This report is comprised of the following partial studies and reports: Literature report on lighting safety studies. Before and after study on the impact on safety of road lighting constructed in the 1990s. Before and after study on the impact of road lighting on driving speeds based on data from automated traffic measurement points. A sum-up estimation of the impact of road lighting on traffic accidents and driving speeds was compiled based on the different partial studies. Literature report on lighting safety studies The literature report broadly examined primarily European and US reports and articles on the impact of road lighting on safety and speeds. Accident risk on unlit roads is clearly greater in the dark than in daytime and, on average, accidents that occur in the dark are more serious. Several studies determined that the risk of a personal injury accident is 1.5 times greater in the dark than in daytime. Especially the share of accidents involving pedestrians increases in the dark. As a rule, construction of road lighting was found to reduce night-time accidents 20-40%. The number of serious accidents was reduced more than average. Several studies indicated that the number of pedestrian accidents decreased more than average. Partial switching off or dimming of road lighting has been studied for energy conservation reasons. The increase in the cost of accidents is greater than the savings in electricity. Switching off lighting always results in more accidents. Several studies on improving the current level of lighting indicate that this measure slightly reduces the number of accidents. A few studies examined the impact of road lighting on driving speeds. In Sweden it was found that as a result of constructing road lighting, driving speeds increased 3.6 km/h on straight sections of road and 0.5 km/h on curving sections. Also in Germany it was noted that improving road lighting increased driving speeds. Before and after study on the impact on safety of road lighting was carried out in the 1990s. The study material comprised 236 locations. In 184 locations only road lighting was constructed, while in 52 locations other measures were also implemented. Based on the before and after study, it was concluded that constructing only road lighting reduced the number of personal injury accidents around 17% and the total number of accidents around 11%. The impact of road lighting on night-time accidents is significantly greater: 45-55% for personal injury accidents and 30-4 % for all accidents. Construction of road lighting reduces pedestrian and bicycle accidents about 17%, animal accidents only about 3%, single-vehicle accidents about 8% and other accidents about 14%. The large reduction in pedestrian and bicycle accidents means the degree of seriousness of accidents decreases due to road lighting. The small reduction in animal accidents is due to an increase in the number of European moose by about one third in 1988-2002. Road lighting together with pedestrian and bicycle paths clearly appears to reduce the number of accidents, and especially personal injury accidents, more than road lighting alone. The data on other combined measures are too limited to permit drawing conclusions. Before and after study on the impact of road lighting on driving speeds based on data from automated traffic measurement points The impact of road lighting on driving speeds was studied based on speed data from automated traffic measurement points (ATM points). The study included ATM points where road lighting was constructed after 1997, but where no other changes were made. Hourly average speeds in September at the nine points one year before and one year after the construction of road lighting were compared. Contrary to anticipations and a few results in the literature report, it was found that road lighting did not increase driving speeds on main roads. The result is the same with both 100 km/h and 80 km/h speed limits. One explanation may be that speeds in the dark are already close to the limit, and, regardless of the lighting. This report may be found at http://alk.tiehallinto.fi/julkaisut/pdf/3200868-vtievalvaik.pdf
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