RGN vs lowboy vs step deck: picking the deck before you measure twice

Notes from the yard — published September 3, 2026 by the dispatch desk at Long Road Transportation.

Start from the height you are allowed

Washington's statutory height limit is 14 feet, but almost every multi-state route is planned to 13 feet 6 inches, because that is what the neighbouring states and the low clearances assume. Take 13'6" as the working ceiling and the trailer choice falls out of the subtraction.

• Flatbed — deck sits around 5 feet off the ground, leaving roughly 8'6" of cargo height. Loads from any side, by crane or forklift. Steel, lumber, pipe, palletised machinery.
• Step deck — the lower deck drops to roughly 36 to 42 inches, so cargo can run about 10 feet tall. Loads by crane, forklift or ramps off the back.
• RGN — the gooseneck detaches at the front so a machine drives on from ground level into the well. Cargo of about 11'6" stays legal, and the trailer carries well past 80,000 pounds gross with the right axle configuration.

Height is the constraint. Loading method is the tie-breaker

If two trailers both clear on height, the question becomes how the cargo gets on. A step deck needs a crane, a forklift big enough for the piece, or ramps and a machine that can climb them. An RGN needs none of that: drop the neck, drive the machine into the well, reconnect.

That matters on job sites with no lifting equipment, and it matters on the return trip when a customer assumed a crane would be waiting and it is not. We have moved plenty of loads onto an RGN purely because the receiving end had nothing to lift with.

Lowboy and RGN: the same trailer, two ways of loading

"Lowboy" is a class of trailer, not one model. It means any trailer with the deck dropped into a well between the gooseneck and the rear axles, which is what gets the floor down to roughly 18 to 24 inches and leaves the most room under a 13'6" ceiling. A double drop is the same shape described from the side.

An RGN is a lowboy whose gooseneck comes off. Release it, the front of the well settles to the ground, and the machine drives straight in. A fixed-neck lowboy cannot do that — it loads by crane, or from the rear up over the tyres, which is a steeper climb onto a higher deck.

So the honest answer to "lowboy or RGN" is that you are not choosing between two heights. You are choosing between a crane and a ramp. If the piece drives, rolls or tracks under its own power, the detachable neck pays for itself the first time nobody has to book a lift.

RGN vs step deck: where the line actually falls

A step deck is not a lowboy. Its lower deck sits on top of the axles at 36 to 42 inches, so it is simpler, lighter and cheaper to run — and it is usually the right trailer right up until it is not.

Three things push a load off a step deck and onto an RGN: height above roughly 10 feet, weight past what the step deck's axles are rated for, and no crane or forklift at either end. Any one of them is enough, and none of them is a matter of preference.

• Under 8'6" tall, loads from the side — flatbed.
• Up to about 10 feet, crane or ramps available — step deck.
• Over 10 feet, very heavy, or it has to drive on — RGN or another lowboy.

An RGN does not make everything legal

It is the lowest practical starting point, not a permit waiver. A machine that is 12 feet tall on the ground is still oversize in the well of an RGN, and it still needs a permit, a route survey and possibly escorts. What the RGN buys is the difference between a routine permit and a route that has to dodge every overpass in the corridor.

Width and length work the same way. Once a load passes 8'6" wide it is permitted regardless of which deck it sits on, and the escort rules turn on the dimensions, not the trailer. That side of it is covered in oversize permits and pilot cars in Washington.

What to send when you ask for a rate

Four numbers and a photo settle the trailer choice in one exchange instead of three:

• Length, width and height of the piece as it will sit — not the crated dimensions from the catalogue.
• Weight, and where the centre of gravity is if it is not obvious.
• How it will be loaded and unloaded, and whether there is lifting equipment at either end.
• Pickup and delivery addresses, so the route can be checked for clearances before anything is promised.

We own the decks

Flatbeds, step decks and RGN lowboys are our own equipment, dispatched out of Kent and Tacoma alongside the container fleet. That is the reason an out-of-gauge box off the Port of Tacoma and the machinery it is going to sit next to can move on the same day under one dispatcher.

Questions we get asked

What is the difference between a lowboy and an RGN?

An RGN is a lowboy — the one whose gooseneck detaches. Drop the neck and the front of the well reaches the ground, so machinery drives on instead of being lifted. A fixed-neck lowboy sits just as low but has to be loaded by crane or from the rear.

What is a lowboy trailer?

A trailer with the deck dropped into a well between the gooseneck and the rear axles. The well sits roughly 18 to 24 inches off the ground, which leaves about 11'6" of legal cargo height against a 13'6" planning ceiling — the most of any open deck.

Is a double drop the same as a lowboy?

In practice yes. "Double drop" describes the shape: the deck drops once behind the neck and again ahead of the rear axles. Whether it is called a lowboy, a double drop or an RGN comes down mostly to whether the neck comes off.

RGN or step deck for a 10-foot machine?

That is right on the line. A step deck will usually take it, but only with a crane or ramps and the weight inside the axle rating. If the machine has to drive on, or the route is uneven and you are close to the height limit, take the RGN.

How tall can cargo be on a step deck?

Roughly 10 feet, working from a lower deck at 36 to 42 inches against a 13'6" planning ceiling. An RGN buys about another 18 inches.

When is an RGN worth the extra cost over a step deck?

When the piece is too tall for a step deck, too heavy for its axle rating, or when neither end of the move has lifting equipment and the machine has to drive on.

Do you provide the permits?

Yes. Permits, routing and escorts are arranged as part of the move, not left to the shipper.

Read next

• Oversize in Washington: what triggers a permit, and what triggers escorts
• Liftgate, residential and limited access: what the delivery site costs you

Long Road Transportation is an asset-based carrier operating its own trucks, chassis and heavy-haul equipment out of Kent and Tacoma, Washington. USDOT 3388302, MC 113242, SCAC LRDP.