One of the terms that I see discussed in the trucking literature is flatbed shipping. That’s when you have a simple trailer without any sides or top, just a … flat … bed. That’s used for any number of things that either don’t fit into a standard trailer or don’t need to fit into a standard trailer.
Small construction vehicles like bulldozers or back-hoes might be shipped via flat bed. You could put them inside a covered vehicle transport, but such rough-and-ready items don’t need dainty treatment, and it will be cheaper to use a flatbed, since they are less expensive to buy, maintain, and pull; remember that those sides have weight to them and will require extra gas to pull around.
Bulky items like concrete pipes or girders will fit into the flat bed category. They’ll often be bigger in one or more dimensions than your standard trailer and thus need a flat-bed ride and generally don’t mind being out in the elements for the duration of the trip.
If the cargo goes above certain dimensions, they will fit into the oversized or wide-load category and require extra handling and usually a wide-load labeled pick up riding behind the trailer; one of my MBA students from my teaching days worked driving one of those wide-load escort trucks and occasionally had to miss a class if a trip got him away from town on a class night.
Flatbeds are part of Momentum’s stock in trade as a freight company; they can handle just about anything you can think of moving.