This paper gives some preliminary results of a Land Transport New Zealandfunded research project that is currently being undertaken in New Zealandto: (1) detect the presence of binder rise (flushing) from two-dimensional road surface profiles, and (2) quantify the influence of binder rise in reducing tire-road friction on surface dressing surfaces. Research indicates that there is a direct link between the risk of a crash in wet conditions and the level of skid resistance offered by a surface. By more accurately identifying flushed surfaces and quantifying the effects of binder risein reducing skid resistance, skid resistance management practices can be improved thereby reducing the number of crashes in wet conditions. This paper discusses two objectives of the research: (1) establish whether or notthe Dynamic Friction Tester can simulate high-speed Locked?Wheel Braking performance, and (2) quantify the friction reduction that occurs on flushed surfaces. The key finding is that surface dressing flushing reduces tire-road friction by approximately 0.1 units at 60km/h and reduces linearly with slip-speed at a rate of 0.01 per 20km/h.
Abstract