Several samples of residual base course material were studied to investigate the effects of compaction on their physical and mechanical properties. Test results of compaction and CBR obtained for borrow pit material are compared with repeatedly used soil samples from the road. From analysis of changes of strength of materials before, during and after construction, and also site observations, it is recommended to establish not only the minimum requirements for compaction density, but also the maximum density. Some guidelines are discussed for control of the level of compaction at the site.