THE SAFETY OF ROUNDABOUTS IN FINLAND

There are about 200 roundabouts in Finland at present; of these, 140 are on public roads maintained by the Finnish National Road Administration. This study concerns safety at 87 roundabouts built on public roads between 1990 and 1997 and, for comparison purposes, two built in 1960. With the exception of two dual-lane roundabouts, the roundabouts studied are single-lane. They are all located in the centre or periphery of built-up areas, mostly on regional or connecting roads. 23 of the roundabouts studied are on main roads, 6 in the centre and 17 on the periphery of built-up areas. By the end of 1998 a total of 195 reported accidents had occurred on the roundabouts built in the 1990s. Of these, 29 involved personal injury; there were no fatalities. All the injury accidents were classified as minor on the basis of the police accident report forms. The accident rate for all the accidents in the study is 0.26 (accidents per million vehicles entering the roundabout); the accident rate for injury accidents is 0.04. The traffic volume and the size of the central island were not found to correlate significantly with the accident risk. The accident risk at a roundabout depends on its location. Roundabouts on class I and II main roads have a higher accident rate than those on regional and connecting roads. The most common types of injury accident at roundabouts on class I and II main roads are run-off onto the central island, rollover and run-off outwards. On main roads, more accidents occur on the periphery of built-up areas than in the centre. The accident rate for all accidents on the periphery is 0.35, and the rate for injury accidents is 0.06. At roundabouts on main roads on the periphery of built-up areas, the risk of an accident in the first year after the roundabout is opened to traffic is over 1.5 times higher than average. The most commonly occurring accidents are collisions on approach (52 accidents, 26.7%), followed by run-offs onto the central island (36, 18.5%) and rear-end collisions (29, 14.9%). The most common injury accidents are those involving bicycles and mopeds (10, 34.5%), followed by run-offs onto the central island (8, 27.6%). The most common accidents involving cars and vans were collisions on approach, run-offs onto the central island and rear-end collisions. The most common injury accidents here are run-offs onto the central island and collisions with a bicycle or moped. For heavy vehicles, the most common accidents were rollovers and run-offs outwards. With the exception of one motorcyclist, all rollovers have involved heavy vehicles. Of the 7 heavy vehicle rollovers, 4 occurred on roundabouts on class 1 and 11 on main roads. Of the accidents involving a bicycle and a car, 10 occurred on crossings: 1 on approaching the roundabout and 9 on exiting it. In 4 cases the cyclist was drunk. There were 3 pedestrian accidents at roundabouts, none of which caused injury.