3D Forensic Scans: Three civil applications
In my travels along the 3D laser scanning superhighway, I’ve spent a lot of time talking to criminal forensic experts. This group was one of the earliest adopters of laser scanning technology and I’ve had the pleasure of meeting agents with the FBI, the Secret Service, and even generals and admirals who are familiar with its capabilities.
In my experience, the most advanced groups in the specific application of the technology to prevent and investigate crimes have been the Secret Service and Scotland Yard. Both have programs written specifically to analyze the data and use it proactively to protect kings, queens and presidents.
High definition scanning allows you to check every site line – not just one or two.
Our firm has worked on several “criminal” projects over the years – some supporting the prosecutors and their evidence and others supporting the defense teams and their clients. But we also work with the litigation and documentation of forensic evidence for civil or construction projects.
Many jobs require our expertise to go out and document the existing conditions of a site. We have literally traveled from Montana to Texas to Georgia working with clients on various cases.
Perhaps the most famous civil forensics projects were the scans used for analysis of the World Trade Center attacks and the Minneapolis bridge collapse. On both of these projects, the scan data after the destruction of the structures was used to determine exactly what caused the failure.
Obviously, in the World Trade Center, the initial impact of the plane created the fire ball and damage, but it was the fuel in the plane that heated up the beams in the structures and ultimately caused them to fail, each floor collapsing on the one below as the entire structure came down. The melted beams were documented with laser data.
One of our first projects was scanning a three story parking deck. During the initial walk around, we could tell that the deck – even though made of concrete – was warped and some of the columns were out of plumb. Other areas were cracked and stressed.
We produced plans and models with the data and structural engineers were able to determine that the structure was unsafe. Because of the density of the data sets, engineers were able to look at all surfaces rather than a few strategic spot shots before making their final determination.
By being able to look at the line of the vertical columns through the building, engineers could tell that the cost to fix the failing structure would be much larger than building new.
Large Vessel Analysis
We also had another project where we were asked to scan a large containment vessel that held various types of liquid depending on the product being produced or stored.
In this type of investigation, we were able to document that a certain vessel was out of plumb, warped or bent. This information was then used to determine if the vessel was safe and, if not, how and when to replace it before a failure occurred.
Being able to monitor when and how much something is settling is very important to a property owner. We recently worked on a very large project in the western United States that involved a large platform used for loading and unloading products.
In this case, one long section had settled much more that the specifications allowed and had begun leaning at a dangerous angle. The engineer showed me previous surveys and I asked him why they needed us if they already had survey data on the structure.
He explained how the parties involved were having difficulty understanding the traditional survey data and its implications.
Once we scanned the platform in 3D and modeled it, it was quite obvious to everyone how badly the shape of the original structure had changed, as well as the principal cause of the failure. This helped move the group discussion from, “There isn’t a problem,” to “How do we get this fixed?”
We have completed many other civil forensic projects for engineers ranging from dam failures to vertical wall failures and even construction slabs that were not level or flat. The common element in all of these projects was that the use of laser scanning technology was the perfect tool to document the conditions and the data was easy to interpret and model into a visual form that everyone could understand.
Forensic scanning of crime scenes will continue to grow, as will the 3D laser scanning of complicated civil projects. 3D laser survey data is becoming mainstream in analyzing the cause of catastrophic civil construction failures. If you know how something fell to the ground, you can usually tell what failed first.
Tate Jones has over 40 years of experience in land and aerial surveying and was one of the country’s earliest adopters of 3D laser scanning technology. A nationally recognized expert in the field of 3D data capture, he has worked with hundreds of clients in the engineering, architectural and construction industries. Contact him at firstname.lastname@example.org or visit www.landairsurveying.com.