Research outline

Measuring the Slipperiness of Road Surfaces in Winter
Road Surface skid Resistance Monitoring System

A measuring test on the test track (two vehicles at the back are equipped with a continuous friction tester (CFT) to measure the road surface skid resistance)

Monitoring on the actual road

Information distribution site via the Internet (enlarged view below)
(Areas in green indicating non-slippery locations and areas in red indicating slippery locations)

In a cold, snowy region like Hokkaido, a reduction of road width and road surface freezing due to snow accumulation occur. After the enforcement of the studded tire regulation, in particular, extremely slippery road surfaces have appeared, which have been a major cause of traffic jams and accidents characteristic of winter.
CERI has been conducting research that contributes to more appropriate and accurate winter road management based on the quantitative and objective evaluation of the status of winter road surfaces for the establishment of efficient and effective method of winter road management.
In Japan, no measuring equipment has been available capable of measuring road surface slipperiness, which may vary depending on the location, and winter road management has been based on a visual inspection of road surface conditions. However, road surface conditions may not be easy to identify visually and there is individual variation in judgment. To allow winter road management based on quantitative and objective evaluation of winter road surfaces, we have introduced a recently developed continuous friction tester (CFT) device, capable of continuously measuring the slipperiness of a road surface, and are working establishing a road surface skid resistance monitoring method.
The research included verification of the reliability of measurements by means of measurement tests using the CFT. In addition, the slip friction values measured with the CFT were recorded together with the time and position data and used to make databases linked with digital road maps to build a road surface skid resistance monitoring system allowing map display and various kinds of analysis.
This system has made it possible to provide information on road surface slipperiness via map display. In reality, the results of monitoring the skid resistance on the surfaces of national roads in Hokkaido are provided via the Internet for road administrators to use as a reference for day-to-day road surface management.
Going forward, we intend to take advantage of the data accumulated by using the system for further research on the sophistication of techniques of winter road management using skid resistance, including the evaluation of day-to-day winter road management by understanding the effects of spreading anti-freezing agent and evaluating winter road management throughout the winter.

(Contact: Traffic Engineering Research Team, CERI)