Federal DOT Regulations for a Semi-Trailer Bumper

By June Farquhar - Updated March 21, 2018
Parked Semi-Truck

The United States Department of Transportation (USDOT) requires requires trailers and semi-trailers to be equipped with rear impact guards (or bumpers) in order to reduce the risk of death and serious injury from light vehicles crashing into the back of semi-trailers. These rear impact guards must meet the requirements outlined in the Federal Motor Vehicle Safety Standard regulations that were in effect at the time of the truck's manufacture.

Exempted from the rear impact guard requirement are pole trailers, pulpwood trailers, low chassis, special-purpose, wheels back vehicles, and trailers transported in a drive-away or tow-away operation.

Installation of Rear Impact Guards

The trailer's manufacturer must attach a rear impact guard to the semi-trailer’s chassis in accordance with the installation procedures provided in the Federal Motor Vehicle Safety Standard, which details the rules for rear impact guards.

Additionally, the semi-trailer must be of the type specified in the rear guard's installation instructions. In other words, the rear impact guard installed on the semi-trailer must have been manufactured specifically for that type of semi-trailer.

Size and Positioning of Rear Impact Guard

The rear impact guard must extend horizontally to within four inches of the side of the truck, but no further. The distance between the bottom of the bumper and the ground must not exceed 22 inches at any point. Finally, the rear surface of the guard must be within 12 inches of the rear surface of the truck, and its height must be at least 3.94 inches.

Certification and Labeling

Each rear impact guard must be labeled or permanently marked on the outside area 12 inches in from the right side so that it may be easily seen. Information of the label or marking must contain the bumper manufacturer’s name and address, the month and year it was manufactured, and the letters “DOT,” certifying that the bumper conforms to all requirements of the Federal Motor Vehicle Safety Standard. All semi-trailers, regardless the state they’re in, must have this federal certification on the bumper. The manufacturer of the bumper must be contacted in the case of a bumper not being labeled.

Repairing a Damaged Rear Impact Guard

Semi-trailer rear impact guards that are damaged in an accident should be repaired properly and promptly. If the damage is relatively minor -- for example, the guard sustains small bends in the surface -- that repair can consist merely of straightening out the surface.

If the damage sustained by the bumper is more significant, or if a component piece is damaged, the affected part must be replaced. Additionally, the person making the repairs must prime and paint all replacement pieces in a manner to match the original rear impact guard and all its component parts.

Bear in mind that any repairs or parts that are replaced on semi-trailers manufactured after 1998 must meet all applicable federal standards, while earlier models may be exempt. The rear impact guard also must be properly labeled or marked to certify that it meets DOT requirements.

About the Author

June Farquhar has been writing for newspapers and special publications in California since 1998. She's the recipient of a press club award for organizing and designing a 42-page "Red Ribbon Week" tabloid, which received recognition from the California State Assembly and the U.S. House of Representatives. Farquhar studied newspaper journalism at Bakersfield College.

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