Earthworks planning for road construction projects is a complex operation and the planning rules used are usually intuitive and not well defined. An approach to automate the earthworks planning process is described and the basic techniques that are used are outlined. A computer-based system has been developed, initially to help planners use existing techniques more efficiently. With their input, the system has been extended to incorporate a knowledge base and a simulation of the earthworks processes. As well as creating activity sets in a much shorter time, the system has shown that for a real project, the model is able to generate activity sets that are comparable to those generated by a project planner.