Step deck and RGN trucking for tall and heavy pieces

Which trailer, and why

A standard flatbed's deck sits about five feet above the road, so a load taller than about eight and a half feet puts the combination over the fourteen foot height limit. A step deck, also called a drop deck, has a short upper deck over the tractor and a long lower deck about three and a half feet off the ground, which gives about ten feet of load height. A double drop lowers the middle of the trailer further, to about two feet, for pieces up to roughly twelve feet tall, but the well is short. An RGN, a removable gooseneck lowboy, detaches at the front so equipment can be driven or winched onto the well from the ground, carries tall and heavy pieces at the lowest deck height, and can be built with extra axles for the heaviest loads.

The choice is made from the piece: its height sets the deck, its weight sets the axle count, and its length sets whether the well is long enough. We match the trailer to the drawing, not the other way around.

Loading an RGN

An RGN is loaded with the gooseneck off. Tracked and wheeled machines drive on under their own power; skidded equipment is winched up or set by crane into the well. The well is the lowest point, so the heaviest part of the load goes there, over the trailer's main axles, and the load is chained at its designated points with the number and grade of chains the weight requires. Then the neck goes back on, the deck heights are checked, and the overall height is measured with a pole before the truck leaves the yard, because the permit is written for a specific height and a load that measures taller than the permit says cannot legally move.

Step decks load by crane or forklift from the side or from a dock onto the upper deck, and ramps let small machines drive onto the lower deck. Tarps on a step deck are a specific skill: the drop in the deck means the tarp has to be cut and secured around the step, and a tarp that is not done right flaps itself to pieces on the first windy desert stretch.

Permits, weight and the western roads

A tall piece on a step deck or an RGN is usually within the height limit but over width, and a heavy piece is over weight, so most of these moves carry permits. Weight is spread across axles to satisfy each state's bridge formula, and the heaviest pieces move on trailers with three, four or more axles, or with a jeep dolly and a stinger that add axles at both ends. Overweight permits name the route, and some bridges on the direct route may be excluded, which can add miles.

The western passes matter more to a lowboy than to a van. The Cajon Pass and Mountain Pass on Interstate 15, the Tejon Pass of Interstate 5, the Interstate 8 grade into San Diego County and the long desert stretches of Interstate 10 are hard on a heavy combination's brakes and cooling, and chain season on the Siskiyous and Donner Pass can stop an oversize load for a day. We plan for the road as well as the permit.

Where this equipment is and what it costs in notice

Step decks are common in every western market, and a step deck load on one of our regular lanes can often move on the same notice as a flatbed. RGNs and multi axle lowboys are fewer, concentrated around the heavy industry and construction work in Phoenix, the Inland Empire, the Central Valley, the Bay Area, Portland and the Puget Sound, and they are booked ahead. A week of notice for an RGN move is normal, more for the heaviest pieces, and we say so when we quote rather than offer a trailer that is not there.

Every carrier that hauls one of these loads for us is vetted through Highway for identity, authority and insurance ahead of dispatch, and we confirm the carrier's securement gear and oversize equipment match the piece.

What we need to quote

• Length, width, height and weight of the piece, from the manufacturer's shipping drawing
• How it loads: drives on, is winched, or is lifted by crane, and where its lifting and tie down points are
• Whether it must be tarped or can travel open
• Pickup and delivery sites, with their crane or ramp arrangements and hours
• The delivery date the site needs, so the trailer and the permits can be arranged in time