By Nishant Jayaram
Copyright jalopnik
When you see a huge, menacing pickup truck pop up in your rearview mirror, ever wonder what those five amber lights on top are for? Well, they’re to tell you that the vehicle in your mirror is … big.
They aren’t installed by owners to make large trucks more intimidating; they’re required by law. Marker lights are mandatory for vehicles wider than 80 inches under Federal Motor Vehicle Safety Standard 108, and the two types of them — identification lights and clearance markers — serve different purposes. Identification lamps are the three closely positioned lights at the truck’s center, while clearance lights are the ones on both outer ends. Unlike LED lights and spotlights, their purpose isn’t to illuminate the road ahead for better visibility. It’s to warn fellow motorists that a big boy is coming their way.
The identification lights in the middle notify other motorists that a wide vehicle is approaching, requiring more lane space than most other vehicles on the road. The clearance lights on the corners, as the name suggests, outline the vehicle’s width to show just how wide it is. The three identification lights must be mounted at the same level and, to get more technical, be spaced 6 to 12 inches apart. As the standard states in the Code of Federal Regulations, they have to be placed “as near the top as practicable,” with the rule applying to the clearance lamps, too.
