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What is a flat deck truck or trailer?

The flat deck refers to the area of the truck or trailer that the goods are loaded onto – it’s a large uniformly flat area which items can be placed on and secured.

Trailers can be heavy or light, and can be semitrailers or full trailers.

Flat deck heavy trailer carrying concrete blocks
Simple light trailer that’s sometimes called a flat deck, but it’s often called a machinery trailer. It doesn’t have fold-down sides (the wheels would be in the way), but this allows for the trailer deck to be lower for a lower centre of gravity with the load

There are even b-train flat deck combinations.

9-axle b-train flat deck carrying tractors

Flat deck trailers and trucks do not have curtains or a hard-side body – they are uncovered – however, they might have stanchions or fold-down gates.

Two stanchions on a flat deck truck

If the trailer has a step in it, it’s called a step-deck trailer, drop-deck trailer, lowboy or transporter trailer.

The step deck or allows for the main loading area to be lower, while the front part of the deck accommodates the fifth wheel.

How are loads secured to a flat deck truck?

Drivers must know how to secure loads to a truck or trailer before using a flat deck truck or trailer because there are no rated curtains or hard sides to contain loads.

Flat deck trailers have anchor points so that loads can be tied down. These can be rope rails, chain hooks or ISO container locks.

Rope rail with a hook and keeper from a ratchet strap
Chain hook on a flat deck trailer
ISO container locks on a flat deck trailer so that containers can be transported

The decks can be metal or metal and wood. Wooden decks have more friction than metal decks, but wear more quickly.

A wooden deck on a flat deck truck showing dunnage strapped with chains, towing a flat deck trailer with a headboard

At the front of the flat deck on a truck is a headboard. Some trailers have headboards, too (as shown in the above photo), and the load should be against the headboard.

The headboard has protected the cab when this load moved on this flat deck truck – the driver didn’t load it properly
The headboard isn’t designed to take that much weight – the load still must be strapped down.

If the trailer is a light trailer, the driver must still know how to secure loads to a light trailer.

Drivers can be fined for transporting an unsecured load.

What are flat deck trucks and trailers used for?

The flat deck is used for transporting items which are not able to be transported in curtainside or hardside trailers for various reasons:

  • Hardside trailers can only be loaded from the rear
  • Curtainside trailers have curtain poles and a rear door or panel which obstructs access
  • Curtainside and hardside trailers are more expensive
  • Flat deck trailers can be loaded from the top
  • Flat deck trailers can be loaded oversize (with the right permits)
  • Flat deck trailers can be loaded and unloaded with a truck loader crane
  • A container can be secured to a flat deck trailer if a skeletal trailer isn’t available
  • Flat deck trucks with side gates are easy to load with aggregates and soil

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Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers' Guild

Posted in Advice
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