The Missouri Department of Transportation signs along the interstate warned drivers that traffic ahead was slow. But the truck rolled past those warnings, just as it rolled past the state trooper parked alongside the highway with his emergency lights on and holding a sign urging drivers to slow down. Vehicles on the highway were indeed slowing and stopping – all but the big rig thundering along Interstate 70 near Columbia.

The tractor-trailer was moving at 57 mph when it hit the first stopped vehicle. It crashed into two more in the horrific November truck accident that killed four people, including the 63-year-old trucker.

The Missouri State Highway Patrol says crash investigators have been unable to determine why the trucker never slowed or tried to avoid colliding with the stopped traffic.

“For an unknown reason, (the truck driver) failed to react to slowing and stopped traffic on westbound Interstate 70,” an investigator wrote.

A witness said the truck driver “never even hit the brakes and slammed right into those little cars just sitting there.”

The 18-wheeler hit the back of a Buick sedan first, and then slammed into a Ford sedan, crushing the small car between itself and another tractor-trailer. That last collision stopped the runaway rig from doing more damage.

Two sisters, 63 and 60 years old, were killed in the crash, as was a 44-year-old Columbia woman.

Investigators concluded that the trucker was not impaired at the time of the fatal wreck, but could not determine if he was distracted.

We might never know why this tragedy took place, but we do know that distracted drivers are a growing threat on our streets and highways.

If you or a loved one has been injured in a truck accident, speak to an attorney experienced in personal injury and wrongful death litigation before you speak to an insurance company representative.