On a cold January morning, a car moving south on Washington Road in the center lane failed to negotiate a curve after passing Mt. Lebanon Boulevard. The car crossed the double yellow line and sideswiped another car traveling in the opposite direction, then crashed head-on into a third car that was heading north in the left-hand lane, pushing it backwards into the right northbound lane, spun around and struck one final car that was also traveling north. There were some injuries; two were serious.

The whole event took less than a minute. The on-scene investigation took about five hours. And that was just the beginning.

The Mt. Lebanon Police Department’s traffic services unit handles fatal and serious crash investigations. Crashes, not accidents. We don’t call them accidents anymore. “An accident would be if a meteor fell from space and knocked off your side view mirror,” says Lt. Duane Fisher, the unit’s supervisor. “The vast majority of all crashes involve a failure of some kind, whether it’s with the vehicle, the roadway, the environment, or, most likely, the driver. Our job is to determine where the failure occurred.”

Once investigators determine the cause of the crash, the police department and the district attorney use the data to decide whether charges need to be filed. The information is also available for insurance companies’ purposes or other legal matters.  If the fault is in part because of the configuration or condition of the road, weather or visibility issues, the unit could make recommendations that ultimately would result in changes to the infrastructure, signage, speed regulations or other things to promote safer driving.

In 2014, the police department responded to 216 reportable crashes—crashes that either resulted in injuries or rendered a vehicle undriveable—103 non-reportable crashes, 96 hit-and-runs, 11 pedestrian-involved crashes, and 21 caused by drivers under the influence of drugs or alcohol. Of the 201 reportable crashes in 2013, 90 resulted in injuries. There was one fatality, a man who failed to negotiate a turn, drove off the road and hit a telephone pole in the 1300 block of Washington Road, not too far from the January 31 crash. Speed and driving under the influence (DUI) were both contributing factors to the fatal crash. Even though DUI arrests increased 35 percent in 2014 (118 arrests), DUI crashes also increased, from eight to 21.

As part of their initial training, all Mt. Lebanon police officers acquire a basic understanding of the mechanics of crash investigation. Traffic unit officers have more specialized training, beginning with the basics offered at the state police academy and moving onto more advanced concepts. Among the basics are photography, collecting physical evidence from the roadway and the involved vehicles, and the mathematics of mayhem: formulas to calculate minimum speed, critical curve speed and the skid resistance of a roadway surface, just to name a few.

A more advanced course, Technical Collision Investigation, includes a heavier dose of math and physics, teaching officers to calculate things such as the trajectory of a vehicle that leaves the ground, vehicle flips or vaults (otherwise known as rollovers), and mass and velocity calculations. Additional reconstruction courses feature more math and physics, expanding the focus beyond motor vehicles to crashes involving motorcycles, bicycles and pedestrians.

These advanced classes split officers into teams, one to set up a crash, one to investigate it. Setting up a crash might be something like putting a crash dummy on a bicycle and smashing into it with a car. At one point Fisher actually served as a test subject, suiting up in firefighter turnout gear and getting dragged along a stretch of pavement to measure and determine the coefficient of friction of a tumbling human body.

“That was a lot of fun,” he says.

Because of the MLPD’s policy of rotating officers in and out of the department’s specialized units, Fisher is one of four officers trained to reconstruct crashes, and several additional officers have more than just the police academy basics. Officer Jeff Bileck, who was recently rotated back to the patrol unit, is one of the trained reconstructionists. His replacement, Officer Cory Nolte, is taking classes and studying to be a crash investigator. Officer Mike Shell is also a member of the unit.

Reconstructing a crash is like piecing a puzzle together. Investigators start with the tires, analyzing skid marks and skip marks, which are common to cars with antilock brakes—the brakes apply, release, apply, release and the tire marks are dotted. They also look at yaw marks, caused when a vehicle turns suddenly at a higher speed, scuff marks, made by tires that are sliding while the wheel is turning, and several other sorts of marks that yield a more complete picture of what happened.

Other parts of the car also can provide information. If a headlight bulb filament is unbroken, it might mean the headlights were off at the time of the crash. If a driver is injured, the type of injury can help solve the puzzle.

“There really are three [types of] collisions,” Fisher says. “First is your car striking something, then you striking things inside your car, and finally the collisions inside your body as organs and tissues come into contact with each other.” All three of the collisions can help tell the story of the crash.

That’s what took up a big chunk of the traffic unit’s Saturday during the Washington Road crash in January.

“This is our one shot to get everything at its best,” Fisher says. The investigators interview witnesses, get photos of where the cars are in relation to fixed points on the landscape, also get pictures of the tires and the inside of the vehicle, sketch out where the cars are in reference to fixed points in the landscape, and check the undercarriage for damage or debris that may have accumulated during the collision.  Other factors can include damage to stationary objects like guide rails or telephone poles, damage to the road surface, and paint from other vehicles.
The investigation continues long after the scene is cleared. The investigators take the physical evidence and match it with the witness statements. Collision diagrams, once laboriously drawn by hand, now can be done much faster and more accurately on the computer. The department even has a software program that can take the crash diagrams and animate them.

It’s all part of a process that brings cold, hard logic to a chaotic scene. “In court, you might beat the traffic laws,” says Fisher. “But you can’t beat the laws of physics.”