Ruston Proctor steamroller (road roller)
Steamroller by Aveling and Porter from early 20th century. On display at the Gangaramaya Temple in Colombo.
Front view of Aveling and Porter steamroller at the Gangaramaya Temple in Colombo.

A steamroller (or steam roller) is a form of road roller – a type of heavy construction machinery used for leveling surfaces, such as roads or airfields – that is powered by a steam engine. The levelling/flattening action is achieved through a combination of the size and weight of the vehicle and the rolls: the smooth wheels and the large cylinder or drum fitted in place of treaded road wheels.

The majority of steam rollers are outwardly similar to traction engines as many traction engine manufacturers later produced rollers based on their existing designs, and the patents owned by certain roller manufacturers tended to influence the general arrangements used by others. The key difference between the two vehicles is that on a roller the main roll replaces the front wheels and axle that would be fitted to a traction engine, and the driving wheels are smooth tyred.

The word steamroller is frequently used to refer to road rollers in general, regardless of the method of propulsion.[1]