Abstract
A description is given of an experiment to assess the effect of equipping a length of motorway with 70 mph repeater signs upon vehicle speeds. The site chosen was a 20 mile section of the northbound carriageway of the M1 motorway terminating at junction 37 in Yorkshire. Data from the northbound carriageway were compared with that from the unsigned southbound carriageway. Similarly data from the year before the signs were unveiled on 1 September 1988, were compared with data for the year after.