Abstract
A contributory factor in accidents at junctions, particularly at junctions on high speed roads, is that drivers do not reduce speeds sufficiently to allow them to negotiate the junctions safely. A special road marking has been developed employing a geometric bar pattern that affects drivers' judgements of speed causing them to slow down. Markings of this type were laid in october 1971 on the approaches to the newbridge roundabout on the m8 motorway, midlothian. Measurements during the following month showed considerable and consistent reductions in speed. During the sixteen months following the installation two accidents have been reported at the site; there were 14 in the previous year. (Author/publisher).