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Managing the Model: “We Can Do It Faster the Old Way”

Mark Scacco on April 1, 2015 - in Column, Modeling

I’ve been hearing the title of this column, in one form or another, from engineering and architectural design firms for more than 20 years. I hear it from drafters, designers, engineers, architects, principals and owners, and it’s usually in response to why they’re not using modeling software they often already own.

I heard it when the industry was moving from hand drafting to CAD drafting. I heard it when CAD drafting was first beginning to be supplanted by attached object data, and basic modeling tools began. I hear it again as rudimentary modeling gives way to true 3-D/4-D/5-D modeling. And I hear it as detailed modeling transitions to BIM/VDC.

The reality is that this comment is usually true! There’s also a fundamental lack of understanding of what modeling is and its intrinsic value to organizations.

Hammer It Out

In my previous “Managing the Model” column, I stated that “models are not an end in themselves—they are tools.” Like all good tools, models should make a task easier and contribute to a project’s overall efficiency. And by nearly all accounts, models do this exceedingly well.

So why do so many feel they “can do it faster the old way?” Why can so many organizations complete various design and drafting tasks faster with their old tools? Let’s examine this question using an analogy: the hammer.

A hammer is a simple, yet effective, tool for pounding nails. It’s been around for a long time, and practically everyone knows how to use it with little to no training. It’s inexpensive and reliable. It’s also hardly ever used by professionals.

For driving nails, the hammer has been replaced by a much more complicated tool that’s orders of magnitude more expensive, requires the purchase of additional hardware, and isn’t intuitive to setup and use. This replacement tool is the nail gun, which requires an air compressor and hose (or battery for electric models), nail cartridges and periodic maintenance. Users need to be trained on how to set it up and use it before they can start driving nails.

And yet, because of its vastly superior performance, it has made the hand-held hammer almost extinct. It can drive a series a nails with a precision and speed that a hand-held hammer could never touch, ultimately producing a better finished product in a shorter amount of time. Owners and managers of construction companies understand the upfront costs and efforts associated with adopting nail guns as well as the benefits. And because of such understanding, the decision to switch is easy.

For engineers and architects, 2-D CAD and basic modeling are the hammer, and true 3-D/4-D models are the infrastructure industry’s nail gun. At first, creating real, functional models of surfaces, roads and bridges, utilities and more is indeed a more laborious task than drawing simple lines and curves and perhaps attaching object data. If the end goal is only to draw lines and curves, then a model is overkill; indeed, your team could and should be able to do it faster the old way.

However, simple linework lacks utility beyond a 2-D drawing of the feature it represents. Infrastructure projects are a series of interrelated components; a change to one component can have a ripple effect on one or more additional components. The true power and time-saving efficiency of a model becomes apparent in developing and drafting this initial design and then again later when revising.

Value in Initial Design

Existing ground and utility conditions provide initial design constraints, such as roadway connection points and utility invert elevations. In turn, roadway centerline elevations drive the elevations of the roadway surface and curbs and gutters. Gutter and surface elevations dictate manhole and inlet locations, rim elevations and sewer depths. Drainage area and outlet elevations are directly related to runoff treatment, storage and discharge, and so on. Modeling a project allows developers to easily and efficiently consider many alternatives to help arrive at the best design and not one that’s simply good enough.

When creating construction documents to convey design intent, developers are required to accurately provide a fair amount of technical information. By creating models, as opposed to drawings, much of this information can be added with just a mouse click. The tedious, error-prone tasks of calculating, drawing and labeling spot elevations, pipe slopes, cross-sections, material quantities, contours and more become a true byproduct of model creation.

Value in Revisions

In an effective, dynamically interactive 3-D model, dependent elements of the design and drafting automatically adjust as needed when changes are made. For example, any changes to roadway alignment geometry will automatically propagate to station labels, roadway profile geometry and labels, and roadway cross-sections.

This same benefit extends to subsequent revisions of the initial design. Every design is subject to review, which often results in needed revisions that can take a long time and consume a large portion of the design budget. A dynamic model makes short work of these tasks. I have seldom, if ever, heard someone say they can make revisions more quickly “the old way.”

A true comparison of the old way vs. modeling is to total the time and effort required to perform all the tasks, from initial design concepts to surveying and data collection to design, revisions and construction staking. When deciding which is faster, don’t look at a single task, but the project as a whole. From this vantage point, modeling may take longer to perform some initial tasks, but this time is made up many times over in downstream activities.

Mark Scacco

About Mark Scacco

Mark Scacco, P.E., is the Editor in Residence for Informed Infrastructure magazine and since 2001 has been an AEC industry consultant. He is the president of Scacco LLC and can be reached at mark.scacco@scaccollc.com.

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