Road roller

As internal combustion engines improved during the 20th century, kerosene-, gasoline- (petrol), and diesel-powered rollers gradually replaced their steam-powered counterparts.

They used similar mechanisms to transmit power from the engine to the wheels, typically large, exposed spur gears.

Road rollers use the weight of the vehicle to compress the surface being rolled (static) or use mechanical advantage (vibrating).

On large freeways, a four-wheel compactor with padfoot drum and a blade, such as a Caterpillar 815/825 series machine, would be used due to its high weight, speed, and the powerful pushing force to spread bulk material.

These rollers feature two rows (front and back) of pneumatic tyres that overlap, and the flexibility of the tyres provides a kneading action that seals the surface and with some vertical movement of the wheels, enables the roller to operate effectively on uneven ground.

Once the soil base is flat the pad drum compactor is no longer used on the road surface.

[citation needed] The next course (road base) is compacted using a smooth single drum, smooth tandem roller, or pneumatic tyre roller in combination with a grader and a water truck to achieve the desired flat surface with the correct moisture content for optimum compaction.