ABSTRACT
Traditional construction planning tools, such as bar charts and network diagrams, do not represent and communicate the spatial and temporal, or 4D, aspects of construction schedules effectively. Consequently, they do not allow project managers
to create schedule alternatives rapidly to find the best way to build a particular design. Extending the traditional planning tools, visual 4D models combine 3D CAD models with construction activities to display the progression of construction over time. 4D models combine 3D CAD models with the project timeline (Cleveland, 1989). Systems linking 3D CAD models with schedule and other project information started to be developed in the mid-eighties (Kahan & Madrid, 1987; Atkins, 1988). Experience on many different types of projects (simple to complex, new to retrofit) has shown that combining scope and schedule information in one visual model is a powerful communication and collaboration tool for technical and non-technical stakeholders (Williams, 1996; Retik, 1997; Edwards & Bing, 1999).
