Final answer:
Highway crews use steamrollers to smooth a road by compacting the asphalt and making the road surface smooth.
Step-by-step explanation:
A highway crew uses steamrollers to smooth a road. Steamrollers are heavy construction vehicles equipped with heavy drums or rollers that are used to compact asphalt or other materials and make the road surface smooth. The weight of the steamroller and the pressure exerted by the roller help to level the road and remove any irregularities.