By Jami Badershall,Staff Writer

FARMINGTON – Aaron Turcotte’s notes read like an advanced physics homework assignment. It’s the science of crash reconstruction – formula after formula calculating drag factor, velocity and speed.

But that’s just a small part of what the 25-year-old sheriff’s deputy does to find out what led to a collision and who caused it. As one of about 50 crash reconstructionists in Maine and the only one in Franklin County, Turcotte is called out to crashes, especially those involving serious injuries, fatalities or cases that will be prosecuted.

The work is called crash or collision reconstruction, not accident reconstruction, because rarely is something a true accident. “There’s almost always someone at fault,” Turcotte said. “Almost all collisions could be avoided if people were careful when they drive.”

Often the cause is speeding. “Collision reconstruction helps explain why we have the speed limits we do,” he said. “In a lot of the cases, if a person had been going the speed limit, they would have been able to stop in time” or avoid a crash.

Such was the case on the first crash Turcotte reconstructed after his training and certification were complete in May 2005. An 8-year-old boy had been struck by a pickup and seriously injured on Davis Road in Jay as he rode his bicycle out of a driveway and into the roadway.

The driver locked his brakes and skidded 54 feet before striking the child. It took a total of 137 feet for the truck to come to a stop. Turcotte’s calculations showed that the truck was traveling at 54 mph when the driver first hit the brakes and 42 mph at the time of impact. The speed limit was 35 mph. Using a perception reaction time of 1.6 seconds, Turcotte was also able to calculate that the truck was 127 feet from the start of the skids when the driver reacted to seeing the child.

Had the driver been going the speed limit, Turcotte calculated, he would have needed 82 feet to react and begin to stop the truck when he saw the child, and he would have traveled another 56 feet before coming to a stop. That means he would not have hit the boy.

Reconstruction can also prove that a person wasn’t speeding and wasn’t at fault in a crash even though an initial glance at the evidence might say otherwise.

Sgt. Richard McAllister, the head of the Crash Reconstruction Unit for the Maine State Police, which oversees all reconstructions in the state, had a case in Auburn about 10 years ago. The crash happened at the intersection of Kittyhawk Avenue, which has the right of way, and Hotel Road, which has a stop sign. A tractor trailer was on Hotel Road, and the front of the truck was through the intersection when an elderly woman on Kittyhawk drove into the side of the truck and was killed. The tractor trailer left 90 feet of skid marks.

“The Auburn police were ready to arrest him for failure to stop and speed,” McAllister said.

The truck driver told him he had stopped at the stop sign and could not see the woman’s car coming.

“He said he was going up through the gears and had reached about 15 miles per hour when he felt a bump and pulled the trolley brake, which controls the rear brakes.”

McAllister had an officer sit in the passenger seat of the truck and told the driver to do everything exactly as he said as fast as he could.

“He left skid marks 90 feet long every time,” he said, adding that he was also able to prove that the car was not visible to the truck driver when he entered the intersection.

“When you go to a scene, you have to be open minded and as impartial as possible,” McAllister said. “In many cases the operators who are initially thought to be the offender are not.”

Reconstructionists rely on witness statements for information, but they serve more to verify what the evidence at a scene shows.

Another source of information is the crash data retrieval unit that can be extracted from the airbags of most modern cars and trucks. GM makes the most informative model to date, McAllister said.

“It gives us 5 seconds of pre-crash data – speed, engine RPMs, throttle position and the brake switch on/off status, which tells us if the brake pedal was activated,” he said.

“It’s helpful in a lot of ways to make sure we’re accurate,” McAllister said of the unit. “It’s sort of a check-and-balance system. We won’t give (a reconstructionist) the data until they are done the reconstruction so we can’t be accused of manipulating the data.”

“Crash reconstruction is one of the most labor-intensive (law enforcement-related) specialties in the state,” he added. “You have your time at the scene and then you do research and then you do your report. The average report can take 14 hours, and sometimes you put in 60, 70 or 80 hours. It depends on the crash.”

Reconstructionists complete six weeks of training, which is split up into three sections with an hours-long test at the end of each section. They then have to do at least four reconstructions per year and have ongoing training to maintain their certification.