Bair, who was in a Bair's Pools work vehicle, was crossing the tracks after dropping off a load of fill, according to Keith Martin, who works at Martin's Elevator grain mill.
"I was in the building and heard a crash," said Martin. He said he ran outside and found Bair had been thrown from the vehicle.
"He's lucky to be alive," Martin said.
Martin said Bair was conscious but lying down when he reached him.
Bair was taken to Washington County Hospital where he was listed in serious condition Thursday evening, a nursing supervisor said.
The left front panel of the truck was mangled and the ends of the yellow snow plow were crushed together.
Trash from the truck littered the muddy ground and small puddles of antifreeze formed from a leak in the vehicle.
The train sat idling more than 600 yards away as police investigated the accident. A Norfolk Southern employee at the scene refused to comment.
Norfolk Southern police officers would conduct their own an investigation, deputies said.
The train involved in the accident was considered "a local," which makes regular trips between Hagerstown to Shippensburg, Pa., said Norfolk Southern spokeswoman Susan Bland.
The train, which was hauling paper and food products in eight cars, was en route to Shippensburg at the time of the accident, Bland said.
Those operating the train were not injured and the train had minimal damage, she said.
She said it was not known how fast the 900-ton train was moving when it hit the truck. The area is posted for 40 mph, she said.
Martin's Elevator relies on train transportation to ship a lot of its grain, said Martin. He said trains go past the mill 15 to 20 times a day.
The area where the accident occurred is on a slight incline and the tracks curve around the mill. There are no warning signs or lights at that spot.