A Self Propelled Modular Transporter (SPMT) is a platform vehicle with a large array of wheels on the bottom. They are used for transporting massive objects such as bridges, oil refining equipment, huge motors, large bridge sections, and other objects that are too big or heavy for truck

Truck

A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

s but trucks can provide traction and braking for the SPMTs on inclines and descents. These vehicle may also be called a Self Propelled Modular Trailer.

SPMTs are used in many industry sectors worldwide like for construction

Construction

In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

 and oil

Oil

An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....

 industries, in the shipyard and offshore industry, for road transportation, on plant construction sites and even for moving huge Oil platforms and have been recently begun to be used to replace bridge spans, in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and more recently, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

.

A typical SPMT can have a grid of several dozen computer-controlled wheels, all individually controllable and steerable, in order to evenly distribute weight and steer accurately. Each individual wheel can swivel independently from other wheels, to allow the SPMT to turn, move sideways, or even spin in place. Some SPMTs allow each wheel to telescope independently of each other, so that the load can be kept flat and evenly distributed while moving over uneven terrain. As SPMTs often carry the world's heaviest loads on wheeled vehicles, they are very slow vehicles, often moving at under one mile per hour while fully loaded. Some SPMTs are controlled by a worker with a hand held control panel, while other SPMTs have a driver cabin. In addition, multiple SPMTs can be combined to transport massive building-sized objects.