This paper presents a methodology that integrates fuzzy clustering and computer simulation and demonstrates its use in modeling earthmoving operations. A simulation system (SimEarth) was developed to model earthmoving operations utilizing object-oriented features and discrete event simulation. Fuzzy clustering is used to provide realistic estimates of haulers' travel time so as to improve the accuracy of the simulation results. A case study involving the construction of a dam is presented to illustrate the capabilities the proposed simulation engine and the developed fuzzy clustering methodology for estimating haulers' travel time.