Why Trailer Type Matters in Heavy Haul
In standard freight, trailer selection is mostly about cargo volume and weight. In heavy haul, trailer selection also directly controls the total height of the load on the road — which determines whether you need oversize permits, what routes are legally available, and what escort requirements apply. The wrong trailer doesn't just add cost; it can make a legally permitted move impossible.
R&RM LLC has been matching trailer types to loads since 2011, moving excavators, cranes, bulldozers, transformers, and industrial machinery across all 48 continental states. Understanding the key differences between trailer types helps shippers ask the right questions, set accurate expectations, and avoid surprises when the carrier arrives for pickup.
The Four Primary Trailer Types in Heavy Haul
Standard Flatbed Trailer
A standard flatbed is a flat, open deck with no sides or roof, mounted to a fixed gooseneck that connects to the tractor's fifth wheel. The deck sits approximately 58 inches (4 feet 10 inches) off the ground. A standard flatbed typically measures 48 or 53 feet in length and handles loads up to approximately 48,000 lbs with a standard 3-axle configuration.
The defining limitation of a standard flatbed in heavy equipment contexts is deck height. When a piece of equipment sits on a 58-inch deck, its own height is added on top. The legal maximum height on most US highways is 13 feet 6 inches. A mini excavator that stands 9 feet 0 inches tall at the cab roof, placed on a 58-inch (4.8-foot) deck, puts the top of the cab at roughly 13.8 feet — already over the legal limit before accounting for any raised attachments.
This is why standard flatbeds are used in heavy haul primarily for compact equipment, detached components, and loads that can be crane-placed to precise positions. Equipment that can be loaded by forklift or crane, is not excessively tall, and fits the flatbed's weight and dimension limits can move on a flatbed without oversize permits in many states. Equipment that drives itself onto the trailer — or that is too tall at flatbed deck height — cannot.
Step-Deck (Drop-Deck) Trailer
A step-deck trailer has two deck levels: a raised upper deck behind the gooseneck (sitting at approximately 58 inches), and a lower main deck that drops to approximately 34 inches off the ground. The step eliminates the height needed to clear the rear tandem axles, which is what keeps the standard flatbed deck high. The lower main deck gives equipment roughly 2 feet of additional height clearance compared to a standard flatbed.
Step-decks are common for equipment that is too tall for a standard flatbed but does not require drive-on loading. Agricultural equipment, some telehandlers, wide utility vehicles, and industrial components that can be crane-loaded often travel on step-decks. Like standard flatbeds, step-decks require crane or forklift loading — there is no ramp capability.
RGN (Removable Gooseneck) Trailer
The RGN is the workhorse trailer for construction, agricultural, and mining equipment transport. The front gooseneck section — which connects the trailer to the tractor — is removable. When detached, the trailer deck angles down to ground level, creating a ramp that self-propelled equipment can drive directly onto. After loading, the gooseneck reattaches and locks into place, securing the load for transport.
RGN deck height in the transport position is typically 18 to 22 inches off the ground — significantly lower than a flatbed's 58 inches. This lower deck allows taller equipment to stay within legal height limits. An excavator that stands 10 feet tall, placed on an 18-inch deck, reaches roughly 11 feet 6 inches — comfortably below the 13 ft 6 in legal limit in most states.
RGN trailers come in a range of configurations:
- 3-axle RGN: The standard configuration. Handles loads up to approximately 40,000–45,000 lbs net cargo. Total GVW typically around 80,000 lbs.
- 4-axle and 5-axle RGN: Additional axles spread weight across more contact points. Handles loads in the 60,000–80,000 lb net range with appropriate overweight permits.
- Multi-axle (6+ axles): For the heaviest loads. A 13-axle configuration can move loads exceeding 300,000 lbs on permitted routes.
- Stretch RGN: The deck length extends to accommodate longer loads — bridge beams, long crane boom sections, or oversized industrial components that exceed standard RGN lengths of 24–29 feet.
RGN hauling is R&RM LLC's most frequently used trailer type for equipment transport. If your load drives under its own power, an RGN is almost certainly the right choice.
Lowboy Trailer (Fixed-Neck)
A lowboy trailer achieves a low deck profile similar to an RGN but uses a fixed gooseneck rather than a removable one. Because the gooseneck does not detach, the trailer cannot ramp down to ground level — loading requires a crane, a forklift, or a ramped loading area such as a loading dock or earthen ramp.
Lowboy deck height is typically 16 to 18 inches, similar to an RGN. The tradeoff is loading method: what an RGN loads by drive-on in 20–30 minutes, a lowboy may take 1–2 hours with crane rigging. For equipment that cannot drive under its own power — certain cranes, large generators, tall industrial components — the lowboy is appropriate. For anything that can drive, the RGN's speed and simplicity wins.
Hydraulic Platform (Goldhofer) Trailers
For loads exceeding what even a multi-axle RGN can handle — typically above 200,000–300,000 lbs — hydraulic modular trailers (often called Goldhofers after a major manufacturer) are used. These self-propelled or towed platforms can be assembled to virtually any length and width, with independently steerable axle rows that allow the trailer to articulate through tight turns. Hydraulic suspension keeps the load level regardless of road surface variations.
Goldhofer moves are superloads by definition and require weeks of permit lead time, engineering analysis, and often law enforcement escorts rather than private pilot cars. Large power transformers, nuclear reactor components, and the heaviest industrial machinery move on hydraulic platform trailers.
RGN vs Flatbed: The Decision Framework
In most heavy haul situations, the choice between an RGN and a flatbed comes down to three factors: height, loading method, and weight.
Height: The Primary Decision Driver
Calculate the expected total height of your load on each trailer type. The legal limit in most states is 13 ft 6 in (some allow up to 14 ft without a permit). If placing your equipment on a standard flatbed deck (58 inches above ground) pushes total height over 13 ft 6 in, you need a lower-profile trailer.
Equipment height thresholds at common deck heights:
- Standard flatbed (58-inch deck): Equipment must be no taller than approximately 8 ft 10 in to stay under 13 ft 6 in total height
- Step-deck (34-inch deck): Equipment must be no taller than approximately 10 ft 8 in
- RGN/Lowboy (18-inch deck): Equipment must be no taller than approximately 12 ft 0 in
Most full-size construction equipment — standard excavators, bulldozers, motor graders, wheel loaders — stands between 10 and 13 feet tall. That puts them in RGN or lowboy territory for virtually every move.
Loading Method: Drive-On vs Crane
If the equipment cannot be crane-loaded — because it lacks proper lift points, is too heavy for available cranes, or because no crane is available at the pickup site — an RGN is the practical choice. The drive-on ramp is faster, less expensive than crane rental, and does not require a separate crane crew or rigging equipment.
If the equipment has no ability to drive under its own power — non-operational equipment awaiting repair, equipment disassembled for transport, or fixed components like steel beams — crane loading onto a flatbed, step-deck, or lowboy is the standard approach. In these cases, the trailer type is determined by height and weight, not by loading method.
Weight: How Much Your Load Weighs
Standard flatbeds cap out around 48,000 lbs net cargo with a standard axle configuration. Beyond that, you're in overweight permit territory regardless of trailer type. An RGN with additional axles can legally carry far more weight with the appropriate permits.
A typical loaded excavator weighs 40,000 to 200,000 lbs depending on size class. Even the smallest full-size excavators push the upper limit of a standard flatbed's weight capacity — and their height makes a standard flatbed impractical anyway. The combination of height and weight considerations means excavators, dozers, and most construction equipment go on RGN trailers as a matter of course.
Equipment Types and Which Trailer They Use
Excavators
RGN trailers are the near-universal choice for excavator transport. The excavator's cab height (typically 10–12 feet in travel position), combined with the ability to drive onto the trailer under its own power, makes the RGN the only practical option in most cases. The boom is lowered and pinned in the travel position; the bucket may be removed to reduce weight and minimize height and length oversize. A 3-axle or 5-axle RGN handles most excavators from the 20-ton to 50-ton class. Larger excavators in the 80- to 120-ton range require multi-axle configurations and overweight permits.
Bulldozers
RGN trailers are standard for dozer transport. The blade is typically removed or reversed to reduce length and width, and the dozer drives onto the RGN deck. Large bulldozers in the D9 and D11 class can approach or exceed 100,000 lbs, requiring multi-axle RGN configurations and overweight permits. The ripper assembly at the rear of the dozer may also need to be removed or pinned to reduce overhang.
Motor Graders
Motor graders are typically RGN loads due to their height and weight. The articulated frame and blade extend the length and width of the load. Most motor graders in the 140M–16M class weigh 30,000–55,000 lbs and are slightly oversize in width, requiring oversize permits. They drive onto the RGN under their own power.
Wheel Loaders
Mid-size and large wheel loaders are RGN loads. Compact wheel loaders under 25,000 lbs may move on step-decks or flatbeds if their height permits. Large loaders in the L60–L350 class are full oversize/overweight RGN moves. Bucket removal is common to reduce height and length.
Cranes
Crane transport is among the most complex in heavy haul. The crane's main body (car body and superstructure) typically moves on a lowboy or RGN depending on its drive configuration. Boom sections, counterweights, and outrigger pads often move separately as flatbed loads. A large lattice-boom crawler crane may require 10 or more separate loads, each with its own permit package.
Compact and Mini Equipment
Mini excavators (under 10,000 lbs), compact track loaders, small skid steers, and similar equipment can often move on standard flatbeds or step-decks, particularly when the shipper has crane or forklift access at the pickup site. Their weights and heights are within flatbed limits, and their smaller dimensions frequently keep them below oversize width thresholds. These moves often do not require oversize permits at all.
Agricultural Equipment
Combines, large tractors, and harvest equipment are almost always RGN loads. Combine headers are typically separated and loaded as a second load due to their extreme width (20 feet or more with platforms installed). The combine main body travels on an RGN and typically requires oversize permits for width in most states. Farm equipment hauling from R&RM LLC covers both the main machine and implement loads.
Power Transformers and Industrial Equipment
Power transformers and large industrial equipment — pressure vessels, heat exchangers, reactor units — are typically lowboy or hydraulic platform loads because they cannot drive under their own power. Their weights (50,000 to 500,000 lbs) and dimensions determine whether a standard lowboy or a Goldhofer-type hydraulic platform is required. These are nearly always overweight permit moves, often qualifying as superloads.
Cost Comparison: RGN vs Flatbed
RGN trailers cost more per mile to operate than standard flatbeds due to their specialized equipment, higher capital cost, and greater maintenance requirements. The gooseneck detachment mechanism, the heavy-duty deck structure, and the additional axle sets (for multi-axle configurations) all add cost. When oversize permits are required — which they often are for RGN loads — permit fees, pilot car costs, and the time required to obtain permits also add to the total move cost.
A standard flatbed move for light equipment is typically the least expensive option per mile. But if the flatbed is the wrong trailer for the load, the comparison is moot — you need the right equipment for the job. Attempting to cut costs by using an undersized or incorrect trailer risks load damage, permit violations, and fines that far exceed any savings on the trailer rate.
When requesting a quote from R&RM LLC, provide accurate equipment dimensions and weight so we can identify the correct trailer configuration and provide an accurate permit cost estimate. Call us at (404) 987-6225 or submit your load details online for a detailed quote.
How to Determine Which Trailer You Need
When planning a heavy equipment transport, work through these questions in order:
- Can the equipment move under its own power? If yes, an RGN is the likely trailer — its drive-on capability is irreplaceable for self-propelled equipment. If no, continue to the next question.
- What is the total height of the load at each deck height? Calculate: load height + trailer deck height. If the total exceeds 13 ft 6 in on a standard flatbed, step up to a step-deck or RGN/lowboy.
- What is the weight of the load? Above approximately 48,000 lbs net cargo, a standard flatbed is typically out. RGN or lowboy with additional axles, combined with overweight permits, handles the weight.
- What is the width of the load? Loads wider than 8 ft 6 in require oversize permits regardless of trailer type. The trailer type doesn't affect the width permit requirement, but it does affect how you load and transport the machine.
- Is crane access available at pickup and delivery? If crane loading is not available, an RGN (drive-on) is the practical solution.
R&RM LLC's dispatch team walks through these questions with every shipper before booking a move. Providing accurate dimensions and confirming the equipment's operational status at the time of inquiry allows us to spec the right trailer and provide an accurate permit cost on the first quote. Our permit services team handles all applications regardless of how many states the move crosses.
Frequently Asked Questions
What is the main difference between an RGN and a flatbed trailer?
An RGN (Removable Gooseneck) trailer has a detachable front section that allows the deck to angle down to ground level, creating a drive-on ramp for self-propelled equipment. A standard flatbed has a fixed deck approximately 58 inches off the ground and requires crane or forklift loading. The RGN's drop-to-grade capability is the critical feature for excavators, bulldozers, and other heavy equipment that moves under its own power.
Can a flatbed haul equipment that's over 80,000 lbs?
A standard flatbed is limited to approximately 48,000 lbs of net cargo with a standard 3-axle configuration. Equipment weighing more than this requires an RGN, lowboy, or multi-axle trailer combined with overweight permits. These specialized trailers distribute weight across additional axles to bring per-axle weights into compliance while still allowing total gross vehicle weights well above 80,000 lbs.
What equipment requires an RGN instead of a flatbed?
Any self-propelled equipment that is too tall, too heavy, or cannot be crane-loaded typically requires an RGN. Full-size excavators, bulldozers, wheel loaders, motor graders, and large agricultural machinery are standard RGN candidates. Equipment that stands over approximately 8 feet 10 inches tall will exceed 13 ft 6 in legal height when placed on a flatbed deck — making an RGN or lowboy mandatory.
When is a flatbed appropriate for heavy equipment?
Flatbeds are appropriate for compact or light equipment that can be crane-loaded, is not excessively tall, and does not exceed the flatbed's weight capacity. Mini excavators, compact track loaders, small skid steers, and detached components (dozer blades, bucket assemblies, crane boom sections) can often travel on flatbeds. Their smaller dimensions may also keep them below oversize width thresholds, eliminating permit requirements entirely.