Flatbed, step deck or RGN?
Nearly every open-deck quote that goes wrong goes wrong for the same reason: somebody guessed the height. The trailer you need is decided by one number, and this is how to work out which one it is before you make the call.
What is the difference between a flatbed, a step deck and an RGN?
Deck height is the difference. A flatbed deck sits about sixty inches high and takes freight up to roughly eight feet six inches tall. A step deck drops to about forty inches and takes about ten feet. An RGN lowboy drops to about eighteen inches in the well and takes about eleven feet six inches.
Legal height is 13 feet 6 inches. Work backwards.
In most states a loaded truck may be up to thirteen feet six inches tall before it needs a permit. Subtract the deck height from that and you have the tallest freight the trailer can legally carry. That subtraction is the entire decision.
| Trailer | Deck height | Max legal freight height | Typical payload | What rides on it |
|---|---|---|---|---|
| Flatbed | about 60 in | about 8 ft 6 in | up to about 48,000 lb | Steel, lumber, pipe, crates, packaged building products |
| Step deck | about 40 in (lower deck) | about 10 ft | up to about 48,000 lb | Machinery, tall crates, small tracked equipment |
| Double drop | about 24 in (well) | about 11 ft 6 in | about 40,000 lb | Tall machinery that still loads by crane |
| RGN lowboy | about 18 in (well) | about 11 ft 6 in | 40,000 lb and far more on multi-axle | Excavators, dozers, loaders — anything that drives on |
The RGN earns its keep on a second count as well as height: the gooseneck detaches and the front of the trailer drops to the ground, making a ramp. Tracked equipment drives on under its own power instead of being craned. For a dozer or an excavator that is not a convenience, it is the only practical method.
Before you ask anyone for a price.
- 01
Height
From the ground the item will sit on, to its highest point, including anything folded down. Measure it. Do not read it off a brochure, because the brochure does not know what tyres are on it.
- 02
Width
At the widest point, including mirrors, buckets, tracks and any overhang. Anything over eight feet six inches is a permit load in most states.
- 03
Length
Overall, including anything that projects fore or aft.
- 04
Weight
Actual operating weight, including attachments, fuel and ballast. An excavator with a hammer instead of a bucket is a different load.
Send a photograph as well. A photograph tells an experienced dispatcher things four numbers cannot: where the tie-down points are, whether the tracks will clear the wheel wells, and whether the machine will actually make the ramp angle.
Any one of these, and it changes.
- Over 8 ft 6 in wide — oversize permit, and possibly escorts.
- Over 13 ft 6 in tall — permit plus a route survey for bridges.
- Over 80,000 lb gross — overweight permit and often an axle configuration study.
- Over about 53 ft of load length — overlength permit and rear escort.
- Crossing state lines — a permit per state, each with its own rules and travel windows.
- Night or weekend movement — many permits forbid it outright.
The permit is not the slow part; the route survey is. An oversize move across three states can need bridge analysis, utility notification and police escorts scheduled around each state's permitted travel hours. Budget days, not hours, and start the conversation before the equipment is sold rather than after.
Straight answers
How tall can a load be without a permit?
Thirteen feet six inches overall in most states, measured from the road surface to the top of the load. Subtract the trailer's deck height to get the freight height the trailer can carry.
How much weight can a flatbed carry?
About forty-eight thousand pounds of freight, working back from the eighty-thousand-pound federal gross limit after the tractor and trailer are accounted for. Multi-axle heavy-haul configurations go far beyond that, with permits.
Do I need a step deck or a flatbed?
Measure the height. If the freight is under about eight feet six inches, a flatbed works and is cheaper and more available. Above that and up to about ten feet, you need the step deck's lower deck.
Can an excavator go on a step deck?
A small one, sometimes. Anything sizeable needs the RGN, both for the height and because the removable gooseneck makes a ramp the machine can drive up. Send the operating weight and the transport height.
Read next
Flatbed
Flatbed capacity out of Spartanburg for steel, lumber, building products and machinery: securement-trained drivers, tarps, chains and edge protection, on the I-85 and I-20 corridors.
Read onStep deck
Step deck and flatbed capacity for machinery, steel, lumber and building products, with securement-trained drivers, tarps and permits handled.
Read onHeavy haul & oversize
RGN lowboy capacity for heavy equipment and oversize loads: permits, route survey, escorts and securement, out of Spartanburg across the Southeast, South and Midwest.
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