tire to those obtained with the blank ASTM E524 test tire at any speed has been developed by using data from 22 pavement test sites in Pennsylvania. The prediction is based on the Penn State model for skid-resistance speed behavior. The model was developed as a function of a macrotexture parameter defined by sand-patch mean texture depth (MTD). Application of this model permits the prediction of the blank-tire skid number at a test speed of 64 km/hr was also developed. Values calculated from both models show good agreement with each other as well as with the actual data. An effort was also made to relate skid resistance measured with both types of test tires to pavement texture. The results show a strong relationship between skid numbers with both test tires and pavement macrotexture and microtexture. Therefore, by performing a pavement skid-resistance survey with both the blank E524 and the ribbed E501 test tires, the levels of macrotexture and microtexture can readily be estimated. Seasonal and short-term variations in data with the two tires were also compared. Short-term variations do not pose as great a problem in the blank-tire data as in the ribbed-tire data. (Author)