Top Heavy Haul Trailer Types Used in Specialized Freight Transport

The most common trailer types used for heavy haul transport include flatbeds, step decks, double drop decks, lowboys, and removable gooseneck (RGN) trailers. Each is designed to carry oversized freight with different dimensions and weights. Choosing the right trailer depends on your cargo’s size, shape, and specific loading needs.

What Is Heavy Haul Transportation?

Heavy haul transportation refers to the movement of oversized or overweight cargo that exceeds standard legal limits. These limits vary slightly by state, but typically include:

• Width: Over 8.5 feet
• Height: Over 13.5 feet
• Length: Over 48–53 feet
• Weight: Over 80,000 lbs gross vehicle weight (GVW)

If your oversize load is outside these standard dimensions or weights, it’s considered oversized or overweight. Therefore, it must be moved on a heavy haul trailer with the correct permits.

Learn more from the Federal Highway Administration on legal size and weight limits.

Common types of freight that fall into the oversized load category include:

• Construction equipment (excavators, loaders, cranes)
• Steel beams and structural components
• Generators, transformers, and turbines
• Agricultural machinery (combines, tractors)
• Pre-fabricated building materials
• Mining equipment (drill rigs, haul trucks, crushers)
• Wind energy components (blades, nacelles, tower sections)
• Oil and gas equipment (frac tanks, pump skids, drilling rigs)
• Oversized storage tanks and silos
• Large HVAC units and chillers
• Industrial presses and manufacturing machinery

Factors That Determine the Right Trailer Type

Before selecting a trailer for oversized equipment, consider the following:

1. Load Dimensions

Measure your cargo’s height, width, length, and weight. This determines what type of trailer you can legally use.

2. Loading Method

Will the heavy equipment be driven onto the trailer? Will it require a crane or forklift? Certain trailer types, like removable gooseneck trailers, are designed for self-propelled machinery.

3. Weight Distribution

Heavier equipment needs to be distributed across axles correctly to avoid overloading a single point.

4. State Regulations

Each state has its own rules for permitted load sizes. Some states allow higher weights per axle or taller loads than others.

5. Permit Requirements

Oversized or overweight loads will require state-issued permits, and some may need escort vehicles or limited travel hours.

Heavy Haul Trailer Comparison Chart

Trailer Type	Best For	Max Capacity	Deck Height	Loading Style
Flatbed Trailer	Steel beams, pallets, lumber	~48,000 lbs	~5 ft	Forklift, crane
Step Deck Trailer	Taller equipment, containers	~46,000 lbs	~3.5 ft (lower deck)	Forklift, crane
Double Drop Deck Trailer	Extra tall loads like tanks or turbines	~40,000 lbs	~18–24 inches	Forklift, crane
Lowboy Trailer	Excavators, bulldozers, wheel loaders	40,000–80,000+ lbs	18–24 inches	Crane, ramps
RGN (Removable Gooseneck)	Drive-on heavy equipment	Up to 150,000+ lbs	12–24 inches	Drive-on/off
Enclosed Trailer	Weather-sensitive or valuable items	~10,000–26,000 lbs	N/A	Enclosed loading area
Utility Trailer	Small equipment or support materials	~7,000–12,000 lbs	Low open deck	Hand load, forklift

Flatbed Trailers

A flatbed trailer is an open deck trailer with no sides or roof. It’s one of the most common trailers in the trucking industry because it can carry a wide variety of loads on the flat deck that fit within legal height and width limits.

Commonly used for hauling:

• Steel beams and rebar
• Lumber and building materials
• Palletized freight
• Precast concrete products

Pros: Easy to load and unload from any side, widely available and cost-effective, works for many different cargo types.

Cons: No weather protection for cargo without additional tarping equipment, limited to legal height loads without permits.

Step Deck Trailers (Drop Deck Trailers)

Step decks provide more vertical clearance by featuring a lower deck height behind the tractor. The lower deck allows taller cargo to be hauled without exceeding height limits.

Commonly used for hauling:

• Agricultural equipment
• Rooftop HVAC units
• Tall palletized goods
• Medium-size construction equipment

Pros: Allows taller loads than a flatbed without permits, easier forklift access to lower deck, versatile for different load types.

Cons: Slightly less cargo space than a flatbed, upper deck height still limits some cargo.

Double-Drop Deck Trailers

A double drop trailer has a recessed “well” in the middle section for extra tall cargo. This design keeps the load’s center of gravity low for better stability.

Commonly used for hauling:

• Generators and turbines
• Industrial tanks
• Large construction machinery
• Tall equipment that exceeds flatbed height limits

Pros: Can carry cargo up to 11.5 feet tall without permits in some states, stable for top-heavy loads, works for both tall and moderately heavy cargo.

Cons: Limited deck space in the well, less common and typically cost more to book.

Lowboy Trailers

Lowboys are purpose-built for hauling tall, heavy machinery. With a deck that sits inches from the ground, these trailers allow the heaviest cargo to be moved safely under bridges and overpasses. They often come in fixed-neck, hydraulic, or mechanical models.

Commonly used for hauling:

• Bulldozers and excavators
• Cranes and loaders
• Heavy construction equipment
• Oversized industrial machinery

Pros: Handles very heavy loads, low deck height allows tall cargo to clear bridges, can add axles for higher weight capacity.

Cons: Requires special permits for most loads, slower loading process compared to drive-on RGNs.

Removable Gooseneck (RGN) Trailers

RGN trailers are similar to lowboys, but the gooseneck detaches, allowing equipment to be driven directly onto the trailer. It’s one of the most flexible options for hauling heavy machinery.

Commonly used for hauling:

• Excavators and dozers
• Large agricultural machinery
• Military equipment
• Construction machines with tracks or wheels

Pros: Easy drive-on and drive-off loading, can carry extremely heavy loads with extra axles, adjustable length for longer cargo.

Cons: More expensive to operate than standard trailers, requires extra space for loading and unloading.

Enclosed Trailers

An enclosed trailer has walls and a roof to protect cargo from weather and road debris. While not typically used for true heavy haul, it’s valuable for high-value or sensitive equipment.

Commonly used for hauling:

• Tools and small machinery
• Finished building materials
• Weather-sensitive equipment
• Electronics or delicate freight

Pros: Full protection from weather and theft, works for smaller but valuable items.

Cons: Limited space and cargo capacity, not suitable for oversized loads.

Permits and State Regulations

Oversized and overweight loads require permits. Here’s what you need to know:

#1 Each state has different rules.

Regulations vary from state to state. For example, California has stricter axle weight limits than Texas. Use the U.S. DOT’s State Permit Info to check the requirements for each state along your route.

#2 Permits are required for:

Loads over 8’6″ wide, loads over 13’6″ tall, or loads over 80,000 lbs GVW. Some states also have length limits that require permits.

#3 Escort vehicles may be required

Very wide or tall loads may need one or more escort vehicles to travel in front of or behind the truck for added safety.

#4 Travel times may be limited

Oversized loads may only be allowed to move during daylight hours, on certain days of the week, or outside of holidays.

What to Ask When Booking a Heavy Haul Trailer

The more details you have upfront, the easier it is to match with the right trailer and avoid costly delays. Ask yourself these questions:

1. What are the exact dimensions and weight of my cargo?
2. Is the cargo self-propelled or will it require loading equipment?
3. Will the trailer need modular axles for weight distribution?
4. Does the route include bridges or restricted roads?
5. Who secures the permits—me or the carrier?

Working With an Experienced Carrier

Mercer Transportation specializes in oversized and specialized freight services, backed by a fleet of over 1,700 trucks and access to more than 30,000 qualified carriers. With decades of experience, an industry-recognized safety record, and dedicated support for permits, route planning, and load coordination, Mercer has the resources to handle oversized cargo services.

If you need a trusted partner for your next heavy haul move, contact Mercer Transportation today and put over 40 years of proven experience to work for you.