DOT Laws for Gooseneck Trailers

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Gooseneck trailers differ from conventional trailers because they connect to the bed of a pickup truck rather than to a traditional hitch, located below the rear bumper. Called fifth wheels, these trailers are commonly used to transport large animals or flatbed units. Each state has its own regulations for these types of trailers; however, the U.S. Department of Transportation also has laws covering gooseneck trailers.

Coupling Device

By design, coupling devices for gooseneck trailers must tow the trailer in a straight line when on a flat, paved surface. The path of the trailer cannot deviate from the vehicle towing the trailer by more than 3 inches. A fifth wheel assembly should be secured to the frame of the vehicle in a way that does not adversely affect the frame and must not shift during towing. The device must incorporate a locking mechanism with a manual method of unlocking. Fifth wheel devices must evenly distribute the weight of the gooseneck trailer over its axles and the axles of the towing vehicle. Fifth wheel assemblies must not cause instability in the towing vehicle's steering, braking or other operating capability.

Brake System

Gooseneck trailer braking methods often depend on the type of load you are hauling. Most states require a separate braking system for trailers with a loaded weight of more than 1,500 pounds. An emergency breakaway switch is required to activate the trailer brakes automatically should the trailer and towing vehicle become separated. If electronic brakes are used, the towing vehicle must have a control unit near the driver and provide brake operation either automatically or manually. Surge brakes, also called hydraulic brakes, should be independent from the braking system of the towing vehicle. Certain states require brakes on each axle of a multiple axle trailer.


Gooseneck trailers require at least two tail lamps to illuminate the vehicle. These lights must be red in color and be mounted on the rear of the trailer, as far apart as possible. Two red brake lights are required on the rear of the unit to indicate brake activation. At least two turn signal lamps at the rear must indicate the direction of a turn and can be red or yellow in color. Left and right red side marker lights must be mounted as far to the rear as practical. Red reflectors should be placed on the rear of the trailer, as far apart as possible, to mark the trailer's width. Similar reflectors must be on each side of the trailer, at the rear, and indicate length. Yellow front sidelights are required on both sides and should be mounted as far forward on the trailer as possible. Yellow front side reflectors must be placed on each side of the trailer, as far forward as possible. Trailers measuring 30 feet or longer require additional yellow sidelights and reflectors mounted near the center of the unit. The license plate holder also must be illuminated with a white light. Gooseneck trailers that are 80 inches or wider, and have a gross vehicle weight of 10,000 pounds or more, must have red and white side markings on all sides. This marking is usually reflective tape that must run over at least 50 percent of the trailer's length.

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