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

calculated in the database by multiplying material quantities by
historical craft installation labor rates and craft hourly wage
rates.
Stone & Webster uses COMANDS in two modes: on Stone & Webster
designed projects and projects designed by other engineering
companies.
In the first mode, projects are designed and engineered in CATIA 3-
D graphics. The project database is developed simultaneously.
Drawings are generated by projecting a solid geometry image into a
2-D window. Notes and dimensions are then added. Construction
personnel then use this information to develop the COMANDS
database.
In the second mode, the project is designed by others. Threedimensional
models and the database are then developed from the
design drawings. The drawings are loaded into CATIA by
construction, estimating, and scheduling engineers. Experience has
shown that information can be modeled from 2-D drawings very
rapidly. The boiler building of a 150 MW pulverized coal power
plant was modeled in three weeks by two engineers. The model
included the structural steel columns and beams, the boiler, all
major equipment, piping, HVAC duct, cable tray, and platforms. The
modeling effort simulates construction in the field and
familiarizes the participants with the project's scope of work.
Since all components have to fit together in the 3-D model, the
design is verified prior to start of actual construction
activities, with constructibility analysis, value engineering, and
interference identification being conducted concurrently.
Since COMANDS is used as a construction tool, the level of detail
that is required in the 3-D model need only be at the level that
project management chooses to monitor the construction activities.
Modeling to the nuts and bolts level would be extremely time
consuming, whereas a building block model would not provide
sufficient detail to be useful. Stone & Webster models to the
level of detail that is identified in the project's work breakdown
structure (WBS). The WBS account/activity list identifies this
level of detail. An activity can be tracked at a system level; for
example, "Install Feedwater Piping and Testing." It can also be
tracked at a component level where each account is identified in
the installation process; for example, 10 inch carbon steel pipe,
pipe supports, welding, valves, painting, insulation, testing, and
turnover. As a rule all civil and structural activities are
modeled to the level of detail in the design. This includes
excavation, backfill, foundations, slabs, walls, and structural
steel. Mechanical equipment has been modeled as it physically
exists and as volumetric blockouts. Pipe has been modeled with and
without valves and fittings. Electrical equipment is modeled as
equipment blockouts, and cable tray is routed dimensionally
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