Many construction practitioners and researchers have developed four-dimensional (4D) models by linking the three-dimensional (3D) components of a building information model (BIM) with the network activities of a project schedule. In such a 4D model, the BIM provides limited information, except for the 3D components. To enhance the benefits of using BIM in 4D applications, this study proposes an interface system that uses the BIMs ability with regard to quantity takeoffs of required materials (such as steel, forms, and concrete) to support site-level operations simulation, ultimately leading to the generation of a project schedule. Our proposed system includes mechanisms that collect, store, and transfer information among various software packages. Facilitated by the BIM's quantity takeoffs, the operations simulation is able to consider uncertain durations of work tasks, which allows it to consider the competing needs for resources among multiple work tasks, and to evaluate various resource allocation strategies in order to create a suitable construction plan. Finally, the resulting project schedule is also linked to the BIM 3D components, thus producing an improved BIM-based 4D model.