Abstract
The purpose of the study presented in this paper was to investigate if there is any difference between the red light violation characteristics at traffic lights with properly designed clearance intervals and those which do not have an appropriate yellow change interval and, more importantly, those that do not have any all-red interval. An evaluation of before and after accident frequencies was also performed to determine the effectiveness of implemented improvements on right-angle crashes and injuries. These treated intersections did not have any all-red clearance before the improvements. A study of several junctions in Detroit (USA) included the identification of red light violation problems and strategies to alleviate them.