This paper describes an analysis of accident rates before and after installing wide (2.7-2.9 m) raised median strips on arterial roads throughout the Adelaide metropolitan area. All roads were zoned at 60 km/h. The main comparison was with narrow (1.8 m) flush painted medians but a comparison was also made with a small group of narrow (1.2 m) raised medians. Accidents were examined by severity (casualty, property damage), location (midblock, intersection) and type (rear end, side swipe, right angle, fixed object, pedestrian, parked vehicle and other). The study examined a total of 34.7 km of roads with wide median treatment with at least two years before and after accident data and, where possible, three years before and after accident data. A control group of 20.0 km of roads without treatment was examined using eight years of accident data. The study showed that where a narrow painted median was replaced by a wide raised median the overall accident rate fell by 22%. (A)
Abstract