Mapping choices abound as traffic and crashes mount

Get smart about technology choices when mapping crash scenes


There are several software programs which use the technology of close-range photogrammetry. These programs vary in price and method used to ultimately determine the measurements needed by a reconstructionist.

The iWitness photogrammetry software program from DeChant Consulting Services in Bellevue, Washington, is the most recent entry in this crash scene mapping category. iWitness is specifically designed and optimized for accident reconstruction and forensic measurement, making it the program of choice for agencies like the Florida Highway Patrol.

"I spend far less time sweating out at the scene because I can map it significantly faster compared to other measuring methods I've used in the past," says senior traffic homicide investigator Cpl. Dave Templeton of the Florida Highway Patrol.

There are at least two other photogrammetry applications — Photomodeler from Eos Systems in Vancouver, British Columbia, Canada, and ShapeCapture from ShapeQuest Inc. located in Ontario, Canada. Alternative photogrammetric software programs like these were designed for more general photogrammetry applications, but can still be used to map a crash or crime scene.

Close-range photogrammetry has other pros and cons that are important to consider. One advantage of photogrammetry is that the processing of data is accomplished by the software after leaving the scene. This means that as long as the appropriate photographs were taken at the scene, accurate measurements can still be obtained months or even years later — long after all physical evidence has been removed from the scene. This makes a case for taking photographs of a scene that can be used later for photogrammetry, even if a total station or other measurement method is already being used. Then, if it is later determined that some important data was not obtained at the scene, investigators may be able to retrieve it from the photographs.

It's important for anyone using close-range photogrammetry at a long crash scene to be aware that special procedures are sometimes needed to link the pictures into one mapping project. A typical 6-megapixel digital camera can produce photographs with usable resolution at a range of about 200 feet. Some photogrammetry programs, such as iWitness, have a feature that "stitches" together a series of photographs taken of a long scene to produce accurate 3D measurements.

Funding enhances availability

If the sticker shock for mapping equipment proves too much for the budget, there is financial help available. According to Al Baxter, administrator for the Accreditation Commission for Traffic Accident Reconstruction (ACTAR), "The first stop they should be making is their governor's officer of traffic highway safety." This state government representative should be able to process grant applications to the National Highway Traffic Safety Administration, which offers grant opportunities for technology equipment purchases and other facets of traffic safety.

The grants are helpful if a law enforcement agency wants to purchase just one total station for its officers to share, but cannot afford it.

"The next alternative would be a laser mapping device," says Baxter. "The selling point of getting a total station or a laser, as far as the grant goes, is if you can reduce traffic congestion by opening up a crash scene quicker, or you can get more accurate measurements than some other method."

Also, suggests Baxter, if a municipality is small, "You can work with your detective bureau and public works people to share equipment like a laser. You have this piece of equipment that's available for measuring crash and crime scenes, yet it's good for the public works department if they need to measure road widths or do surveying. It's a multi-sales point, not just strictly for promoting the measurement of crash scenes."

With the ever increase in traffic and accompanying crashes, mapping tools are a necessity for all departments. Considering the variety of technology and funding opportunities available, departments should be able to equip themselves for when crashes need to be investigated. It's time to get smart about crash scene mapping technology.

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