The Wreckage Speaks” is a three-part series on Tripping examining how officers with the Montgomery County Police Department’s Crash Reconstruction Unit investigate — an in essence re-create — major traffic accidents. 


The Montgomery County Police Department’s Collision Reconstruction Unit tells the story that victims in fatal crashes sometimes can’t. This Honda was involved in two-car head-on collision that fatally injured a woman riding in the back seat. (Fredrick Kunkle/The Washington Post)

As crashes go, this one didn’t look so bad.

Two cars — a Honda Accord and a Ford Mustang — had collided head on in the middle of a suburban road.

But someone had died in the wreckage, and that’s why I was there.

The Mustang had been traveling east, and the Honda had been going in the opposite direction, when they collided somewhere near the double-yellow line. The Montgomery County Police Department’s Collision Reconstruction Unit (CRU) had closed the two-lane road in Olney, a tree-lined bend of Bowie Mill Road near Fraley Farm Road about 31 miles north of Washington, to conduct their investigation.

The Mustang seemed barely damaged, its paint — a color called “competition orange,” I would later learn — cleaned and buffed to a luminous shine. It had a decal with an obscene phrase on the front bumper’s lower panel and an in-your-face vanity plate. The impact had spun the car and pushed it off the road into the entrance of a new housing development.


The Montgomery County Police Department’s Collision Reconstruction Unit is summoned any time there is a fatal crash or a crash with life-threatening injuries. “We’re the voice of the victim,” said Detective Cpl. David Cohen, who has been a member of the team for seven years. Here, Cohen peers inside a Mustang involved in a fatal head-on collision on Bowie Mill Road near Fraley Farm road on July 16, 2017. The driver of the Mustang survived, but one of the back-seat passengers of the other car was fatally injured. (Fredrick Kunkle/The Washington Post)

The blue Accord looked worse. The engine compartment had been stove in, and the windshield showed a spider web of cracked glass. But the passenger compartment was intact; on the face of it, the damage didn’t seem to fit with what I expected to see in a fatal crash. A blinker was going on and off, as was the door chime.

I was allowed this close to the crash scene because Capt. Thomas Didone, head of the county’s traffic division, had invited me to join the crash reconstruction team as part of a behind-the-scenes look at what they do.

I had become interested in the science of crash reconstruction after a fatal motorcycle crash last April on Connecticut Avenue. The motorcyclist — a 24-year-old Arlington man — was killed when a GMC Yukon made a left turn in front of him at Thornapple Street, in a neighborhood of single-family homes near East-West Highway in Chevy Chase.

This crash had special resonance for me because I own a motorcycle — a Triumph, too, the same brand as the victim’s — and I often drive the same route the victim took. The site was also not far from the place where a distracted driver had drifted close to my motorcycle one day, which I had written about.

When I called police headquarters to find out about the crash investigation, Didone suggested I see how the crash reconstruction team works from beginning to end.

My chance came a few weeks later when I received a text from Detective Sgt. John P. O’Brien, a 12-year veteran of the department who joined the CRU in April 2017. O’Brien, who is the team’s deputy commander, met me at the scene and led me past the yellow police tape strung across Bowie Mill Road.

It was a pleasant if breezy Sunday morning in July, with cicadas buzzing as the police went about their business over the sprawling crash site. The team always shuts down the entire road around a crash they’re investigating so as not to miss evidence.

I walked up cautiously, not sure whether I was about to see something horrible and not wanting to do anything that might compromise the police investigation.

Seven team members, wearing bright green safety vests over their police uniforms, were photographing evidence, logging data and taking measurements. They used spray paint to mark points where the undercarriage of a vehicle had gouged the pavement or where debris lay.

Four other CRU members were working the crash off-site. Some had been sent to local hospitals to obtain statements from survivors. By the time I arrived, the work was winding down, and tow trucks were waiting to haul the wreckage away.

O’Brien introduced me to Detective Cpl. David Cohen, who was standing near ribbons of black fluid leaking from the damaged vehicles.


Detective Cpl. David Cohen at the site of a fatal crash in Montgomery County. (Fredrick Kunkle/The Washington Post)

Cohen filled me in on what the team knew. Three people had been riding in the Honda, including a  woman and a child who had been in the back seat. The woman had been killed, and her body had been taken to Baltimore for an autopsy. The Mustang’s driver had been alone in the vehicle. Much of what they knew beyond that was preliminary, however, and some of what they knew they could not share until the case has been closed.

Cohen, who has been on the team more than seven years, had seen many bad crashes, and several that were horrific, including a Valentine’s Day wreck that took the life of a young woman and sent her boyfriend to prison. His experience, including 15 years as a volunteer firefighter, affected his thinking about highway safety: On another occasion, Cohen talked of wanting a motorcycle — a cruiser, not a racing bike — but he said he wouldn’t drive one around Washington. The work affected his sense of humor, too: It ran toward the gallows variety common among first responders, including his wife, who is a maternity ward nurse.

“We kind of joke that she sees people on the first day of life and I see them on their last day,” Cohen said. “We have a sick sense of humor around here, but that’s how we cope.”

If life can seem at times like a revolving door, it’s also because the steady number of crashes keeps them busy. The team is summoned to a crash scene about 30 to 40 times a year, anytime there’s a fatal crash or a crash with life-threatening injuries. Although a lead investigator — determined by rotation — oversees each investigation, the CRU works as a team from the moment they get called out to the conclusion of the case. After determining who’s at fault, the team also helps to decide whether criminal charges should be filed.

Their work includes obtaining eyewitness statements; reviewing footage from mounted security cameras if available, including ATMs; and analyzing data stored in a vehicle’s Event Data Recorder, more commonly known as the black box. Their research takes them into the minutiae of automobile design and road construction, and into the complexities of mathematical formulas that describe the physics of a crash.

As the CRU members are fond of saying, they use Newtonian physics to piece together a narrative from the violent chaos of a fatal crash. It’s a story that the victims, and sometimes survivors, cannot tell for themselves.

“We’re the voice of the victim,” said Cohen, who is one of eight full-time members on the team. In addition, the team relies on assistance from a number of decentralized members on the police force who undergo training in crash reconstruction and assist at the site of a crash.

Officer Jacob A. Burley had been a member of the decentralized team for about three years before joining the centralized unit. The crash on Bowie Mill Road would be his first as lead investigator.

Burley and others were taking measurements of the crash, using what they called “The Pole,” a high-tech instrument similar to a surveyor’s tool. Known as a “total station,” the device uses GPS, laser technology and electronic measuring technology to create a 3-D map of the crash site.

Their point of reference was a penny driven into the pavement near the wreckage, which would still be there if the team needed to return weeks later.


Officers from the CRU drag the “sled” across the pavement at the site of a fatal crash. The device measures friction on the roadway service. The data can help the team reconstruct what happened in a fatal crash. (Fredrick Kunkle/The Washington Post)

Other officers were dragging a device over the pavement called a “sled,” which analyzes the degree of friction on the roadway surface. Along with skid marks and other data, the information helps to determine a vehicle’s speed.

In this crash, however, there were no skid marks, which suggested that the two cars had collided with little warning when one or both crossed the centerline. Cohen noted that sometimes there are no skid marks because anti-locking technology is designed to slow the vehicle without locking up the wheels, even when someone slams on the brakes.

Next we took a look at the gouge marks. As Cohen explained, when two vehicles collide, the energy of their collision has to go somewhere, and often that’s downward, pushing the undercarriage into the road. The gouge marks were on the Mustang’s side of the road — which offered another clue as to what happened, as I would later learn.


Detective Cpl. David Cohen examines the air bags that deployed in a Mustang involved in a fatal head-on collision on Bowie Mill Road near Fraley Farm Road. The driver of the Mustang survived, but one of the back-seat passengers of the other car was fatally injured. (Fredrick Kunkle/The Washington Post)

Next we examined the passenger restraints and safety devices. An array of air bags had deployed in each vehicle, including curtain air bags that protect an occupant from hitting the windows. But as Cohen explained, these are only effective if the passengers are wearing seat belts. And determining whether they were in use is important to understanding how a person died.

Survivors can say whether they belted, but there are also other ways to tell, such as from bruising and fabric marks on a person’s body. Police can also corroborate seat belt use by examining the belts themselves.

Seat belts in newer vehicles come with devices known as pre-tensioners that detect the rapid deceleration of a crash and then ignite a small explosive charge that instantaneously coils up slack from the belt before impact. This restrains the occupant’s body in the proper position for air bags to be most effective in protecting the passenger from impact.

The Mustang had been equipped with the sort of heavy-duty seat belt often found in racecars. Cohen could tell, just by looking at it, that the Mustang’s driver had been wearing his seat belt.

For reasons I would understand later, we didn’t examine the seat belts in the Honda when we peered in the back seat.

Cohen asked me what my theory was.

“Just from the looks of it, it almost suggests it was the blue car that was over the line,” I said. “Looking at the damage of this car — it’s bad; it’s head on — but I’m going to guess that the people in the back seat of the car didn’t have their seat belts on.”

Cohen couldn’t comment at the time. He said it would probably take at least six weeks before the team had a definitive answer.

And with that, the tow trucks started hoisting the wreckage onto a flatbed for the trip to the county’s impound lot.

NEXT:  THE IMPOUND LOT