Heavy Hauling

Heavy hauling is the transport of loads that are unusually heavy, large or both, such as construction and agricultural machinery, generators, transformers, industrial equipment, steel beams and other oversized freight. It usually requires open-deck trailers that can be loaded by crane, forklift or ramp, and it often involves careful planning around legal size and weight limits. Loads that exceed those limits need permits from each state on the route and sometimes escort vehicles. Heavy hauling ranges from a hot shot carrying a heavy machine part to specialized trailers moving equipment weighing many tons.

An oversize load is freight whose dimensions exceed the legal limits for width, height or length on the roads it will travel. The standard legal width in the United States is 8.5 ft, or 102 inches, while height and length limits are set by each state, with 13.6 ft a common height limit. Oversize loads need a permit from every state on the route, display banners, flags and lights, and may need pilot cars and route surveys. Many states also restrict when oversize loads can travel, such as daylight hours only or no weekend travel.

An overweight load is one whose total weight or axle weights exceed the legal limits. On the Interstate system, the federal limits are 80,000 lbs gross vehicle weight, 20,000 lbs on a single axle and 34,000 lbs on a tandem axle group, with a bridge formula limiting weight on closely spaced axles. A load over these limits needs an overweight permit from each state on the route, and the permit may specify the route, the axle configuration and travel times. Heavier loads often move on trailers with more axles to spread the weight within allowed limits.

On the Interstate highway system, the federal gross vehicle weight limit for a commercial truck and its load is 80,000 lbs. Federal rules also limit a single axle to 20,000 lbs and a tandem axle group to 34,000 lbs, and the bridge formula limits how much weight can be carried on groups of axles based on how far apart they are. States can set their own limits on other roads and may allow higher weights under specific permits or grandfathered rules. Loads that would exceed these limits need overweight permits before they travel.

A pilot car, also called an escort vehicle, is a vehicle that travels with an oversize load to warn other drivers and help the truck navigate safely. Pilot cars may drive ahead of the load, behind it or both, depending on the load's size and the state's rules. They carry signs and lights, communicate with the truck driver by radio and help with turns, low clearances and traffic. Each state sets its own requirements for when pilot cars are needed and how many, usually based on the load's width, height and length.

A step deck trailer, sometimes called a drop deck, is an open trailer with an upper deck at the front and a lower main deck behind it. The lower deck sits closer to the ground than a standard flatbed, which gives taller freight extra height clearance. This often allows loads that would be too tall on a flatbed to stay within legal height without a permit. Step decks are used for machinery, equipment and tall industrial freight. Loading usually happens by crane or forklift, and some step decks use ramps so equipment can be driven on.

A removable gooseneck trailer, often called an RGN, is a heavy haul trailer whose front section detaches from the deck. When the gooseneck is removed, the front of the trailer lowers to the ground and forms a ramp, so tracked or wheeled machinery such as excavators and dozers can drive straight onto the deck. RGN trailers have a low deck height, which helps tall equipment stay within height limits. They are widely used for construction and industrial machinery and are operated by specialized heavy haul carriers, often with permits for the heaviest loads.

A lowboy is a heavy haul trailer with a deck that sits very close to the ground, usually dropping down between the gooseneck and the rear axles. The low deck gives the most height clearance of any common trailer, which makes it suitable for very tall and heavy machinery and industrial equipment. Many lowboys have removable goosenecks for drive-on loading and multiple axles to spread heavy weight. Loads on lowboys often exceed standard limits and need permits, route planning and sometimes escorts. They are operated by specialized heavy haul carriers.

The federal bridge formula is a rule that limits how much weight a truck can carry on any group of axles based on the number of axles and the distance between them. It exists to protect bridges, which can be damaged when heavy weight is concentrated over a short span. Under the formula, spreading axles farther apart allows more weight to be carried legally. For heavy hauling, it explains why heavier loads often move on longer trailers with more axles, and why the axle layout of a truck matters as much as the total weight of the load.

Load securement is the practice of fastening cargo to a truck or trailer so it cannot shift, fall or come loose during transport. For heavy freight it usually involves chains and binders or straps with a combined working load limit suited to the cargo's weight, plus edge protection, blocking and bracing. Federal rules set minimum securement requirements, including the number of tie-downs based on the cargo's length and weight. Drivers are expected to inspect securement before departure and at intervals during the trip. Proper securement protects the freight, the truck and other road users.