Understanding Pre-Construction Simulation Activities to Adapt Visualization in 4D CAD Collaborative Tools

Increasing productivity and efficiency is an important issue in the AEC field. This area is mainly characterized by fragmentation, heterogeneous teams with low lifetimes and many uncertainties. 4D CAD is one of the greatest innovations in recent years. It consists in linking a 3D model of the building with the works planning in order to simulate the construction evolution over time. 4D CAD can fill several needs from design to project management through constructivity analysis and tasks planning (Tommelein 2003). The literature shows that several applications have been proposed to improve the 4D CAD use (Chau et al. 2004, Lu et al. 2007, Seok & al. 2009). In addition, studies have shown the real impact of 4D CAD use in construction projects (Staub-French & Khanzode 2007, Dawood & Sika 2007). More recently, Mahalingam et al. (2010) showed that the collaborative use of 4D CAD is particularly useful during the pre-construction phase for comparing the constructability of working methods, for visually identifying conflicts and clashes (overlaps), and as visual tool for practitioners to discuss and to plan project progress. So the advantage of the 4D CAD collaborative use is demonstrated. Moreover, several studies have been conducted both in the scientific community and in the industrial world to improve it (Zhou et al. 2009, Kang et al. 2007). But an important need that remains in collaborative 4D CAD use in construction projects is about the adaptation of visualization to the users business needs. Indeed, construction projects have very specific characteristics (fragmentation, variable team, different roles from one project to another). Moreover, in the AEC field several visualization techniques can represent the same concept and actors choose one or another of these techniques according to their specific needs related to the task they have to perform. For example, the tasks planning may be represented by a Gantt chart or by a PERT network and the building elements can be depicted with a 3D model or a 2D plan. The classical view (3D + Gantt) proposed to all practitioners in the available 4D tools seems therefore not suiting the needs of all. So, our research is based on the hypothesis that adapting the visualization to individual business needs could significantly improve the collaboration. This work relies on previous ones and aim to develop a method 1) to choose the best suited views for performed tasks and 2) to compose adapted multiple views for each actor, that we call business views. We propose a 4 steps-method to compose business views. The first step identifies the users business needs, defining the individual practices performed by each actor, identifying his business tasks and his information needs. The second step identifies the visualization needs related to the identified business needs. For this purpose, the user's interactions and visualization tasks are described. This enables choosing the most appropriate visualization techniques for each need (step 3). At this step, it is important to describe the visualization techniques and to be able to compare them. Therefore, we proposed a business view metamodel. The final step (step 4) selects the adapted views, defines the coordination mechanisms and the interaction principles in order to compose coordinated visualizations. A final step consists in a validation work to ensure that the composed views really match to the described business needs. This paper presents the latest version of the method and especially presents our latest works about its first and second steps. These include making more generic the business tasks description in order to be applicable within most of construction projects and enabling to make correspondence with visualization tasks