A Greene County man who the THP says ran into the side of a tractor-trailer on Interstate 81 late Saturday was listed in critical condition this morning at the Johnson City Medical Center.

Trooper Ronnie McClure said he was dispatched to the 42-mile marker of Interstate 81 in northern Greene County at 10:59 p.m. Saturday after the THP received a report that a pedestrian had been struck by a tractor-trailer.

On arrival, Trooper McClure, who normally is assigned to Washington County, was told by witnesses that Jeffrey A. Cox, 44, whose address he has been unable to confirm, had run from the right shoulder of the southbound traffic lanes into the side of a southbound tractor-trailer.

Trooper McClure said this morning that he had been unable to speak with Cox, who was listed in critical condition in the intensive care unit at the Johnson City Medical Center.

"The accident is still under investigation," Trooper McClure said this morning.

Truck driver Jeffrey Howard, of Rutledge in Grainger County, told the THP that he saw Cox on the shoulder of the highway and changed from the right lane to left lane to move away from him.

But Cox, according to witnesses, ran from the shoulder of the road into the passenger side of the truck's cab.

Trooper McClure said officers did not find a car parked in the area of the accident and had been unable to learn how Cox got onto I-81.

After being treated at the scene by Greene County-Greeneville Emergency Medical Services (EMS) personnel, Cox was flown to the Johnson City Medical Center by a Wings Air Rescue helicopter.

Units of the Baileyton-based United Volunteer Fire Department had established a landing zone in the southbound traffic lanes of I-81 to enable the helicopter to land.