Andersson, K., Nilsson, G., and Salusjarvi, M.: The effect of recommended and compulsory use of vehicle lights on road accidents in Finland. Report 102A. National Road and Traffic Research Institute, Linkoping, Sweden, 1976.
A study in Finland conducted between 1968 and 1974 found that DRLs, when required on rural roads in the winter, were associated with a 21-percent reduction in daytime multiparty crash events (involving more than one motor vehicle or motor vehicles colliding with pedestrians or pedalcyclists).
Andersson, K., and Nilsson, G.: The effect on accidents of compulsory use of running lights during daylight hours in Sweden. Report 208A. National Road and Traffic Research Institute, Linkoping, Sweden, 1981.
In Sweden, a study based on 2 years of pre-law and 2 years of post-law data reported and 11-percent reduction in multiparty daytime crashes subsequent to the DRL law.
Vaaje, T.: Kjorelys om dagen reducerer ulykkestallene. Arbetsdokument 15.8.1986. Transportokonomisk institutt, Postboks 6110 Etterstad, N-0602 Oslo 6, Norway, 1986.
A study in Norway published in Norwegian and reviewed by Koornstra found a 14-percent drop in multiparty crashes prior to the law, during the 1980-85 period when voluntary DRL use was climbing.
Elvik, R.: The effects on accidents of compulsory use of daytime running lights for cars in Norway. Accid Anal Prev 25: 383-398 (1993).
A study in Norway, covering the period 1980 to 1990, examined the effect of the country's DRL law, which applied to new cars in 1985 and to all cars beginning in 1988. DRL use was estimated to be about 30-35 percent in 1980-81, 60-65 percent in 1984-85, and 90-95 percent in 1989-90, so, as in the earlier Scandinavian studies, only partial implementation of DRLs was assessed. There was a statistically significant 10-percent decline in daytime multiple-vehicle crashes associated with DRLs in this study, excluding rear-end collisions, which increased by 20 percent. For all daytime crashes involving multiple parties, there was a statistically significant 15-percent reduction associated with DRLs in the summer but not in the winter. No significant effects of DRLs were found for collisions involving pedestrians or motorcyclists.
Hansen, L. K.: Daytime running lights in Denmark--Evaluation of the safety effect. Danish Council of Road Safety Research, Copenhagen, 1993; Hansen, L. K.: Daytime running lights: Experience with compulsory use in Denmark. Fersi Conference, Lille, 1994.
Two studies evaluating Denmark's 1990 DRL law have been completed, one that assessed short-term effects, the other looking at longer term effects. Results of these two studies were quite consistent. There was a small reduction in daytime multiple-vehicle crashes (7 percent) in the first year and 3 months the law was in effect, with one type of DRL-relevant crash (left turn in front of oncoming vehicle) reduced by 37 percent. In the second study, which covered 2 years and 9 months of the law, there was a 6-percent reduction in daytime multiple-vehicle crashes, and a 34-percent reduction in left-turn crashes. There was a small reduction in motor vehicle-pedalcyclist collisions (4 percent) but a statistically significant increase (16 percent) in motor vehicle-pedestrian collisions.
Cantilli, E. J.: Accident experience with parking lights as running lights. Highway Research Record Report No. 32. National Research Council, Transportation Research Board, Washington, DC, 1970.
In the United States, a small-scale fleet study conducted in the 1960s found an 18-percent lower daytime, multiple-vehicle crash rate for DRL-equipped vehicles.
Stein, H. S.: Fleet experience with daytime running lights in the United States. Technical Paper 851239. Society of Automotive Engineers, Warrendale, PA. 1985.
In a much larger fleet study conducted in the 1980s, more than 2,000 passenger vehicles in three fleets were equipped with DRLs.
One fleet operated in Connecticut, another in several States in the Southwest, and the third operated throughout the United States. A 7-percent reduction was found in daytime multiple-vehicle crashes in the DRL-equipped vehicles compared with control vehicles.
Aurora, H., et al.: Effectiveness of daytime running lights in Canada. TP 12298 (E). Transport Canada, Ottawa, 1994.
In a study in Canada comparing 1990 model year vehicles (required to have DRLs) with 1989 vehicles, a statistically significant 11-percent reduction in daytime multiple-vehicle crashes other than rear-end impacts was estimated. This estimate was adjusted to take into account the fact that about 29 percent of 1989 vehicles were fitted with DRLs. Collisions involving pedestrians, pedalcyclists, motorcyclists, and heavy trucks and buses were not included in this study.
Sparks, G. A., et al.: The effects of daytime running lights on crashes between two vehicles in Saskatchewan: a study of a government fleet. Accid Anal. Prev 25: 619-625 (1991).
In another Canadian study, crashes of vehicles with and without DRLs in a government fleet in Saskatchewan were compared with a random sample of crashes involving vehciles without DRLs. The estimated reduction in daytime two-vehicle crashes was 15 percent. When the analysis was limited to two-vehicle collisions most likely to be affected by DRLs--involving vehicles approaching from the front or side--the estimated reduction was 28 percent.
I'm not going to lie to you pipBOY, multiple countries have seen a decrease in collisions with DRL's.