Forensic Investigation

“What happened?” and “Why did it happen?” are usually the first two questions asked of the forensic engineer. Of course, these are often followed by, “How can it be fixed?” And, all too often, “Whose fault is it?” and “Who´s going to pay?”

As specialists in the fields of geoenvironmental and materials engineering and the related field of construction testing, Paradigm Consultants, Inc. is frequently called upon to conduct or assist with forensic investigations to answer those or similar questions. Forensic engineering is generally defined as the application of science and engineering to the investigation of a failure, or accident. Within the framework of dispute relating to construction, particularly within the jurisprudence system, forensic engineering may include investigation of the physical causes of accidents and other sources of claims and litigation, preparation of engineering reports, testimony at hearings and trials in administrative or judicial proceedings, and the rendition of advisory opinions to assist in the resolution of disputes affecting life or property.

Within the construction industry, disputes usually result from unfulfilled expectations of the project developers and purchasers, from errors or omissions of the design team, or from construction or material defects. Non-technical issues, principally time and cost, are frequently considerations, and unanticipated influences such as weather and unforeseen conditions may negatively influence the performance of construction.

In the “perfectly” constructed project, the expectations of the owner/developer are completely understood by the design team and are converted to a clear, comprehensive set of drawings and specifications. After execution of an equitable contract outlining the terms and conditions, schedule, and compensation arrangements, the competent construction team executes the construction according to the design within budget and on schedule. And finally, coming full circle, the expectations of the owner or developer or occupant are met. Unfortunately, in our imperfect world, few projects are perfect. Expectations are not met, designs are inadequate, construction is improper, materials fail, and nature exerts its influence. Whether before, or after calling the lawyers, a forensic engineer is usually needed to provide the technical expertise to investigate and answer the questions.

The process used by the forensic engineer is an adaptation of the scientific method, “the process by which scientists attempt to construct an accurate (that is, reliable, consistent and non-arbitrary) representation of the world.” The scientific method has four steps:

  1. Observation and description of a phenomenon (an occurrence, observation, event, or trend) or group of phenomena, i.e. identify the problem.
  2. Formulation of a hypothesis (a theory or statement regarding cause and effect) to explain the phenomena, i.e. decide on the procedure.
  3. Use of the hypothesis to predict quantitatively the results of new observations.
  4. Performance of experimental tests of the predictions with properly performed experiments, i.e. collect the data and perform the analysis.

It is the fourth step that often is overlooked. Because the experimental tests may lead either to the confirmation of the hypothesis or to the ruling out of the hypothesis, the scientific method requires that a hypothesis be ruled out or modified if its predictions are clearly and repeatedly incompatible with experimental tests. Further, no matter how elegant or desirable a hypothesis or theory is, its predictions must agree with experimental results if it is a valid description of nature.

The scientific method attempts to minimize the influence of the forensic engineer´s bias or prejudice on the outcome of an experiment. That is, when testing a theory, the engineer may have a preference for one outcome or another, and it is important that this preference not influence the results or their interpretation. Another common mistake is to ignore or rule out data (measurements or information) which do not support the engineer´s theory. Ideally, the engineer is open to the possibility that the theory is correct or incorrect. Sometimes, however, the engineer may have a strong belief that the hypothesis is true (or false), or feels internal or external pressure to get a specific result. In that case, there may be a psychological tendency to find “something wrong” with data which do not support the engineer´s expectations, while data which do agree with those expectations may not be checked as carefully.
A simple example will clarify the scientific method.

  1. An observation: My car will not start.
  2. My hypothesis: The battery is dead.

  3. My prediction: If my lights are dim, and if the starter makes a particular sound when I turn the ignition key, then my hypothesis is correct.

  4. My tests: I turn on the lights only to find they are bright. Turning the ignition key, no sound is heard.

Discovering that the battery is not low, you might attempt another hypothesis – “The starter is broken.”
In summary, while the scientific method appears simple and logical, there is perhaps no more complex question facing the forensic engineer than that of knowing, and then explaining, how he or she knows the answers to: “What happened?” or “Why it happened?”