dieseldorf said:
http://www.openroad.com.au/motoring_roadsafety_headlightssafefeature.asp
http://www.arrivealive.co.za/pages.aspx?i=1819
How effective are DRLs?
Nearly all published reports indicate DRLs reduce multiple-vehicle daytime crashes. Evidence about DRL effects on crashes comes from studies conducted in Scandinavia, Canada, and the United States. A study examining the effect of Norway's DRL law from 1980 to 1990 found a 10 percent decline in daytime multiple-vehicle crashes.
1 A Danish study reported a 7 percent reduction in DRL-relevant crashes in the first 15 months after DRL use was required and a 37 percent decline in left-turn crashes.
2 In a second study covering 2 years and 9 months of Denmark's law, there was a 6 percent reduction in daytime multiple-vehicle crashes and a 34 percent reduction in left-turn crashes.
3 A 1994 Transport Canada study comparing 1990 model year vehicles with DRLs to 1989 vehicles without them found that DRLs reduced relevant daytime multiple-vehicle crashes by 11 percent.
4
In the United States, a 1985 Institute study determined that commercial fleet passenger vehicles modified to operate with DRLs were involved in 7 percent fewer daytime multiple-vehicle crashes than similar vehicles without DRLs.
5 A small-scale fleet study conducted in the 1960s found an 18 percent lower daytime multiple-vehicle crash rate for DRL-equipped vehicles.
6 Multiple-vehicle daytime crashes account for about half of all police-reported crashes in the United States. A 2002 Institute study reported a 3 percent decline in daytime multiple-vehicle crash risk in nine US states concurrent with the introduction of DRLs.
7 Federal researchers, using data collected nationwide, concluded that there was a 5 percent decline in daytime, two-vehicle, opposite-direction crashes and a 12 percent decline in fatal crashes with pedestrians and bicyclists.
8 However, a more recent federal study concluded that DRLs have no significant effect on either of these crash types.
9
5
Will DRLs shorten headlamp bulb life or lower fuel economy?
Running vehicle lights in the daytime does not significantly shorten bulb life. Systems like those on General Motors cars that use high beams are designed to operate at half their normal power during daylight hours, thereby conserving energy and reducing the effect on a vehicle's fuel economy. The National Highway Traffic Safety Administration (NHTSA) estimates that only a fraction of a mile per gallon will be lost, depending on the type of system used. GM estimates the cost to be about $3 per year for the average driver. Transport Canada estimates the extra annual fuel and bulb replacement costs to be $3-15 for systems using reduced-intensity headlights or other low-intensity lights and more than $40 a year for DRL systems using regular low-beam headlights.
1Elvik, R. 1993. The effects on accidents of compulsory use of daytime running lights for cars in Norway.
Accident Analysis and Prevention 25:383-98.
2Hansen, L.K. 1993. Daytime running lights in Denmark: evaluation of the safety effect. Copenhagen, Denmark: Danish Council of Road Safety Research.
3Hansen, L.K. 1994. Daytime running lights: experience with compulsory use in Denmark.
Proceedings of the Fersi Conference. Copenhagen, Denmark: Danish Council for Road Safety Research.
4Arora, H.; Collard, D.; Robbins, G.; Welbourne, E.R.; and White, J.G. 1994. Effectiveness of daytime running lights in Canada. Report no. TP-12298. Ottawa, Ontario: Transport Canada.
5Stein, H. 1985. Fleet experience with daytime running lights in the United States. SAE Technical Paper Series 851239. Warrendale, PA: Society of Automotive Engineers.
6Cantilli, E.J. 1970. Accident experience with parking lights as running lights.
Highway Research Record 332:1-13. Washington, DC: Transportation Research Board.
7Farmer, C.M. and Williams, A.F. 2002. Effects of daytime running lights on multiple-vehicle daylight crashes in the United States.
Accident Analysis and Prevention 34:197-203.
8Tessmer, J.M. 2004. An assessment of the crash-reducing effectiveness of passenger vehicle daytime running lamps (DRLs). Report no. DOT HS-809-760. Washington, DC: National Highway Traffic Safety Administration
9Wang, J.S. 2008. The effectiveness of daytime running lights for passenger vehicles. Report no. DOT HS-811-029. Washington, DC: National Highway Traffic Safety Administration.
