Surveying the Scene

GPS improves accident reconstruction for Sparks, Nev., police.

by / September 7, 2006 0
When Ron Laylon volunteered more than five years ago to measure and reconstruct a motorcycle accident scene for the Sparks, Nev., Police Department using a surveyor's tool, he had no idea what he was getting himself into.

Laylon, a global positioning system (GPS) specialist at the Sparks Geospatial Technologies Office, employed a survey topography tool commonly used to map manholes, catch basins and fire hydrants to gather measurements needed for the reconstruction. The tool -- Leica Geosystems' SmartStation -- proved so effective that the police department roped Laylon into using it for every major accident reconstruction thereafter.

But that's about to end. The Sparks Police Department finally found $41,000 in its budget to purchase a SmartStation of its own. Laylon is now training Sparks police to use the device.

"We did it here in the office as just a favor," said Laylon, who occasionally was awakened in the wee hours of the morning by police officers to map accident or crime scenes. "We've been trying ever since then to put it in their budget and buy their own equipment. It took five years."

The 15-pound survey device lets Laylon record measurements and reconstruct an accident scene in 20 to 30 minutes. Before the SmartStation, officers used a 300-foot steel tape measure, a pencil and paper to create a diagram of the accident. It was time-consuming -- the process took approximately three hours -- and not very accurate.

Traffic Officer Shane Minick has been assisting Laylon and is learning how to operate the technology. "It's much quicker, so we get our roadways open a lot faster with the major accidents that shut down travel," Minick said.


Eliminating Guesswork
Before implementing the new technology, officers took measurements of all vehicles involved in an accident, and any other evidence or debris at the scene. Then they plotted the data on paper or an aerial photo to create a diagram.

Officers obtained aerial photos -- taken every two years by the city -- of the location from the Geospatial Technologies Office and added their illustrations to the map as evidence. There was a lot of guesswork involved in developing the diagrams, Minick said, but the SmartStation removed that guesswork.

With the system, officers record the location of all evidence with GPS that is accurate to one one-hundredth of an inch, Minick said. "When we take the points from the GPS and we overlay it on the city maps, we can take that to court and the jury can get a visual of exactly what that roadway looks like rather than a bunch of dots and lines."

Laylon once found himself in court in a civil case regarding an accident, explaining to an attorney how the technology worked. "He didn't believe it at first. It's like magic to most people. I had to explain to him on my computer how it works. By bringing it back to life with photos you see in front of you; it brings [the scene] back to life," he said. "Normally with the traditional method, you just see lines and points on a white piece of paper."

The SmartStation has two components. One is basically a survey gun called the Total Station, which doesn't include satellite technology, but can be used inside of homes and buildings to re-create crime scenes. The other component, the GPS rover, sits on top of the Total Station and geo-references evidence at the scene.


"GPS on a Pole"
"The rover is the GPS unit," Laylon said. "It takes measurements and it can be mobile. Everything you see through the survey gun and take a shot of is a GPS point. You can sit in one location with the SmartStation and shoot multiple points without moving your instrument."

It's essentially GPS on a pole, Minick said. "We walk around and take different shots of whatever we need to."

That may be curbs, roadway lines, debris, potholes, locations where the vehicles collided -- anything that might lend relevance to the case.

"You walk around the accident, and whenever you sit to take a point of reference -- like vehicle one, left bumper -- you have a code that's entered, then you push 'occupy' and it takes a shot of that bumper and stores the GPS coordinates," Laylon said. "Otherwise you'd have to use a reference point on something, and you'd have to use a tape measure, a roll of tape and spray paint and try to figure out where everything is. This takes the guesswork out of it. What we do with GPS is a lot more accurate than trying to walk a straight line with a roll of tape or a tape measure." The GPS coordinates are downloaded right onto the aerial photo map.

All the GPS points are displayed on a screen and stored in a CompactFlash memory card. Minick said if a case went to civil trial later rather than sooner, the technology can re-create the scene, and a better case would be made than with previous methods.

"If they changed the design of the roadway years from now and this [case] makes it into civil trial in five years, and they want us to go back out and put the vehicle back in place, it won't matter what the roadway looks like now. All those GPS reference points will still be the same."

The SmartStation looks a bit like a space-age robot and can be a little intimidating at first. "It's not easy to use when you first start," Minick said. "But once you learn the mechanics of what to enter and what you're looking for, it all starts to fall into place."
Jim McKay, Justice and Public Safety Editor Justice and Public Safety Editor