Directional characteristics of traffic polishing effect on pavement skid resistance

This study demonstrated that skid resistance testing in traffic direction does not provide a complete evaluation of traffic polishing effect on pavement skid resistance. Directional British pendulum tests were performed on 14 pavement sections involving the following six modes of vehicle operation: (A) Acceleration, (B) Deceleration, (C) Moving from stop, (D) Stopping, (E) Constant-speed cruising, and (F) Cruising without constant-speed setting. Test results confirmed that there were statistically significant differential directional polishing effects in practically all modes of vehicle operation. The relative magnitudes of polishing action of different modes were evaluated. The strongest polishing effects were produced by mode A in the against-traffic direction, and mode B in the traffic direction. The next stronger polishing effect was achieved by the combined mode (C + D) in the traffic as well as the against-traffic direction. Comparatively, the lowest polishing effect was produced by modes E and F, in either the traffic or against-traffic direction. Test results also revealed different polishing directions and magnitudes caused by driving and driven wheels. Driving wheels were found to produce significantly stronger polishing effect than driven wheels.