Although not a direct substitute for headlights or fog lights, daytime running lamps help make you more visible to other drivers. DRLs have been a standard feature in cars since the ’90s. Here we will look at where DRLs came from, their use cases, and current regulations.
DRL vs. Headlights
Daytime running lamps are lights at the front of a vehicle that is left on during the daytime to provide additional visibility to surrounding drivers. Most cars today have DRLs that remain on whenever the engine is running. Unlike headlights, DRLs are not meant to illuminate the road in front of you.
The Origin of DRLs
DRLs originated in Scandinavia, where the winter months bring far more hours of darkness. Less visible light combined with snowy conditions drove the need for added safety. Finland first mandated DRL use in 1972 for driving on rural roads. DRLs improved driver safety in these conditions, and other Scandinavian countries followed suit with similar legislation.
DRL Use Cases
The use cases for daytime running lamps are said to be:
- DRLs improve the contrast between vehicles and their background
- DRLs can alert drivers to approaching vehicles on winding roads where they are not directly visible
- DRLs provide extra safety while driving through a construction zone
As for their efficacy, the National Highway Traffic Safety Administration conducted research on DRL use and crash data. DRLs reduced daytime crashes specifically among trucks and vans (5.7%), but for other crash types, no significant statistical impact was found.
DRL Regulation the US
Interestingly, before the ’90s, DRLs were not allowed on US highways. It was the petitioning of General Motors to the NHTSA that lead to the common use of DRLs.
Because their efficacy has yet to be demonstrated, the US will not federally mandate DRLs. However, several countries, including Canada and the UK, currently require the use of DRLs at all times.
DRLs are inexpensive to run. The fuel cost they incur during a year of driving is negligible. For this reason, DRLs are extremely common but not legally required in the US. Should daytime running lamps be mandated?
It seems like they don’t need to be. Most vehicles already use them, and for the fraction that don’t, no statistical safety advantage of their use has been found.
Eighteen states, including New York and California, mandate that headlights be on whenever windshield wipers are on. This mechanism increases visibility during bad weather conditions. But DRLs are not considered headlights, so in practice, they aren’t required in the US.