Posts

3D laser scanning revolutionizes construction site accident investigation and evidence collection

In early October 2012, several construction workers were killed or injured when the Miami Dade College parking garage collapsed like a pancake, trapping a then-unknown number of workers inside (See http://tinyurl.com/9956xae). Some survived, but some did not.

Post-accident site investigation

Since this tragic loss of life, injury, and property damage, lawyers have no doubt already begun what will be expensive and lengthy litigation. The owner, architect, engineer, contractor, subcontractors, construction workers and their families will all play a part.

The evidence may be sifted and sorted for years before any judges or juries hear about what happened on that fateful day.

Ideally, each party would have ample opportunity to investigate the site, take measurements, and form opinions as to what happened. However, this was not an option in Miami.

Workers needed to be freed. The structure’s potential for further collapse endangered all those around it. The owner had a dangerous pile of rubble where a new parking garage was supposed to stand. Certainly, nobody wanted to preserve site conditions for any length of time.

So, how can evidence of existing site conditions be preserved forever? 3D laser scanners were dispatched to the site immediately.

From onsite scan to a 3D model on your computer

Similar to traditional surveying, 3D laser scanners are set-up on tripods and use light to precisely measure their surroundings. But whereas traditional land surveying instruments take only one measurement at a time and need a reflector to return the light, 3D laser scanners take millions of measurements of everything that they can “see”  within 300 feet.

This data is collected in a matter of minutes and the instrument can be set up as many times as necessary to see the entire site. Technicians then convert this raw information into a 3D model.

Lawyers and their experts can use this model to return to the day of the accident at any time.  They can pan and zoom around the model to find any desired vantage point. Any angle or distance can be measured and re-measured.

Collecting quality evidence

After any given construction accident, investigators take photographs, make measurements and sketches, and interview witnesses.  However, even the most seasoned investigator can miss critical details due to time constraints, site access, or simple knowledge of the facts.

Once the site is cleaned up or altered in any way, the evidence is spoiled. However, 3D laser scanning allows investigators to return to the site at any time to retrieve missed or forgotten details.

Additionally, the evidentiary quality of 3D laser scanning data far outweighs traditionally collected evidence. Photographs provide only a single 2D perspective and each detail must be specifically targeted. Manual measurements are subject to observational and recording error.  Witnesses certainly cannot permanently remember every visible detail, especially in the wake of a tragedy. 3D laser scanning overcomes all of these limitations.

Full access to the site is often limited, for example, from the danger of additional collapse and loose rubble around the parking garage in Miami. This problem is also overcome with 3D laser scanning, as it uses light to measure from a distance. Anything that can be seen can be scanned and recorded for later review.

Using the model at trial

3D laser scans are not new to the courtroom and readily pass muster under evidentiary challenges. Foundation for entering a 3D laser scan on the record can be laid by a professional land surveyor, but courts nationally have allowed scans based on the testimony of laymen who were simply certified to use the equipment.

At trial, 3D laser scans provide unparalleled demonstrative exhibits. Judges and juries will no longer need to travel to visit a site.

As noted by Lt. Warren Hamlin of the Knox County Tennessee Police Department, “It’s almost like taking the jury right to the crime scene. We can show pictures all day long, but when you’ve got a panoramic view that shows exactly how it looked and where everything was, that’s a much better depiction than a photograph. … So, if a guy says, ‘I was standing in that corner,’ you could create a viewpoint exactly where his head would be and look around the model and tell whether, yes, he could see that, or, no, he’s lying.”

###

David Headrick has over 14 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, focused on developing and managing the company’s 3D laser scanning department. Contact him at dheadrick@lasurveying.com.

An armed robbery, a high speed police chase and…laser scanning?

Sometimes I don’t have to look past the front page of the local newspaper to see a good example of laser scanning in action.

Tragically, there was a police-involved shooting in Cobb County, Georgia, this past weekend, as reported by the Atlanta Journal-Constitution. The suspect allegedly robbed a gas station and then led the police on a high speed chase. The chase ended on I-75 when the suspect pointed a weapon at the police officers and was shot dead.

This was a very unfortunate incident, but the impact on the community was far lessened due to the outstanding work of the Georgia Bureau of Investigation.

The shooting and subsequent chase left many cars wrecked and damaged and, ultimately, the interstate was forced to close temporarily. As you can imagine, this was not a calm situation.

The GBI dispatched their laser scanning team to the site to set-up and scan the area to document the evidence both known and unknown at the time. They also generated 3D photography to further document the area in its entirety.

Using this method, they not only saved time, but were also able to quickly collect the data that would be necessary if the case were to go to trial.

So why use laser scanning to document a scene like this?

First, consider the sheer size of the scene. In this case, the area of study was larger than a football field. Without scanning, investigators would have had to take multiple photographs and make measurements with total stations that shoot one point at a time or worse, measure with 100 foot-long measuring tapes.

This takes much more time, requires more people, and creates much more chance for errors. The errors could be wrong measurements or even missed objects.

When you combine the laser point cloud data with the photographic data, the measurements and the scene become much more intuitive and obvious. You can place the evidence markers by the evidence within the scene and the scanner automatically picks them up.

Instead of making and recording many different angles and distances, you simple put in the points per square foot you want to capture into the scanner and in about 15 minutes, you have a completed scan with photography.

You can look at the scan and very clearly see the markers and measure from any object in the scan to any other object in the scan. So, if you need to know how long a skid mark is, for example, you would just click two points – one at the beginning and one at the end – and the measurement would be instantly generated.

With laser scanning, time at the scene is used to locate and mark the evidence and important points in the scene. All critical measurements can be made offsite after the scene is moved and the traffic is moving again.

Here’s the most important part: If you need information about the scene, but did not know it at the time of the scan, all is not lost! If it exists in the scan, you can make all the measurements you need to document the new (previously unknown) evidence.

More and more, laser scanners are being used to document crime scenes across the country. District attorneys like the scanned data because they can easily view it.

Scanned data is totally objective in that it collects the whole scene. It is easy to put a point down on the ground every square inch so that the coverage of the site is complete. Additionally, the fact that no one has to decide what measurements are made in the field before they release traffic is very important.

Judges like the data because the jury does not have to visit the site to understand the scene. Instead, they can simply view it in 3D on a computer screen without leaving the courtroom.

Laser scanning also saves time and money. Traffic still has to be stopped for an investigation, but if not for laser scanners, it would be stopped longer and there would be less information collected.

###

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 tjones@lasurveying.com or visit www.landairsurveying.com.

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.

Structural Integrity

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.

Settlement Monitoring

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 tjones@lasurveying.com or visit www.landairsurveying.com.