The objective of this paper is to identify and study the feedback mechanisms required for the operational simulation of construction projects. To illustrate the concepts involved, we choose a demonstration in earth-moving operations. Emphasis is placed on treating the simulation system as an integrated unit, where site changes through simulation affect the performance parameters governing the simulation model. The behavior of the model through simulation is displayed with the aid of computer graphics. Animation is used to portray a dynamic representation of the construction site and resources through time. The main advantage achieved through the use of animation is the increased communication between members of the construction team in addition to the early detection of potential problem areas. In the simulation model, graphic elements used for model representation (e.g., trucks and loaders) resemble those actually used, thereby creating a realistic interaction medium that portrays the different operations involved.