Construction schedule logic development: The impact of visualization

The advantages of 3D CAD walk-through models over 2D and 3D hard copy drawings in planning construction schedules were tested. A section of an existing co-generator power plant was used for the case study. 50 participants both "experienced" (largely AEC industry professionals) and "inexperienced" (largely graduate students in the University of Colorado's Construction Engineering and Management Program) were asked to extract construction activities involving physical elements from one of the three project representations. Each test subject, using the one design medium assigned to him as his reference, then was instructed to develop a sequence of activities from a complete list provided to him. Physical constraints were the only ones the participants had to consider. The resulting schedules were compared. Those developed using the 3D electronic model had on average, (1) fewer missing activities, (2) fewer missing relationships, and (3) fewer invalid relationships. Also, they had on average (1) shorter durations, (2) fewer critical activities, and (3) smoother resource fluctuations. Both experienced and inexperienced planners benefited from the walk-through model, but the inexperienced benefited more, especially in developing valid activity relationships. Another 20 participants were presented with a 3D CAD animated schedule and asked to identify safety and overcrowding concerns. There was consistency among the majority in the elements they identified. Although the available literature suggested major barriers to implementation of this technology in construction would be resistance to change in the industry, cost, and extensive training requirements, these were not apparent in this research: the main problem was the lack of technical support for such an animation application.