Formalizing the Four-Dimensional (4D) Topology As the Base for 4D Analysis in Construction Planning

Construction site is a dynamic environment in which workspaces of construction activities continuously change in aspects of space and time throughout the entire lifecycle of a project. Without a comprehensive plan that considers spatial-temporal relationships between the site objects, conflicts or improper layout may frequently occur on construction site and influence the success of the project. Four dimensional (3D+time) modeling technique has been proven to be useful and promising in construction planning. However, it still lacks the ability to capture the site dynamic natures and analyze spatial-temporal relationships. The overall goal of this study is to develop a 4D topology system based on GIS concept for construction planning, which enables deriving 4D relationships between site objects in real-time and provides a comprehensive 4D topological analysis function, overcoming a major drawback in the current 4D practice. This paper presents the result of the development of the 4D topology framework in construction. The semantics of 4D topology are defined to describe corresponding dynamic construction site events. A 4D topological framework is formalized to capture the site dynamics which forms the base for 4D analysis. It could complement the CPM or 3D model in construction planning under both spatial and temporal constraints. The direction of future research in 4D topology-based analysis is also discussed.