A road roller(sometimes called a roller-compactor, or just roller) is acompactor typeengineering vehicle used tocompact soil,gravel, concrete, or asphalt in theconstruction ofroads andfoundations.
In some parts of the world, road rollers are still known colloquially as steam rollers, regardless of their method of propulsion. This typically only applies to the largest examples (used for road-making).
Road rollers use the weight of the vehicle to compress the surface being rolled. Initial compaction of the substrate is done using a pneumatic-tyred roller, with two rows (front and back) of pneumatic tyres. The flexibility of the tyres, with a certain amount of vertical movement of the wheels, enables the roller to operate effectively on uneven ground. The finish is done using metal-drum rollers to ensure a smooth, even result.
Rollers are also used in landfill compaction. Such compactors typically have knobbed ('sheeps-foot') wheels, and do not achieve a smooth surface. The knobs aid in compression due to the smaller area contacting the ground.
