This paper presents the development and testing of the Virtual Construction Simulator (VCS), a 4D CAD generation prototype which allows a user to develop a construction schedule by interacting directly with the 3D building model. The prototype application was developed in a 3D game engine interface. The VCS is developed to allow a user to group 3D components into construction assemblies, sequence the assemblies, and review the 4D model for the project. The VCS interface was assessed through a classroom exercise where 10 student groups developed construction schedules for a portion of a project. 5 of the student groups used the VCS application and 5 groups used a traditional 4D CAD modeling application for reviewing a schedule generated in a CPM application. The VCS allowed the groups to be more focused on the 3D model during the schedule process and aided in the identification of more innovative ideas.