4.5. Non-contact measurement of friction
Emerging technologies are evaluating the computation of the pavement friction based on data from the vehicle (deceleration, slipping information for the traction control systems, etc.) and/or non-contact technologies (e.g., laser-based systems or image-processing) to measure microtexture. These alternatives to rubber-on-road techniques are laudable ideas and presently there are plenty of researchers looking into this, but they are, at the moment, not reliable techniques and are unlikely to work at traffic speed for some time.
For the immediate and probably medium term, “dragging a tire across a road” remains the only reasonably reliable way to assess the skid resistance of a road. It does at least have the virtue of measuring something relating to the rubber and the road – even though it will need to be standardized so that the measurement is transportable and not uniquely biased towards one rubber-road interaction with limited relevance to all others.