The self-propelled modular transporters are called SPMT-trailers. They are custom-built for one or more specific transportation assignments. It can be anything from moving ships to towing a bridge section and internal transportation of heavy nacelles that weigh several tons for the wind mill industry.
SPMT-trailers are very flexible. The number of modular axles is customised for the specific assignment, and the axles can turn 180 degrees. A powerful Power Pack ensures the traction, and the trailer is controlled by a walking operator with a handheld remote control with a joystick. This gives a full overview of the handling process.