A wheel that partly revolves and partly skids is being used to detect bad surfaces on Britain's roads. The wheel is attached at an angle of 18簞 to a motorcycle combination and his behaviour on all sorts of road surfaces is recorded on a Graaf carried in the sidecar. A smooth tyre, which has to be changed every 60 miles, is used to standardised measurements. Main purpose of the new machine is to test experimental road materials, the trunk roads, and 'blackspots' to see if the road surface is the cause of the accident. For motorcycles, built for the Ministry of Transport, are being used in London, Exeter, Manchester and Edinburgh. Photo shows, the delicate recording apparatus in the sidecar of the motorcycle.