Opportunities in Forensic Mapping

by Bob Galvin, RS

Traditionally, field surveying has been the domain of the total station. But savvy surveyors, whether they’re independent consultants or a large surveying firm, are finding a new application for this trusted tool: law enforcement—more specifically, forensic mapping at crash scenes. Although crash-scene investigators aren’t surveying with this tool, they’re mapping points of physical evidence.

Because the total station is the mainstay of nearly every forensic investigation in Canada, it is increasingly essential for investigators without a lot of forensic-mapping experience to learn how to use a total station, along with the data collector, evidence-collection software, and diagramming program that comprise the standard crash-scene documentation process. Helping them learn the methods of forensic mapping is the Canadian Traffic Safety Education Centre (CTEC) in Edmonton, Alberta, Canada. 

Surveyors are occasionally tapped to help with instruction on the use of total stations. Canadian police agencies, much like the U.S. law-enforcement agencies, have hired surveyors for unique situations, some of which include assisting with forensic mapping.

Teaching Total-station Use

The CTEC had auspicious beginnings. At one point in his career, Dwain Friesen, the center’s chief operating officer, was handling collision investigation and training for the Royal Canadian Mounted Police (RCMP). He left the RCMP in 1995 to join the Canadian firm of Renneberg-Walker Engineering Associates Ltd., which also performs crash reconstruction work.“We put on a collision investigation course for the public [including insurance professionals and trucking firms] and it went well,” Friesen recalls. “Then we formed the CTEC division.”

Today, the CTEC offers forensic, advanced driving, and motorcycle training courses. A variety of collision investigation courses and specialty courses—such as forensic mapping and computer-aided design—are also included.

Friesen is a big advocate of using total stations, having used a tape measure at crash scenes for years that required much more time and presented great danger for officers. 

“It was a huge hazard,” Friesen said. “We have to balance the interruption of traffic flow with the collection of evidence. So, once the total station was available, it cut down on the amount of time at the scene substantially, and at the same time increased officer safety.”

Another reason the total station is such a pivotal tool for forensic mapping is its ability to collect evidence. Friesen cited an instance years ago in which CTEC learned of a law enforcement agency that was taking some course work through the traffic safety education center and considering purchasing a total station. To help the agency justify the cost of a robotic total station, the center set up a mock scene with three groups of people collecting data: one collecting evidence with tape measures, a second using the distance-measuring capabilities of a laser speed device, and a third group using total stations.

The mock test results were stunning in their contrast. The group using tape measures was picking up about 20 points an hour, which, Friesen notes, is what the center found to be consistent with its collision investigation courses for the tape measure portion.

“With the total station, we were picking up 300 points in the same hour,” Friesen said. “If you only needed to get 20 points, then of course the amount of traffic disruption and risk exposure [using the total station] is greatly reduced. Or, if you’re going to stay the hour, you get so much more data and it’s so much more accurate.” 

Add the data collector and software to record the collected data points, and “you’ve got your scene just about completely mapped before you leave,” Friesen continued. “So, this adds another dimension where if it’s a very serious event you could have a scaled diagram of the collision scene within 15 minutes of getting to a computer. Which is fantastic.”

Given Friesen’s testimonial, it’s no wonder that he requires students to spend a one-week course just on how to use a total station.  Friesen makes sure students follow proper total-station setup procedure. This is all typically followed by another one-week course on how to use the evidence-collection software.  However, Friesen said, “We try to combine these so there’s no disconnect between the two components. Typically, we’ll be working with one law enforcement agency at a time so that the instrument we’re using is the same for every student.”

The Canadian Traffic Safety Education Centre trains students on Sokkia and Nikon total stations. Students’ agencies will have purchased one of these brands, and then depending upon the class size, the center can rent or borrow the total stations from the vendors.

Friesen prefers six students to a class. They must practice with the total stations until they learn how to use them. “When they get bored from this, we know we’ve got acceptance,” Friesen said.

Robotic Total Station Gets Spotlight

Recently, the center experienced a situation that most of us might view as the student instructing the teacher. It involves the Moose Jaw Police Service in Saskatchewan, Canada, which approached CTEC about training some of its officers on a Sokkia SRX Robotic Total Station it just purchased from Brandt Tractor Ltd-Positioning Technology Division. It uses the MapScenes Evidence Recorder and Forensic CAD software.

Friesen had not previously used robotic total stations in his classes, plus he was a bit skeptical. “I wasn’t the biggest fan of a robotic because there [usually] was someone around who could hold a prism rod for you,” he said. Yet, Friesen admits this older method presented difficulties because the prism often came out of level, prompting trips back and forth between it and the total station to make sure measuring would be on target. Once management saw how many hours people wasted on the scene double-checking the target, they better understood why a robotic instrument was a better choice.

Robotic total stations, first introduced in the early 1990s, help reduce overhead and save time because they do not require two operators. They allow the operator to control the instrument from a distance via remote control. This removes the need for an assistant staff member, as the operator holds the reflector and controls the total station from an observed point. The Sokkia SRX series features fully tracking and auto-pointing robotic total stations, with on-demand target reacquisition and reflectorless EDM.

Soon after the Moose Jaw Police Service purchased the total station, it contacted MapScenes for a trainer. Then MapScenes contacted Friesen. Sokkia “came out to introduce students to the total station and evidence recorder, and my part was to take the data collected and use it with the diagramming software program,” Friesen said.

“It was a great experience for the students,” Friesen affirmed. “Working the first two days on the Sokkia really won me as a fan. There was considerable ease of use, and driving it with the evidence recorder flattened out the learning curve immensely.” 

In addition to substantial time savings, the CTEC’s use of total station packages (total station, data collector, evidence recording software, drawing software) has provided some major benefits. First, it has removed all human error from measuring crash scenes and collecting evidence. 

Therefore, accuracy and security of data is ensured. Second, Friesen notes that the time savings with using total-station packages compared with tape measuring scenes simply allows investigators to respond to more incidents.

“It’s all new to most of these people [CTEC’s students],” said Friesen regarding forensic mapping of crash scenes. “It’s a bit of a paradigm shift for them. They’re not leaving a scene with a bunch of handwritten notes,” he added. “So they have to make that jump to believe in the technology.”

Most law enforcement officers will quickly admit that it’s much easier for surveyors to learn the basics of forensic mapping, because surveyors already know how to operate a total station and how to map and collect data points, then build a diagram from them. And even if surveyors don’t plan to pursue a new or parallel career in forensic mapping, they can be a valuable resource to police agencies that might need basic instruction on mapping and diagramming evidence points.
 
Furthermore, once trained by firms such as the Canadian Traffic Safety Education Centre, these police agencies could share their knowledge and training with surveyors aspiring to enter forensic mapping, whose consulting services might prove helpful as well.
Bob Galvin is a Portland, Oregon-based freelance writer who writes on technology trends. His writing covers developments in total station equipment and diagramming and data collection software.

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