Digital decisions

August 2006 » Business
Information technology tools enhance the role of engineering judgment in analysis and design.
W. Allen Marr, P.E.

Information technology tools enhance the role of engineering judgment in analysis and design

The practices of geotechnical engineering and engineering geology require professionals to work with very limited data about a complex environment, where conditions can change radically over a short distance and with time. Geotechnical engineers and geologists use scientifically accepted principles of interpolation, extrapolation, deduction, and inference together with their judgment to extend this limited information to a generalized model of the subsurface conditions at a site.

Typically, we must rely on simplified test devices, conversions, correlations, approximations, and our engineering judgment to deduce the material properties to use in analysis and design.

Today's information technology (IT) tools and systems provide a quantum jump in capabilities. I have been involved with the application of IT for more than 30 years; therefore, it seems appropriate to consider where we are and where we may be going with applications of IT to the geotechnical practice.

Until IT tools become self-replicating and self-improving, they can never replace engineering judgment. Instead of engineering judgment becoming less important, a strong argument exists that it will become increasingly important. The exponential growth of IT tools forces us to think harder about which tools are appropriate to our problem. And the demands on our time taken by the explosion of information and IT tools increasingly pull us further from close contact with the look and feel of the actual site conditions.

Instead of rejecting judgment, we need to better understand what it is and how we use it. Additionally, we need to determine ways for engineers to develop good engineering judgment. I see the role of IT tools as providing us with methodologies to assist in finding and evaluating information, performing analyses to guide our judgment, and helping us present the results of our work to others in ways they can understand.

G.E. process

It is important to understand more about the process of geotechnical engineering—which I have termed the G.E. process—and the opportunities for IT tools to help improve the process.

Geotechnical engineers go through the following five stages in a good geotechnical program: information, analysis, prediction, observation, and evaluation.

Analysis includes formulating design alternatives and testing whether they meet the objectives and satisfy the constraints.

The analysis stage raises questions and identifies gaps and weaknesses in our data and model that may require us to return to the information stage of the G.E. process.

Analysis makes heavy use of deductive reasoning. Engineers have many tools for analysis, with increasingly powerful tools that allow us to get closer to modeling reality.

Prediction combines the results of analysis with our experience and judgment to make a forecast of performance. Within the prediction, we identify key performance indicators (KPIs) that will tell us whether the design is performing as we expected and whether it will fulfill its intended function.

Observation involves the process of taking information from the prediction stage of the G.E. process to establish a monitoring program, obtain the measurements, and verify that the measurements are accurate and truthful. Observation provides us with the true measure of how the site behaves during the course of our work. It consists of visual examinations and measurements of KPIs. The human eye is one of the most powerful observation tools we have. It can reveal inconsistencies in our data and analyses, as well as disconnects between our model and reality. However, the power of vision is limited by the time one can spend onsite; by the inadequate precision of measurement; and more importantly, by our inability to see inside.

We use measurements from instruments to help us overcome these problems.

There are sensors for just about everything one would want to measure about the physical environment. Futurists claim that we are entering a wired world where everything will be monitored and reported anytime, anywhere. The geotechnical profession is getting close to having this capability.

Leaving out observation produces a disconnect in the G.E. process. We are denied the opportunity to assess our prior judgments and to upgrade our reasoning tools. The client also loses the benefits of recognizing unexpected performance early enough to implement alternatives and to limit consequences.

Evaluation combines predictions and observations into a synthesized model of how the site actually behaves. Evaluation answers questions such as: Why did the site behave differently than predicted? What are the implications of these differences? Are future actions required? Did we make a mistake in using our judgment? Evaluation involves an assessment of the analyses, predictions, and judgments made in the first four stages of the G.E. process. It involves comparing observed and measured performance and outcomes to predicted performance and predicted outcomes.

A measurement that is not evaluated soon after it is obtained is useful only to the lawyers and experts doing cleanup work.

Either it shows no significant change and therefore is of little interest to anyone; or it shows a significant change but no one knows about it until the damage is done.

Ideally, every measurement would be evaluated moments after it is obtained and the appropriate action initiated shortly thereafter.

IT tools currently help us in limited but important ways with the evaluation stage of the G.E. process. They can present validated data together with predicted performance in ways that allow us to assess quickly whether further evaluation is required. IT tools offer the potential to combine measurements with predictions to produce a revised prediction of the future. One way to do this is to use mathematical analysis to identify a function that closely fits the measurements over time; then use this function to extrapolate into the future.

Most of today's young engineers are very proficient at applying this type of IT tool to closely fit higher-order functions to a data set, to extrapolate, and then to draw conclusions. However, how many look at the next logical step: What does this closefitting function tell us about future performance? Each of the aforementioned stages of the G.E. process requires the application of critical thinking skills. Research conducted in the education profession has equated critical thinking to judgment; thus judgment plays a central role to every stage of the G.E. process. Judgment is critical thinking and reasoning—arriving at a conclusion from masses of conflicting, contradictory, erroneous, and irrelevant information.

IT tools are providing us with more information and more powerful means to perform analyses. In my view, geotechnical engineers have only begun to absorb them into their work processes.

Nevertheless, new IT tools will not replace the need for good engineering judgment in every stage of the G.E. process. In fact, the opposite will prove true. These new tools and capabilities will greatly expand the information and options available to us and force us to use good engineering judgment more than ever.

W. Allen Marr, P.E., is president and CEO of Geocomp Corporation, in Boxborough, Mass. He can be reached via e-mail at wam@geocomp.com.


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