The driver, who was believed to be from Finleyville and in his late teens or early 20s, was evacuated by medical helicopter to a Pittsburgh hospital for treatment of a severe gash on his forehead and for possible back injuries.
The crash happened at 6:20 p.m. at Coal Bluff Road and Route 837 south of Elrama in Union Township.
According to Nick DiLicia, owner of DiLicia Stone Co. of Finleyville, the car struck the billboard and then the rear wall of his concrete block garage, knocking a 4,000-pound Bobcat construction vehicle eight feet across the garage.
DiLicia said the car, believed to be a sedan, smashed some construction stone and stone-cutting tools in his building.
He estimated the damage at between $50,000 and $70,000.
“That car had to be going fast when it skidded on the gravel,” DiLicia said Tuesday evening.
“That road, Coal Bluff Road, had been paved with new gravel just Monday,” he added.
State police in Belle Vernon investigated the crash.