Model-Centric Design
Danny L. Kahler, P.E.
Session T31
4:00 p.m. – 5:00 p.m.
August 29th, 2006
ASQ Annual Conference
Energy & Environmental Division
Design & Construction Division
Tucson, Arizona
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Speaker Introduction
Danny L. Kahler, P.E.
 Civil Engineer
 Bridgefarmer & Associates, Dallas, TX
 20+ years of engineering experience
 ASQ Senior Member
 ASQ CQA, CQM, CQE and CSQE

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Vocabulary

Model - A simplified representation of a
system at some particular point in time or
space intended to promote understanding of
the real system

System – A system exists and operates in
time and space
(Definitions
obtained from Society for Modeling and Simulation International)
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Vocabulary (Continued)

Model Centric Design – All significant
design processes extract information from
and update changes to a digital model that
represents the real system
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Traditional Design Technology

The “model” is represented by lines and
numbers on rectangular sheets
– Each sheet only shows small section of the
design
– Visualizing the proposed design requires
significant practical experience
– Changes to the design are difficult
– Large labor forces are required for drafting
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Enabling Technology

Computer software that allows a design to
be drawn using real world units in the same
coordinate system that will be used for
construction

Computer networks that allow multiple users
to to see the latest version of any design
component in it’s actual location
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IT’S NOT ABOUT SOFTWARE!

Software packages are just tools that help
us work with the data

We use software to retrieve the data,
analyze it, manipulate it, put it back in, and
present it

Model-centric design is about improving the
way we use the data to make design
decisions
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Software Won’t Improve Anything

Design firms continue to invest in the latest
software with little improvement in real
productivity

Managers eventually turn deaf ears to
production staff requests for each new
“killer” application

Senior designers still rely on plan sheets to
make design changes
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We Need Model-Centric Thinking

Firms can separate pure design from
construction document drafting

Managers can make choices about
hardware and software investments based
on actual productivity needs

Senior designers can base their decisions
on the actual design, not limited sheet views
of it
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Evolution of Model-Thinking

Plans Only

“What’s a model?”

Plans Visualization

The plans build the
model
Plans and model
coexist
The model builds the
plans
– Plans

Roundtrip Engineering
– Plans

Model Only

Model
Model-Centric
– Plans

Model

Model

Pure design (no more
plan sheets)
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Do We Still Need Plans?

Agencies will continue to require traditional
plans for many years to come

With the Model-Centric approach, the sheets
just become views of the model

Each printing of the sheets reflects the most
current version of the design model
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Why Change the Current System?
Design Among Multiple Agencies
 Tighter Project Schedules
 Design/Build Project Teams
 Increased Cost of Errors
 Increased Cost of Disputes
 Increased Cost of Personnel
 Fewer “Seasoned” Engineers

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What Motivates Us to Change?






Better use of technical staff
Less impact from design changes
Improved visualization of the project
Improved communication with clients and
contractors
New methods of discovering and eliminating
design & construction conflicts
New design practices to match improvements
in construction & survey technology
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What are the Benefits?









Allows shorter design schedules
More production with less staff
Designers doing design not drafting
Portability of design to other platforms
Clients have more influence during design
Faster response to client changes
Reduced potential for errors
Reduces drudgery of plans production
Better communication with construction
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What do Design Firms Need?

People trained to communicate in the
“language” of design models and real-time
design changes

Development of guidelines to help predict
revised production rates and labor costs

Establishment of new skills in how to control
and assure the quality of the model

We need Model-Centric Quality Assurance
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Model-Centric Quality Assurance

Model-Centric Quality Assurance
occurs when the evaluation of
adequacy of a design is based on the
integrated review of the actual design
model rather than a fragmented
inspection of individual views (plans)
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Traditional Design QA

Document Based

Multiple Iterations of Construction Plans

Heavy Focus on Appearance

Frustrating Amount of “Drafting” Comments

Reviewer Reward based on Volume of
Comments Generated
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Implementing Model-Centric QA

Requires standards for model definition
- these standards may already be
hidden in agency CADD standards

Needs standardized or compatible
software that faithfully represents the
proposed design model to the reviewer
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Example of Model-Centric QA
Problems with storm sewer profiles found
early in the design process
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Model-Centric QA can be more
than review

If the reviewer and designer are on the same
software platform, an experienced reviewer
can often provide feedback of what process
error or errors probably caused the design
flaw

QA can evolve from basic third-party product
inspection to a team member that provides a
value-added analysis of needed design
process improvements
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Taxonomy of Model-Centric QA

Fit
– The static 3-D Integration of the Project

Flow
– Things the project must transport: storm
drainage, sewage, vehicles, etc.

Function
– Ability of subsystems to do their jobs: signals,
gates, message boards, roadway signs, etc.
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Can we improve Model-Centric QA?

By borrowing Software Quality Concepts:
– Validation
– Verification
– Accreditation
*Terms obtained from DOD sources
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VALIDATION

Validation: The process of determining the
degree to which a model is an accurate
representation of the real-world from the
perspective of the intended use of the model

Does the model show us how the
components of a proposed design will
actually fit together?
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VERIFICATON

Verification: The process of determining that
a model implementation accurately
represents the developer’s conceptual
description and specifications

Does the model represent a design that will
meet the performance requirements if
constructed?
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ACCREDITATION

Accreditation: This is the official certification
that a model is acceptable for use within the
context of a specific objective

Is the model sufficiently detailed to produce
accurate construction documents ready for
bid?
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Can Contractors Take Advantage
of a Design Model?

Some contractors already request
source design files, and often report
the files have fewer errors than the
signed and sealed paper plan sheets

Agencies can establish design contract
requirements for designer-validated
models adequate for bidding purposes
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Model-Centric Construction

Machine control from the model

Inspection without stakeout

Real-time status of construction
progress

True “As-Built”
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How can Model-Centric thinking
reduce project costs?

Fewer review documents

Faster turnaround

More efficient use of manhours

Decreased communication errors

Decreased project risk

Early resolution of disputes
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Future of Model-Centric Design




Contractors will begin to expect reliable
models from owner agencies in order to
prepare more competitive bids
Owners will respond to contractor demands
by expecting designers to deliver validated
design models
Stress of system change may force some
people out of design and encourage others
to progress faster
Clients will have the option to conduct realtime reviews of the design model instead of
waiting for a submittal
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Where to Get More Information
Danny Kahler, P.E., Texas
 ASQ Design and Construction Division
 Software Vendor, i.e Bentley,
Autodesk, Trimble, etc
 LandXML Committee
 State Departments of Transportation

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Questions?
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Thank you for your attendance
Now we can all go hit happy hour
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