A steam roller is a heavy construction vehicle used to flatten surfaces. Synonyms for steam roller include compactor, road roller, asphalt roller, tar roller, and earth roller. These synonyms reflect the different types of surfaces steam rollers can be used on, such as roads, asphalt, tar, and earth. Compactors are machines that compress material to reduce its volume and increase its density. A road roller is a type of compactor used to compact soil, gravel, asphalt, or concrete in road construction. Asphalt rollers and tar rollers are specifically designed to compact asphalt and tar, respectively. Earth rollers are used in construction to compact soil or backfill.