3D Laser Scanning: The Best Way to Preserve Evidence on Construction Site Accident Scenes
Q. What do cranes collapsing in New York and Missouri and a parking garage collapse in Florida have in common?
A. 3D Laser Scanning was used to capture and preserve evidence on each of these accident scenes.
Long used by criminal prosecutors, 3D laser scanning is rapidly working its way into the world of civil litigation. The more complicated the environment, the more value 3D laser scanning can add to site preservation and collection of evidence.
This technology is particularly suited to construction site accidents because they are some of the most complicated environments that litigators face.
Dynamic and ever-changing, construction sites can seldom be preserved for the timeframe that it takes litigants to get to court, much less conclude discovery. Similarly, due to the complicated events on a construction site, it can be difficult to capture all relevant evidence and accurately demonstrate witness lines of site and other perspectives.
3D Laser Scanning overcomes all of these difficulties.
How it works
3D laser scanners are set up on tripods and use light to measure and record the horizontal and vertical position of everything they can “see.” They capture data from each setup in less than five minutes and are moved around to different positions to collect data from every angle.
This data is used to produce a 3D world that can be visited by lawyers and experts at any time for site analysis and data collection. This data can then be turned into demonstrative exhibits for the Judge and jury.
Traditional data collection vs. 3D laser scanning
Site preservation of a construction accident scene is typically done by one of the following methods:
1. Hand-drawn site sketches on 2D blueprints, plus 2D photographs
2. Land surveying total-station measurements
3. 3D laser scanning, plus 3D spherical photography
Hand drawn sketches based on handmade measurements are commonly used to provide rudimentary 2D diagrams for use in litigation. However, in addition to providing two instances in which human error can be introduced, site sketches are time-consuming and invariably incomplete. Photographs certainly help paint a picture for the Judge and jury, but parts of the picture are lost in translation.
A land surveying total station increases the accuracy of a site sketch. However, each point must be known at the time and deliberately collected. Once the site is altered, there is no opportunity to collect additional data. Plus, the limited number of points collected by this method makes constructing an accurate 3D model difficult, and thus, less likely to be admissible in court.
3D laser scanning addresses all of the inaccuracies and inefficiencies by providing fast, detailed, accurate, and complete information of even the most complicated environments. Perfect as-built information can be reviewed and analyzed at any time without the need for a site visit.
Lines of site from any point can be reconstructed. With the addition of spherical photography, the virtual world is indeed a perfect representation of the site.
New tools provided by 3D laser scanning technology
3D laser scanning also gives litigators new tools that were previously too pricey or just unavailable. For instance, lawyers and experts can now easily:
· Visit the construction site from anywhere in the country
· Virtually walk around the construction site and enter any building
· Customize viewpoints to simulate those of witnesses and actors on site
· Overlay scanned data onto photographs and measure the distance between any points
· Preserve data that would not have been collected upon original inspection
· Preserve data from inaccessible areas (e.g., ceilings, unsafe areas, remote locations)
· Create a 3D model that is accurate and admissible
· Create video fly-throughs of the job site for the Judge and jury, including animation simulating the actual accident.
Crane accidents – Crane accidents are, unfortunately, a relatively common occurrence. Cranes have completely collapsed, killing and injuring construction workers in New York City and Bellevue in 2013 and Miami and Kansas City in 2008.
After these accidents, nobody wants to leave the site intact. Rescuers need access. OSHA wants the site stabilized. Owners and contractors want to continue with construction. 3D laser scanning quickly collects evidence for litigants, allowing the site to be mediated without risking spoliation of evidence.
Additionally, these sites are unsafe until the failed structural members can be removed. For instance, after the Missouri power plant crane collapse, OSHA erected barriers to prevent anyone from entering the scene of the collapse. However, since 3D laser scanners take measurements of anything visible, forensic site data was still able to be collected.
The 3D nature of the data preserved allows litigants and their structural engineering experts to make more accurate theories about the mechanisms of failure. They can work backwards to determine the causes and orders of failure that led to the collapse. It also works to disprove claims made by others.
Miami parking garage collapse – In October 2012, a parking garage being constructed for Miami Dade College collapsed on itself. Each floor collapsed on the one below like a stack of pancakes, killing and trapping workers inside.
Obviously, this site needed to be cleared to locate victims, address unsafe conditions, and finish the construction. Within 24 hours of the collapse, a 3D laser scanning crew was onsite. As a result, existing site conditions were preserved so that rescue and demolition could proceed.
3D Laser Scanning is the superior method for preservation of evidence on construction site accident scenes.
David Headrick has over 20 years of experience in the surveying, engineering, and legal industries, both as a project manager for LandAir Surveying and as a lawyer in private practice. He has represented numerous land surveyors, designers, architects, contractors, and other industry professionals throughout his career. Today, David serves as an executive and project manager for LandAir Surveying Company, Inc., focused on developing and managing the company’s 3D Laser Scanning Division. Contact him at (865) 599-0148 or firstname.lastname@example.org. View his LinkedIn profile here.