Challenges and Opportunities for Innovation in the Public Works ...

mechanical and structural design. This included footings and
foundations, structural steel, mechanical equipment, duct work,
pipe, and pipe components. Design drawings were made from the 3-D
geometry using the system's 2-D capabilities.
Using 3-D design, the design engineer translates the 3-D image in
his mind to create that same image on the screen of the workstation.
Structures and systems are continuous and complete. They
are not regulated or designed on separate sheets. Structural bays
are developed; general arrangements of equipment are fitted into
the bays; and pipe, HVAC, and electrical systems are routed between
equipment, avoiding interferences. When the model has been
completed, checked, and verified, drawings are then created. In
this fashion the design is represented in the model; drawings are
used to communicate that design. Most 3-D systems have been
developed to enable the geometry of the drawing to be created by
projecting the image of the model into a 2-D window where clipping
and dressing-up of the image can be conducted. Notes and
dimensions are then added.
A duct work configuration different from the original conceptual
design was developed in 3-D. The new design could have been
conducted in the 2-D mode; however, communicating that design with
the 3-D model among the project participants proved to be very
effective.
The Construction Industry Institute (CII) estimates that the cost
of rework on industrial projects exceeds 12 percent of the total
project cost. Design deviations, changes, errors, and omissions
account for 80 percent of the increased costs. Construction
deviations account for 20 percent. The CII cost influence curve
also shows that the earlier construction experience, methods, and
knowledge are introduced to a project's design, the higher the
probability that these factors will influence the design and reduce
cost and schedule. With this philosophy in mind, two full time
construction supervisors were assigned to implement
constructibility issues early in the design of the project.
Construction worked closely with the engineers and designers during
the design process. Areas of concern included labor and material
access, scheduling, and construction equipment placement.
During the design process, Construction Specialists are reviewing
the models for constructibility. In the past these specialists
reviewed completed drawings which did not allow a great deal of
flexibility to make changes. Now copies of the model are used
starting in the conceptual stages of the project continuing through
detailed design to assess site layout, craft and equipment access,
and ease of construction; implement modularization; size pipe
spools and locate field welds; plan the construction process;
select and size construction equipment; and create the construction
schedule. The 3-D design model provides the project with a
powerful communication tool utilized among all levels of the
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