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Home arrow Archives   The American Surveyor     

Streamlining Accident Investigation Print E-mail
Written by Larry Trojak   
Friday, 15 April 2016

A 3.948Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

The push to increase the speed and accuracy of accident investigations--and improve the safety of the personnel gathering the data at the scene--is an ongoing one, driven by research showing far-reaching benefits of doing so. Consider the following: closing three lanes of an interstate like I-35 in any of the major metropolitan areas it traverses (from Minneapolis to San Antonio) can adversely affect that area to the tune of $45,000 an hour. Literally adding insult to injury: if a major highway incident is ongoing for an hour, there is an 85% chance of a secondary collision as a result of traffic backup. With that in mind, the cleanup needs to be fast, the evidence/ data gathering effort has to be accurate and workers at the scene must be kept safe--a tall order to be sure. But, as companies like Steve McKinzie's CSI Mapping have found, technology, including the use of GNSS-based equipment, is changing the way things are being done at such sites and, in a whole lot of cases, bringing that tall order down to size.

From Patrol to Public
Wearing the hats of both private practitioner and a former Kansas Highway Patrolman, Steve McKinzie brings a unique perspective--and a wealth of experience--to accident scene investigation. In the quarter century he's been reconstructing crashes, McKinzie has witnessed significant change--moves largely driven by advances in technology.

"When I started this business, the overall challenge facing any accident reconstruction professional was finding ways to improve how physical evidence was being documented," said McKinzie. "That meant improving not only our accuracy during the data documentation process, but also how quickly we could do it. Today, we use total stations, laser scanners and GNSSbased instrumentation such as rovers, bases and receivers to do the work that used to be done with a measuring wheel or tape measure and hand-written notes in a pad. As a result, the how of accident investigation work has been streamlined, and now, using the data captured at the scene, in most cases, we are better at answering why it happened."

Time is of the Essence
There is a real motivation for wanting to improve efficiency in the data documentation facet of any investigation. The longer it takes to collect and document data, the greater the risk of evidence being inadvertently destroyed.

"When traffic is backed up for miles and the push is on to get things moving again, something has to give--and most often it's the evidence," said McKinzie. "Some physical evidence may only last hours; it can be destroyed when the fire trucks arrive. So it is imperative that things get done quickly, accurately and safely."

With that focus in mind, McKinzie was recently consulted by a Federal Highway Administration (FHWA) contractor to examine the emerging technologies that can be beneficial in improving what's known as quick scene clearance (QSC). As part of that study, he looked at the broadest possible range of techniques and technologies --everything from tape measure and roller tape, to different total station approaches (infrared measuring to a prism, reflectorless, robotic, hybrid), to GPS, to photogrammetry and laser scanning.

"Another overriding goal of this effort was to improve the safety of first responders at a crash site," said McKinzie. "It's no secret that there are people getting killed trying to help others. So the more quickly we can get them to the site, get the site processed--rendering aid, removing injured parties, collecting and measuring physical evidence, extrication of the vehicle, final cleanup, and so on--the faster we can get the flow of traffic back to normal and reduce the chance of secondary collisions."

Test Results Are In
One of the things that was looked at closely in the study McKinzie headed up involved asking: "In employing this technology, does the user have to get in the roadway and exposed to traffic?" Not surprisingly, a measuring wheel and tape measure were expected to score very low because of the user's high exposure to danger.

"Similarly, using an infrared total station did not fare not much better because the rod person has to be out where the physical evidence is," said McKinzie. "Even though there might be road or lane closures, that doesn't necessarily constitute a safe environment. As we see on the news all too often, people drive through cones, around fire trucks, into police cars, and so on."

According to McKinzie, he found some of the overall results a bit surprising. The Topcon GLS-2000 laser scanner they tested, while very effective, scored lower because of the time needed to scan (due to multiple movements of the instrument), low reflectivity from the vehicles' chrome and glass, and an overabundance of data. Terrestrial based photogrammetry also didn't fare so well because of its distance limitations and the traffic exposure factor.

"A Sokkia SX robotic total station scored high even though the operator is still exposed to a level of danger while he or she is collecting evidence," said McKinzie. "But, because the instrument is so fast, the overall exposure time is lower--so it did well. A Sokkia CX-105 reflectorless total station also fared very well but, because it can't see the other side of a tractor trailer, it has to either be moved or personnel have to wait until the debris and the vehicles have all been extricated from the scene and then measure the physical evidence."

To address that last issue, McKinsey has advocated using an inverted fluorescent spray to paint spots on the pavement in the location at which they would have put the prism pole. "Then, after the vehicles are removed from the scene," he said, `the roadway can be opened and the crash investigation team can come back and shoot the physical evidence reflectorless from the side of the road without ever having to step out into traffic.

The technology that showed the most promise is an unmanned aerial system (UAS) or drone. McKinzie said the fact that it can be launched at the crash site and fly the typical 100-foot wide by 2,000-foot long path--while producing centimeter grade accuracy--in 5-10 minutes is exciting. "And the personnel exposure issue is totally removed from the equation," he said.

Best of Both Worlds
Because of its Kansas City-area location, CSI Mapping works regularly with the Missouri Highway Patrol to continue developing and refining its GNSS program. With that in mind, one of McKinzie's focuses of late has been to find a solution that is more adaptable to the already techheavy cruisers its patrolmen drive.

"The Missouri Highway Patrol routinely uses GNSS to measure crash sites, as long as they can get a cell signal out to a MoDOT reference station," said McKinzie. "But there's no denying that carting around such bulky equipment hampers their efforts. So we worked with Sokkia to find them a good compact workable solution and got it in the Sokkia GCX2 receiver, a screw-together two-meter pole and a Sokkia S-10 mobile field controller. The impressively tiny package replaces two huge orange cases, a wooden tripod, a long pole and a couple of prism bags. An officer can put this in his car and as long as he has a signal available, rarely a problem given MoDOT's extensive reference network, he has dime-sized accuracy."

In work it conducts for the Highway Patrol directly, CSI Mapping has helped enhance both the speed and accuracy of its efforts through the use of hybrid positioning technology--essentially marrying their optical system with GNSS.

"If we are investigating the crash of a commercial vehicle and a car, for example, our Sokkia DX total station is positioned in a spot that is safe, yet able to document the largest amount of physical evidence. Ordinarily, for areas which it cannot reach, it would have to be moved or re-sectioned back into the map. With the hybrid system, however, we can simply switch over to GPS and, with RTK accuracy, keep mapping without even having to see the total station. That easily reduces the 15 to 20 minutes it takes to move and/or re-section. And because the total station is robotic, it is always operating in tracking mode so we can map as fast as we can walk."

Away From the Scene
Currently electronic documentation of data from the Sokkia GCX2 is handled using Topcon MAGNET Field software. A map is then processed, first as simple 2D line work, then, if necessary, enhanced to 3D in either iMap 360 (formerly called MapScenes Forensic Cad), CrashZone, Ares360 or Visual Statement.

"Normally, the majority of maps that are produced stay in a 2D world," said McKinzie. "All that is needed is a flat map that goes over a piece of paper and becomes part of a report published to the public. However, if there is a case in which, say, someone is trying to assess sight visibility distance, that can't be done with a 2D map, you need that 3D model and that's where we come in. We go back to the scene of the accident, create the 3D model of the roadway using either a Hybird station, GNSS or scanner, answer any questions about physical evidence and vehicle speed in order to do a Dynamic Sight Distance Analysis (DSDA) to determine where things were as the two (or more) parties involved approached each other."

Once the surface model is created, the reconstruction tells McKinzie and his team where the collision occurred, how far each vehicle moved post-impact, what the dynamics of that phase of the collision were, and more.

"We are then able to calculate the speed of the vehicles at impact," he said. "From that data we are able to create the DSDA. We `drive' the vehicles over the roadway model we created at those known speeds and, from that, are able to see what each driver had available to him to see."

Making Converts
McKinzie and CSI Mapping's time is divided, with the bulk of their efforts doing work like that described above and the rest spent helping educate accident scene investigators around the country about the technology that is available to help them do their jobs in the safest most expeditious manner possible. Because the technology does not come cheap, it is rarely an easy sell.

McKinzie said a typical scenario has a Patrol Commander asking: "What will I gain by spending tens of thousands of my budget dollars on equipment designed to minimize a loss, when that loss does not directly affect me or my department's budget?"

"The answer I give that chief," he said, "is that, over the ten years he was commander and his teams were equipped for this kind of work, he saved millions of dollars in closures that were either avoided outright or minimized, and he made the highways safer--possibly even saving lives in the process--by clearing things up quickly and eliminating secondary collisions. That's a pretty nice legacy."

Larry Trojak of Minnesota-based Trojak Communications, is a freelance marketing content specialist. He writes extensively for the geopositioning, utility, aggregate processing, recycling, construction, and demolition markets.

A 3.948Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

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