What should be the intensity of the STOP brake lights in a truck?
Show the correct answer
Correct answer
A. Significantly higher than the rear position lights.
Explanation
In the photo you can see the rear lamp of a lorry with red and amber lenses. STOP brake lights should have a luminous intensity clearly greater than the rear position lights - answer A.
The Regulation on the technical conditions of vehicles requires the brake light to come on when the service brake is applied, and its luminous intensity to be clearly greater than that of the rear position lights. Both lamps shine red and are often in the same housing, so the driver behind you recognises braking precisely by the sudden increase in brightness - if the intensity were the same or lower (answers B and C), the signal would be unclear and the driver would react a fraction of a second later. At a speed of 80 km/h, these fractions of a second mean a dozen or more metres. That is why a blown bulb or a dull, darkened STOP light lens is a fault that you fix before setting off; in a lorry you check these lights with the help of a second person or by parking the vehicle with its rear facing a wall.
Legal basis: Annex No. 6 to the Regulation on the technical conditions of vehicles and the scope of their necessary equipment; § 12 para. 1 point 4 of the Regulation on the technical conditions of vehicles and the scope of their necessary equipment