The Slipperiness of Road Surfaces

Road Research Board Publication

Apparatus for accurately comparing the ''slipperiness" of various road surfaces, both at the time of laying and after wear, has been brought to a high state of development at the Road Research Laboratory of the Department of Scientific and Industrial Research. The machine used consists essentially of a motor-cycle and sidecar in which the sidecar wheel can be set at an angle to the direction of travel. The sideways force at right angles to the wheel exerted on it by the road, and the load on the wheel are measured, and from records obtained with instruments carried in the sidecar, the ratio of these forces is obtained and expressed as a coefficient which is high for good non skid surfaces and low for poor ones. The construction and operation of the motor-cycle and the sidecar and of the measuring apparatus is described in a Road Research Bulletin issued jointly by the Department of Scientific and Industrial Research and the Ministry of Transport (Road Research Bulletin No. 1, Measurement of the Non-skid Properties or Road Surfaces, H.M. Stationery Office. 9d. net). The Director of Road Research Dr. Stradling, states therein that the machine has been in regular use for a number of years and it is believed that its development has now reached a point where it may be usefully employed by any road engineer or surveyor to enable him to measure and compare for himself the frictional properties of the road surfaces for which he is responsible. It is estimated that the cost of the outfit should be approximately £475.