Improving earthmoving estimating by more realistic knowledge

Abstract

Earthmoving operations are often a very important aspect of a civil engineering project. Very accurate knowledge of the earthmoving operation is often the vital, critical element in the formation of a good and accurate cost estimate and schedule because of its prominent role in influencing costs and time. Inaccuracies are often built into earthmoving estimates by the fairly sweeping assumptions that are made during the estimating process. These problems were revealed in answers to a questionnaire and in interviews with experts. The factors that affect the performance of machines are discussed, including the common types of earthmoving operations. The importance of haul distance in determining which type of equipment should be used is also considered. The selection of equipment and estimation of costs for earthmoving depend heavily on human experience. The means of eliciting human experience are described in detail. Because of this reliance on human experience, a prototype knowledge-based expert system was developed using a shell program. The system is able to select the most appropriate fleet of machines, and estimate the cost, for use as a decision support system in planning an earthmoving operation. Key words: construction, earthmoving, estimating, knowledge, expert system, realistic knowledge.