Daytime running light
What are daytime running lights?
Daytime running lights (DRL) are designed to make a vehicle more visible to other road users whilst driving during the day.
Unlike low beam headlights and high beam headlights, daytime running lights are not primarily intended to illuminate the road. Their main purpose is to improve the visibility of the vehicle.
Daytime running lights are located at the front of the vehicle and emit white light.
Daytime running lights and dipped headlights
Daytime running lights and low beam headlights serve different purposes. Low beam headlights produce a defined beam pattern, which illuminates the road without unduly dazzling other road users. Daytime running lights, on the other hand, are primarily intended to make one’s own vehicle visible.
Consequently, the requirements for light distribution also differ.
Daytime running lights therefore do not replace dipped headlights when visibility conditions require the road to be illuminated.
Automatic daytime running lights
On vehicles equipped with this feature, the daytime running lights are activated automatically. When the low beam headlights are switched on, the daytime running lights are switched off or their function is adjusted in accordance with the applicable switching regulations.
Which other vehicle lights are switched on together with the daytime running lights depends on the vehicle model and the applicable regulations. It cannot therefore be assumed, based solely on the daytime running lights being on, that the rear lights are also switched on.
Regulations for daytime running lights
There are defined requirements for light colour, luminous intensity and light distribution for approved daytime running lights. According to UN ECE Regulation No. 148, daytime running lights bear the functional designation RL. Defined minimum and maximum values for luminous intensity, as well as requirements for light distribution, are prescribed.
The requirements for mounting and the electrical circuit on the vehicle are governed in particular by UN Regulation No. 48. Daytime running lights are therefore a component of vehicle lighting, the function and photometric characteristics of which must be clearly distinguished from the actual road illumination.