SPANISH FORK — A snowplow clearing snow in Spanish Fork Canyon was pushed off the road by a passing semitrailer and rolled down a steep embankment Thursday, investigators say.

The dramatic crash was caught on video and prompted Utah Department of Transportation officials Friday to warn drivers to stay behind snowplows.

Terry Jacobson, a 23-year veteran of UDOT's snow removal services, was westbound on U.S. 6 when a semitrailer attempted to pass his snowplow on the right. Investigators say the semitrailer caught the wing of the plow and forced it off the road, pushing it across oncoming traffic and through the guardrail before it went rolling down a 300-foot embankment.

The safety features of the plow kept Jacobson alive, but the passenger side of his vehicle was destroyed, said UDOT Executive Director Carlos Braceras. Utah Highway Patrol troopers were able to quickly respond, and a number of motorists stopped to help extricate Jacobson from the crash, he said. The driver of the semitrailer stopped immediately and cooperated with the UHP.

"The safest place to be is behind these trucks at all times," Braceras said. "A good rule of thumb is about a football field of distance."

Had the semitrailer not attempted to pass, this collision would have been avoided, he said.

Braceras stressed the intensive schedule and dedicated work of the snow removal crews, who often work seven days a week, day and night. He emphasized the importance of safety and the impact that such an accident often has throughout the transportation department.

"Members of Terry's crew would have been here, but they are out repairing the guardrail as we speak," he said Friday.

Much of the details of the accident were caught on a dashcam by truck driver Lemalie Laulu.

"What makes me want to have a dashcam is because whatever I say, it's always going to be the truck driver's fault if … someone tries to cut me off," he said.

That's why he was rolling video on his drive along U.S. 6 just before noon Thursday.

"It was a bad road. It was slippery. The snow was coming down. I was driving up Price Canyon and I figured, 'You know what? I'm going to turn my dash cam on. You never know.'"

Laulu was just east of the Diamond Fork turnoff when the snowplow going the opposite direction crossed over his lanes of traffic and went over the side of the highway.

"Next thing I knew the plow truck was going down the cliff," he said.

It rolled several times, and Laulu said he immediately stopped to see how he could help.

"All I could see was the front axle of the truck, the plow hanging on a tree, and I couldn't see the truck. It was going further down the cliff," he said.

Jacobson is still recovering from the incident. Lundell noted that he is heavily bruised and sore and may have a concussion, but he is expected to recover.

Thursday's collision was the fourth involving a UDOT snowplow since the year started, but Braceras said this was the most severe.

Laulu knows there could have easily been a different outcome.

"I saw the plow truck just right in front of us. If I was a few seconds earlier, I would have been his cushion going down that cliff," he said.

Neil Lundell, UDOT's Region 3 supervisor, said the video reminded him of similar crashes he experienced when he drove a snowplow.

"All of our drivers know this, it's not a matter of if you're going to get in an accident, it's a matter of when," Lundell said.

Laulu echoed the warnings from UDOT officials, cautioning drivers to have patience.

"I want people to realize in this type of weather, any kind of weather, just slow down and let the people who are trying to help us drive safely and do their job," he said.

Contributing: Sean Moody