Several travelling and compaction tests were executed by use of a two-axle, two-wheel road roller during driving and braking action on an air-dried weak decomposed granite soil. The experimental data were compared with the simulation analytical results. It is clarified that the amounts of sinkage, the driving and braking forces, and the effective driving and braking forces of the front and rear roller increase with the increment of the absolute value of the slip ratio or skid, and the optimum traffic condition of the road roller to obtain the maximum compaction density of the terrain is that both the front and rear roller are operating at -5% skid during braking action.