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Crash scene investigations streamlined with new mapping methods
Traffic investigators continue to feel pressure to collect evidence at a crash scene and to reopen roads quickly to prevent secondary accidents. Reopening roads soon after a crash occurs is always a chief goal, but it also cannot happen at the expense of collecting critical evidence at a crash scene. After all, the scene is a fragile snapshot in time that must be preserved long enough to gather sufficient evidence so investigators can learn the likely events that led to a crash. This is even more pivotal if vehicular homicide is involved.
Of the numerous crash scene mapping tools available, total stations are either the first choice of traffic investigators and the only method used, or part of a collection of various measurement equipment. Total stations are pricey, costing upward of $10,000 or more, which for most law enforcement agencies’ budgets in these financially stressed times may be out of reach. However, when considering the number of man hours it can take to map a crash scene using older technology, it’s worth the investment to buy a total station, particularly if it can be used often and even by other divisons within a police department.
Today, various types of total stations are available, all of which are used among crash reconstructionists and investigators. Basically, a total station is an electronic transit integrated with an electronic distance meter (EDM). The electronic transit measures the horizontal and vertical angles. The EDM measures the distance. With these three measurements, the total station calculates the slope distance to, and the elevation of a point in 3-D space, such as the start of a skid mark.
Some models of total stations have internal electronic data storage to record distance and horizontal/vertical angles, while others can write these measurements to an external data collector, such as a hand-held computer. The benefits of total stations are unsurpassed range, speed and accuracy of measurements, and high efficiency.
The types of total stations include: Reflectorless Total Stations: This total station does not use a prism. It can measure a slope distance, for example, without a prism or someone standing over it. This prismless device can measure to certain objects from virtually right up against its scope to several hundred or even several thousand feet away from the reference point location. Robotic Total Stations: A newer type of total station that allows the operator to control the instrument from a distance via remote control. This removes the need for an assistant as the operator holds the reflector and controls the total station from the observed reference point. GPS Total Stations: The latest category of total stations. A key advantage is that GPS total stations do not require a direct line of sight to determine coordinates. A GPS total station is based on full integration of satellite signals. This allows it to provide high accuracy and low power consumption, as well as the ability to measure very long distances. GPS receivers on total stations are equipped by a built-in radio modem.
Minot, N.D. Police
The Minot, N.D., Police Department is realizing major benefits from using its GPS-equipped Sokkia total station. The total station was purchased by the department’s bomb squad, although it also is used for measuring accidents and crime scenes. “The purpose for buying the GPS total station was for speed and accuracy of mapping a scene,” Sergeant Jason Sundbakken explained. “It allows you to go through a crime or crash scene so much faster than our previous units.”
Minot PD previously used laser systems to map crash scenes, which required two people and absorbed about two hours. Now, using the GPS total station, investigators can map scenes in a half hour to an hour. Although the department has a variety of crash scene mapping tools, the Sokkia GPS total station is the predominant tool used.
“The GPS (total station) cuts our investigation time in half, which allows us to open roads and get things moving a lot faster,” Sundbakken said. “We like to be able to close the road to protect any evidence that might be at the scene in that section of the roadway, so we’ll divert traffic around it.”
The thorough mapping accomplished with the GPS unit enables detailed crash scene diagrams to be generated. Sundbakken uses Google Map-generated satellite photos of crash scenes to overlay on diagrams provided by investigators. In doing so, he said, “I am able to show the shoulders of the road that were measured, and all the lanes. Everything measures and matches spot-on.”
Stow, Ohio Police
With deepening budget cuts among law enforcement agencies, it is becoming more difficult to provide the resources and equipment needed to investigate the ongoing wave of serious injuries and fatal accidents that occur on roadways. Although state police or highway patrols traditionally have helped municipal police departments with crash scene investigations, strained resources now mean it could be hours or days before they respond to crash scenes.
Police departments in counties of some states have decided to combat the budget crisis by pooling resources to form special crash response teams. Participating cities must usually offer an officer who can provide a specific service at crash scenes, such as photography or scene mapping. In exchange, the special team of crash investigators will respond to crashes in these cities’ jurisdictions. The benefits are a wide range of expertise and skills, objective investigations, and the latest in crash investigation techniques and equipment.
The Stow, Ohio, Police Department has been participating in a crash response team serving its county, and results have been rewarding. Prior to the response team’s formation, Stow PD would struggle to provide adequate manpower to investigate crashes, even tapping officers from the next shift to help out. Otherwise, it was just one officer trying to investigate the crash scene.
“There was never any peer review for his actions,” Lieutenant Mike Titus recalled. “The investigating officer was out there with a tape measure to reconstruct what happened. Now, there’s a team of people who are all at the same level, and who have much greater resources,” he said.
The crash team uses a variety of equipment and investigative techniques, including total stations and laser systems for scene measuring and mapping, digital cameras for evidence collection, and even “Black Box” downloads from passenger and commercial vehicles so that data can be analyzed. The equipment and the skilled professionals who use it help to provide an independent view and investigation for crash scenes.
Total stations are the predominant measurement and mapping tool used at crash scenes given their ease of use, accuracy, low power consumption and mobility. They are particularly helpful for lengthy crash scenes where hundreds of feet may need to be mapped to create a meaningful crash diagram.
Utah Highway Patrol
The Utah Highway Patrol handles roughly 250 crashes a year, which is why it deploys an arsenal of 17 Topcon 3100 Series Reflectorless total stations for its investigators who are stationed throughout the state. By having so many total stations, investigators do not have to wait for equipment to arrive and so can begin measuring and mapping crash scenes immediately.
The reflectorless models, which have built-in data collectors, work well since Utah has a large number of rural areas with long crash scenes. They enable investigators to map scenes quickly and easily. And the reflectorless total stations do not require an officer to be in the roadway while a crash scene is being mapped, which helps keep investigators at a safe distance to complete their work.
According to Chuck Veppert, president of the National Association of Professional Reconstruction Specialists (NAPARS), reflectorless total stations allow the user to aim the total station beam directly on the piece of evidence so it reflects off the roadway, edge line, tree, pole or gouge mark. This means the operator does not have to be in the roadway to map the crash scene.
The GPS and robotic total stations do not give this same kind of safety element. “They require you to take the receiver to the point that you’re shooting,” Veppert said. However, user safety is increased due to the time savings, and quickness and accuracy of data capture with GPS and robotic total stations as investigators will not have to spend too much time in the roadway.
Safety Always Paramount
The main challenge with crash scene investigation is safety, Veppert argued. But time is also a factor, which means investigators must balance the need to collect enough evidence from the crash scene with the pressure to prevent lengthy road or lane closures that can cause traffic to back up.
The new breed of total stations allows ample crash scene data gathering within short timeframes. These total stations can shoot, in reflectorless mode, for example, better than 1,300 feet. “When I first started (in crash reconstruction),” Veppert recalled, “we were lucky to get 100 to 150 feet.”
The new total stations can measure scenes more quickly and accurately. Veppert added: “You can get more shots accomplished out on the roadway without having to have a prism out there in the roadway.”
Bob Galvin is a Portland, Ore.-based freelance writer who reports on various law enforcement technologies and products.
Published in Public Safety IT, Nov/Dec 2010
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