A compactor includes a frame supporting a first roller assembly and a second roller assembly. At least one of the first roller assembly and the second roller assembly is moveable relative to the frame in a motion that includes an upward vertical component and a downward vertical component. An actuator is coupled to at least one of the first and second roller assemblies and is operable to repeatedly move at least one of the roller assemblies relative to the frame in both the upward vertical component and the downward vertical component to oscillate the roller assemblies relative to each other.