High-Tech Tools Help Make Sense of Traffic Crashes
Who did what, when and where are critical pieces to understanding what happened in a vehicle crash.
After officers arrive on the scene of an accident, whether it’s serious or not, a report is completed and information such as street names, time of day and names of drivers, is collected.
“When your loved one is killed in a crash, you need answers,” Fond du Lac County Sheriff’s Office Capt. Rick Olig told The Reporter. “And for us to be able to say here’s what happened – good, bad or whatever – they get the truth from us.”
Accident reconstructionists aren’t called for every accident, according to Wisconsin State Patrol Lt. Timothy Huibregste and Olig. But when criminal charges may be appropriate, where vehicle or roadway design may be a factor, or in special interest incidents they are summoned.
“Ultimately what has to happen is someone has to sit in the witness box and explain to jurors what happened,” Olig said.
In order to obtain the most accurate data from a crash scene, accident reconstructionists are equipped with high-tech tools and computer software.
Fond du Lac County Sheriff’s Office Deputy Nick Evans, who works on the accident reconstruction team, said it is typical for investigators to work backward from a crash scene and begin by figuring out the speed of each vehicle at the point of impact. It is easier for investigators to then use other information such as the length of tire marks to determine the vehicle’s speed prior to the crash, he said.
Another tool used by reconstructionists is called an Event Data Recorder, which is installed in most cars. It is used in instances when evidence from the crash scene is not readily available.
The force of impact, air bag deployment, seat belt use, steering wheel input, engine speed, vehicle speed, throttle position and braking status are all retrievable through the recorder. Data taken from the vehicle can be used later in the reconstruction process as a checks-and-balances system, Evans said.
“The data collected gives us a snapshot of what was occurring during a crash sequence,” Huibregste said. “It’s another piece of the puzzle used to reconstruct crashes.”
Almost everything investigators do now involves a computer or some other form of technology.
Among the tools used by the Fond du Lac County Sheriff’s Office to reconstruct crash scenes are a total station and a prism, which help investigators get measurements that years ago would have been obtained with a tape measure and mathematical formulas.
“What used to take three hours can now be done in about 15 minutes,” Evans said. “Technology has had an immense impact on our work and the accuracy we are able to provide.”
Investigators measure the roadway, signs, trees, debris, vehicles, lines in the road, tire marks, gouge marks, liquids or anything else they feel may have affected the sequence of events before, during and after an incident.
Investigators are then able to determine vehicle speed and deceleration, roadway friction, braking abilities of a vehicle and both pre- and post-crash travel paths. Officers also test road surfaces using accelerometers and other sensitive instruments.
“There is a lot of information obtained from tire marks alone,” Huibregste said. “They can determine if the brakes were applied or if a vehicle made a turn in a certain direction. (Reconstructionists) also test the coefficient of friction using the roadway surface to help establish speed estimates.”
Total reconstruction of an accident can take anywhere from 40 hours to several-hundred hours, Olig said.
After all the data is collected, investigators use computer software to diagram an exact map of the crash site and to simulate how the crash occurred. Prior to computer software, investigators had to draw a map of the scene on pencil and paper.
If an outside expert, such as a private consultant hired by a defense attorney, has a different theory than a reconstruction team, it is left to the court system to make a determination in most cases. All reconstruction reports are reviewed by other officers before the report is released.
Defense attorneys often hire outside consultants, but Olig said those experts may not have correct data because they often are not at the initial crash scene.
After a crash is reconstructed, the final report is provided to prosecuting attorneys to determine if there will be charges. These can range from a traffic citation to a criminal charge.
Reconstruction reports are often reviewed by the state Department of Transportation to determine if there are highway design changes that can be made to prevent crashes in the future, Huibregste said.
A 2012 crash that killed an Eden couple and injured their 14-year-old daughter illustrates the complicated nature of accident reconstruction.
Daniel Shea, 24, of Campbellsport was allegedly drunk and texting while driving south on Highway 45 in the Fond du Lac County town of Auburn at about 5:30 p.m. on Sept. 23. Shea is accused of crossing the centerline and striking a northbound car head on. Paul Grahl, 73, and 59-year-old passenger Joanna Grahl were killed on impact, according to court documents.
The Fond du Lac County Sheriff’s Office was called to reconstruct the accident. Olig said investigators have determined that Shea crossed the centerline. Skid marks at the scene show his vehicle crossed into the northbound lane and then back to his southbound lane where the crash took place. The Grahl vehicle, the investigation shows, moved into the oncoming lane to avoid getting struck by Shea when he initially crossed the centerline.