BIM-Based 4D Modeling and Scheduling - Construction Project Scheduling and Control - page 397

as object information. The incorporation of object information into 3D models adds
“smart” characteristics to the building components, which provide information about
materials, interconnectivity, the budget code attached to the object, material suppliers,
responsible subcontractors, and so on. The physical environment of projects attached
with the building characteristics enables project parties to have a better understanding
of the architectural, structural, mechanical, and electrical design of the project. Thus,
compared with the traditional designs and 2D plans, 3D intelligent models allow the
identification of potential conflicts and/or errors, and inconsistencies among different
design documents and drawings, and they detect probable project clashes (e.g., HVAC
and fire protection clashes). In addition to the visual representation of the project
design, 3D models are helpful in processing project data, automating design changes,
ensuring collaboration of the project participants, and easy sharing of knowledge and
information.
Definition and Benefits of 4D Modeling
4D modeling is a visualization method that incorporates 3D building model into
the project timeline, including the project schedule, resources, quantities, and project
phasing. In general, 4D models are defined as 3D models with the addition of time
associations. 4Dmodels allow visualization of a sequence of activities in terms of build-
ing components and “duration to complete” information that are associated with each
component. Thus, they can be regarded as a virtual simulation of the construction pro-
cess from its beginning to its end, with location, resources, and progress information.
4D models enable project participants to visualize and evaluate how the project will
be executed over a predefined project duration. One of the major contributions of
the 4D models to the scheduling technology is that they automatically capture the
variations between the actual and the planned schedule by simulating its virtual model
in case actual site data are captured (i.e., with time-lapsed photographs). Thus, more
dependable and reliable assessments can be carried out because of the visual informa-
tion about which activities are planned to be finished and which activities have actually
finished. This can be an invaluable tool in some delay claim cases. The simulation of
construction progress, in turn, provides the evaluation of project performance in terms
of time and cost.
4D models are widely utilized by contractors, engineers, designers, owners, sub-
contractors, and suppliers along planning-operation phases of construction projects.
When the 4D models are generated and used within the construction value chain and
the early involvement of all project participants is ensured, some bottlenecks (such
as constructability problems, resource allocation, tower-crane location and selection,
etc.) that can delay the success of projects can be avoided. Probable communication
and coordination problems that arise due to the highly fragmented nature of the indus-
try can be minimized by sharing project information within a virtual platform, as well
as serving as transparency between owners and parties. With the use of 4D models,
project information, including architectural, structural, and MEP designs, and site
management plans, can be effectively retrieved and shared by diverse participants in