A Utah Highway Patrol trooper is nursing his wounds Tuesday after his parked patrol car was rear-ended by a semitrailer truck pulling three trailers.

Sgt. Larry Wehrli was working I-15 traffic control at the time of the 12:20 a.m. accident. The 18-year UHP veteran suffered minor head injuries and was taken to LDS Hospital, where he was treated and released."He's doing fine now," Wehrli's son said Tuesday, adding his father was resting at home.

Investigators said Wehrli was sitting in his car during traffic-control duty along an I-15 construction site on the southbound lanes near 6800 South.

"He was helping protect road crews working on the highway," UHP Lt. Verdi White said.

A southbound semi truck pulling three trailers traveling on the outside right lane passed two other tractor-trailers to the left. When the passing truck moved back into the outside lane, he collided with Wehrli's parked car, White said.

"Sgt. Wehrli was actually able to call in the accident (to dispatch)," White said. "He remained conscious, but he had some pretty good cuts."

The unidentified driver of the truck was not injured.

The semi's three trailers rolled during the accident, closing a section of I-15 until 6 a.m. Tuesday.

The accident is being investigated by the Salt Lake County Sheriff's Office.

Because of I-15 reconstruction projects, trucks longer than 98 feet, including triple trailers, are restricted from traveling along the section of highway where Tuesday's accident occurred, according to Utah Division of Transportation officials.