Flatbed vs. Step Deck vs. Lowboy vs. RGN: Choosing the Right Trailer for Heavy Equipment
Choosing the wrong trailer for a heavy equipment move can mean permit violations, loading failures, or equipment damage. The four main trailer types used in heavy haul — flatbed, step deck, lowboy, and RGN — each have specific strengths, limitations, and use cases. This guide explains exactly when to use each one, with real dimensions, weight limits, and practical examples.
The Four Main Heavy Haul Trailer Types
Before diving into selection criteria, here is a quick overview of each trailer type:
| Trailer Type | Deck Height | Max Legal Cargo Height | Max Payload | Loading Method |
|---|---|---|---|---|
| Flatbed | ~60 in (5 ft) | ~8 ft 6 in | 48,000 lbs | Crane, forklift, or side-load |
| Step Deck (Drop Deck) | ~36 - 42 in (lower deck) | ~10 ft 2 in | 48,000 lbs | Crane, forklift, or rear ramp |
| Lowboy (Double Drop) | ~18 - 24 in | ~11 ft 6 in - 12 ft | 40,000 - 80,000 lbs | Rear ramp or detachable neck |
| RGN (Removable Gooseneck) | ~18 - 24 in | ~11 ft 6 in - 12 ft | 40,000 - 150,000+ lbs | Drive-on (front ramp via detached neck) |
When to Use a Flatbed
A standard flatbed trailer is the right choice when your equipment is within legal height limits (under 8 ft 6 in tall when loaded on the trailer), can be loaded by crane, forklift, or side-loading, and weighs under 48,000 lbs.
Common examples: Small skid steers, compact forklifts, attachments (buckets, blades), generators under 10,000 lbs, small compressors, and palletized machinery.
Flatbeds are the most widely available and least expensive trailer type. If your equipment fits within legal limits, a flatbed is almost always the most cost-effective choice.
When to Use a Step Deck (Drop Deck)
A step deck is the right choice when your equipment is taller than 8 ft 6 in but under approximately 10 ft 2 in when loaded, can be loaded by crane, forklift, or rear ramp (not drive-on), and weighs under 48,000 lbs.
Common examples: Mid-size skid steers, telehandlers, compact excavators, scissor lifts, boom lifts, and medium-size forklifts.
The step deck's lower main deck (36 to 42 inches off the ground vs. 60 inches for a standard flatbed) provides 18 to 24 inches of additional height clearance. This is often enough to keep a mid-size machine within legal limits without needing a height permit.
When to Use a Lowboy
A lowboy is the right choice when your equipment is taller than 10 ft 2 in but under approximately 11 ft 6 in to 12 ft when loaded, is non-operable or cannot drive onto the trailer, and weighs between 40,000 and 80,000 lbs.
Common examples: Large excavators (non-operable), tall cranes (disassembled), industrial generators, large compressors, and tall construction equipment that cannot drive onto an RGN.
Lowboys provide the same low deck height as RGNs but without the drive-on capability. They are the right choice when you need maximum height clearance but the machine cannot drive onto the trailer under its own power.
When to Use an RGN (Removable Gooseneck)
An RGN is the right choice when your equipment is self-propelled and can drive onto the trailer, is taller than 10 ft 2 in when loaded on a step deck, and weighs between 40,000 and 150,000+ lbs (depending on axle configuration).
Common examples: Excavators, bulldozers, motor graders, wheel loaders, pavers, compactors, and any other tracked or wheeled equipment that can drive under its own power.
The RGN's defining feature is the detachable front gooseneck, which drops to ground level and forms a ramp. This allows the equipment operator to drive the machine directly onto the trailer — no crane or forklift needed. This is a major advantage at remote job sites or auction yards where lifting equipment may not be available.
The Height Calculation: How to Determine Which Trailer You Need
The key calculation is: Trailer deck height + Equipment height = Total loaded height
Compare this to the 13 ft 6 in federal legal limit (and state-specific limits, which vary):
- Flatbed deck: approximately 60 in (5 ft). Equipment must be under 8 ft 6 in tall to stay legal.
- Step deck lower deck: approximately 36 to 42 in (3 to 3.5 ft). Equipment must be under 10 to 10.5 ft tall to stay legal.
- Lowboy/RGN deck: approximately 18 to 24 in (1.5 to 2 ft). Equipment must be under 11.5 to 12 ft tall to stay legal.
If your equipment exceeds 12 ft tall even on a lowboy or RGN, you will need an oversize height permit regardless of trailer type. At that point, the focus shifts to route planning to avoid low clearances.
Cost Comparison
Trailer type significantly affects shipping cost:
- Flatbed: Most affordable; widest carrier availability
- Step deck: Slightly more than flatbed; still widely available
- Lowboy: 20 to 40% more than flatbed; more specialized equipment
- RGN: 30 to 50% more than flatbed; most specialized; highest demand during construction season
IronHaul Logistics operates flatbeds, step decks, lowboys, and RGNs for heavy equipment moves nationwide. Call (208) 495-2260, email [email protected], or use our online quote form — we will recommend the right trailer for your specific machine and route.
Common questions
What is the difference between a lowboy and an RGN trailer?
Both lowboys and RGNs have a low deck height (18 to 24 inches) that provides maximum height clearance for tall equipment. The key difference is loading method: an RGN has a detachable front gooseneck that drops to ground level, allowing self-propelled equipment to drive directly onto the trailer. A lowboy uses rear ramps or a detachable neck for loading and is better suited for non-operable equipment.
How do I know if my equipment needs a step deck or a lowboy?
Calculate the total loaded height: trailer deck height plus equipment height. A step deck's lower deck is about 36 to 42 inches off the ground, giving you roughly 10 to 10.5 ft of cargo height before hitting the 13 ft 6 in legal limit. If your equipment is taller than that, you need a lowboy or RGN (deck height 18 to 24 inches), which gives you up to 11.5 to 12 ft of cargo height.
Can any equipment drive onto an RGN trailer?
Only self-propelled equipment that can drive, steer, and brake under its own power can use the drive-on loading method of an RGN. Non-operable equipment must be winched or crane-loaded onto the trailer, which adds cost and time. Confirm your machine's operability status when booking transport.
Which trailer type is most expensive for heavy equipment shipping?
RGN trailers are typically the most expensive, running 30 to 50% more than a standard flatbed due to their specialized design and high demand during construction season. Lowboys are 20 to 40% more than flatbeds. Step decks are only slightly more expensive than flatbeds and are widely available.
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