Step-Deck vs. Lowboy vs. RGN: Choosing the Right Trailer for Heavy Equipment
When you're shipping heavy equipment, the trailer type determines whether your load is legal, safe, and cost-effective. Step decks, lowboys, and RGN (Removable Gooseneck) trailers each serve different equipment profiles — and choosing the wrong one can mean a rejected load, a permit violation, or equipment damage. This guide explains the practical differences between these three trailer types and helps you identify which one your equipment needs.
Why Trailer Selection Matters
The three most common open-deck trailer types for heavy equipment — step deck, lowboy, and RGN — differ primarily in deck height, weight capacity, and loading method. Deck height determines how tall your equipment can be while staying within the 13 ft 6 in federal height limit (or state-specific limits). Weight capacity determines whether the trailer can legally carry your equipment's weight. Loading method determines whether your equipment needs to be driven on, craned on, or forklift-loaded. Getting these three factors right is the foundation of a successful heavy haul move.
Standard Flatbed: The Baseline
Before comparing the three specialized trailer types, it helps to understand the standard flatbed as a baseline. A standard flatbed trailer has a deck height of approximately 60 inches (5 feet) off the ground. With the federal height limit of 13 ft 6 in (162 inches), that leaves approximately 102 inches (8.5 feet) of usable height for cargo. Equipment taller than 8.5 feet on a standard flatbed will exceed the height limit and require a permit — or a different trailer type.
Step Deck (Drop Deck) Trailers
A step deck trailer has two deck levels: a higher front section (approximately 60 inches off the ground, same as a flatbed) and a lower rear section (approximately 36 inches off the ground). The lower rear deck provides approximately 18–24 inches of additional height clearance compared to a standard flatbed.
- Deck height (lower section): ~36 inches (3 feet) off the ground
- Usable height (lower section): ~126 inches (10.5 feet) before exceeding 13 ft 6 in limit
- Weight capacity: Typically 48,000 lbs on the lower deck
- Loading method: Ramps, forklift, or crane. Equipment cannot be driven on at ground level.
- Best for: Equipment 9–10.5 ft tall and under 48,000 lbs — telehandlers, compact track loaders, mid-size excavators, forklifts, generators
Lowboy (Double Drop) Trailers
A lowboy trailer has a very low center deck section — approximately 18–24 inches off the ground — achieved by dropping the deck between the front and rear axle groups. This provides significantly more height clearance than a step deck.
- Deck height (center section): ~18–24 inches off the ground
- Usable height (center section): ~138–144 inches (11.5–12 feet) before exceeding 13 ft 6 in limit
- Weight capacity: Typically 40,000–80,000 lbs on a standard lowboy configuration
- Loading method: Ramps at the rear, or crane. Equipment must be able to drive up ramps or be craned on.
- Best for: Equipment 10–12 ft tall and up to 80,000 lbs — bulldozers, motor graders, large excavators, compactors, large forklifts
RGN (Removable Gooseneck) Trailers
An RGN trailer is similar to a lowboy in deck height, but with a critical difference: the front gooseneck section is removable. When the gooseneck is detached, the front of the trailer drops to the ground, creating a ramp that allows equipment to be driven directly onto the trailer at ground level — no ramps required.
- Deck height: ~18–20 inches off the ground (same as lowboy)
- Usable height: ~138–144 inches (11.5–12 feet) before exceeding 13 ft 6 in limit
- Weight capacity: Standard RGN: 40,000–80,000 lbs. Multi-axle RGN: 100,000–150,000+ lbs
- Loading method: Equipment is driven on at ground level after gooseneck is removed. No ramps needed.
- Best for: Equipment that cannot be driven up ramps (low ground clearance, crawler tracks, large cranes), very heavy equipment over 80,000 lbs, and any equipment where ground-level loading is safer or faster
Quick Comparison Table
| Feature | Step Deck | Lowboy | RGN |
|---|---|---|---|
| Deck Height | ~36 in | ~18–24 in | ~18–20 in |
| Max Cargo Height | ~10.5 ft | ~12 ft | ~12 ft |
| Typical Capacity | 48,000 lbs | 40,000–80,000 lbs | 40,000–150,000+ lbs |
| Loading Method | Ramps/crane/forklift | Ramps/crane | Drive-on (ground level) |
| Best For | 9–10.5 ft tall equipment | 10–12 ft tall equipment | Crawlers, heavy loads, low-clearance machines |
When to Use Each Trailer Type
Use a step deck when: Your equipment is 9–10.5 ft tall, under 48,000 lbs, and can be loaded via ramps or forklift. Step decks are the most economical option for equipment that fits within their capacity.
Use a lowboy when: Your equipment is 10–12 ft tall, up to 80,000 lbs, and can be driven up ramps or craned on. Lowboys are the standard choice for most construction equipment — bulldozers, excavators, motor graders, and compactors.
Use an RGN when: Your equipment cannot be driven up ramps (crawler tracks, low ground clearance), is over 80,000 lbs, or when ground-level loading is required for safety or efficiency. RGNs are the most versatile option for heavy, oversized, or difficult-to-load equipment.
Not sure which trailer your equipment needs? IronHaul Logistics will assess your equipment's dimensions and weight and recommend the right trailer for your move. Request a free quote at ironhaullogistics.com, call (208) 495-2260, or email [email protected].
Common questions
What is the maximum height for equipment on a lowboy trailer?
A standard lowboy has a deck height of approximately 18–24 inches off the ground. With the federal height limit of 13 ft 6 in (162 inches), that leaves approximately 11.5–12 feet of usable height for cargo. Equipment taller than 12 feet on a lowboy will require a height permit.
Can a bulldozer be shipped on a step deck trailer?
Most bulldozers are too tall and too heavy for a step deck. A D6-class dozer is typically 10–11 ft tall and 40,000–50,000 lbs — at the upper limit of step deck capacity. Most carriers use a lowboy or RGN for bulldozers to provide adequate height clearance and weight capacity.
What is the difference between a lowboy and an RGN trailer?
Both have similar deck heights (~18–24 inches off the ground), but an RGN has a removable front gooseneck that drops to the ground, allowing equipment to be driven on at ground level. A lowboy requires equipment to be driven up ramps or craned on. RGNs are preferred for equipment that cannot navigate ramps.
How much weight can an RGN trailer carry?
A standard RGN carries 40,000–80,000 lbs. Multi-axle RGN configurations (adding additional axle groups) can handle 100,000–150,000+ lbs. The specific capacity depends on the number of axles and the trailer's rating.
Is a step deck cheaper than a lowboy or RGN?
Generally yes. Step decks are more common and less specialized than lowboys and RGNs, so they typically command lower rates. However, if your equipment requires a lowboy or RGN for height or loading reasons, using a step deck is not an option — the right trailer for the load is always the priority.
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