Geospatial Technologies Aid Traffic Accident Investigation
Last month, a neighbor told me that it had taken her five hours to travel from Renton, Wash., to Olympia, Wash., a distance of 53 miles over freeways. The culprit? Traffic gridlock due to accidents.
The story of her commute was harrowing. It was a compelling reason for law enforcement, motor vehicle departments and others to find more efficient ways for documenting traffic accidents so they can keep the rest of traffic moving.
“We help limit road closure time by speeding up the [forensics] process while making it more accurate, and at a higher level of detail, than any other method being used around the country,” says Bryon O’Neil, criminologist at the Clackamas (Oregon) County Sheriff’s Office.
O’Neill goes on to say that his department recently moved to using laser scanners for traffic accident documentation and forensics. He also says that since purchasing that laser scanner, his team has been able to reduce time and staff on scene by 50 percent and that the department has saved more than $73,000 in overtime costs in 32 months.
This doesn’t even factor in the thousands of hours that laser scan forensics technologies can save commuters.
Clackamas County normally uses two people to perform at-the-site forensics laser scans. They set targets and move the scanner, with the data captured by the scanners being admissible in court.
In one case, the department investigated an incident where a Portland bus hit a skateboarder who sustained serious injuries. While it might have been easy to believe that the bus driver was at fault, the point cloud captured at the scene by a laser scanner and the subsequent analysis proved otherwise.
“A skateboarder was on the sidewalk, at the top of the hill, when the bus started its turn,” O’Neil says. “The guy rode down the sidewalk and right out in front of the bus. I created an animation and used the point cloud to verify the driver’s line of sight. I was able to show that it was the fault of the skateboarder – not the bus driver.”
“Laser scanners have helped law enforcement and others with the need to document an accident scene,” says Janice White, director of product management in forensic public safety for FARO, which provides 3D measurement, imaging and realization technologies. “Years ago, they used tape measures and rolling wheels to document accident scenes. Then, about 20 years ago, they made the move to total stations with surveying equipment. Total stations are accurate, but extremely time-consuming because you need one person to operate the device and one person holding a pole at each data point that you are measuring and documenting, and you can only record one data point at a time.”
When compared to total station surveying, laser scanner technology is an efficient option because with one scan, users can capture a 360-degree view of the site without having to go point-to-point. This leaves far fewer data points to measure and record. A single laser scan also only takes several minutes to complete. Thereafter, the scans are taken back to the office where they are “stitched together” into a composite view of the accident scene.
Nevertheless, there are still logistical and cultural barriers in the adoption of laser scanners that many law enforcement agencies must overcome. For starters, there is the issue of technology investment. Many law enforcement agencies have already invested in total station surveying technology. Although total station surveying is more labor intensive and takes longer to complete than laser scanning, personnel are already trained in its methodologies and are doing it regularly.
Second, total station surveying and laser scanning technologies can’t always cover every accident detail. “There are simply cases in traffic accidents where you can’t physically place a laser scanner or other ground-based scanning or surveying technology to document what needs to be documented,” says Lisa Chen, surveying solution manager at Pix4D, a drone mapping and photogrammetry software company. “The distance between two objects might be too small to use a handheld laser scanner. In this case, an overhead drone or doing the measurement manually might be the best approach.”
Next, there is the issue of training. It is easy enough to push a button on a hand laser scanner and start scanning, but the proof of the pudding is when the scans get back to the office. Someone has to be skilled enough to work with the software so that all of the scans can be correctly stitched into a composite view of the accident, without any overlaps. “The process is called registration,” White says. “Someone has to be trained so they know how to stitch all of the scans together and how to handle the overlap.”
Lastly, the evidence from the scan has to be admissible in court. “This makes it very important for law enforcement agencies to continuously inspect and calibrate their scanners and ensure that their equipment is in good shape,” White says. “A question about scanner calibration and accuracy could render the evidence collected by scans inadmissible.”
Despite these challenge points, law enforcement agencies, as well as government sponsored initiatives for laser scanners, are growing.
Courts now routinely accept registered accident site scans into evidence if best practices for documenting traffic accidents and maintaining equipment in good working order are adhered to. Price points for new laser scanner equipment and software are as low as $30,000, and the time saved in the field and the hassles saved for traffic commuters also enter in.
In addition, if you're an insurance company or a private investigator that has a need to document a traffic accident and you don't have the authority to close a road, the time saved in documentation with a 360-degree laser scanner is invaluable.
So, what are the takeaways for law enforcement professionals and others with a need to document traffic accidents?
#1: Pilot laser scanning technology first.
Many vendors will offer a demo or “try and buy” trial option so you can see how the technology will work at a traffic accident scene.
#2: If you decide that laser scanning is for you, start small.
There is a learning curve with the uptake of any new technology. With laser scanners, the training isn’t so much at the accident scene, where two people can record 360-degree scans in minutes with the press of a button. Rather, it is back at the central office, where someone must be trained to stitch together all of the scans into a single composite scene and then register it.
#3: Track your results.
How much time and how many resources is it taking you to document a traffic accident with a laser scanner? How does this compare to your old methodology?
If you start small with one laser scanner, your time and resource benchmarks when compared against those of your old practices are helpful in establishing a projected and realistic return on investment (ROI) for the new technology.
#4: Talk with other law enforcement agencies that have already implemented the technology.
These agencies can tell you the pros and cons—and provide you with insights into best practices and lessons learned.
#5: Always maintain calibrated equipment that is in good working order.
The end goal is to produce traffic accident documentation that is admissible in court. Courts, like law enforcement agencies, are seeking ways to operate more efficiently. They are receptive to admitting scans of accident scenes into evidence, but they aren't going to admit it if there is a question about the accuracy or condition of equipment that was used.