36 Pa. Stat. § 2422
In every case, when such machinery propelled by steam is being moved upon a public road or highway, it shall be the duty of the owner or owners, or persons in charge of such machinery, upon the approach, in either direction, of all persons traveling in vehicles or in charge of teams, to move such machinery as far as practicable to the right or left of the road to a position where the said approaching vehicle or team may pass with the greatest safety, and stop the same before such persons, traveling in vehicles or in charge of teams, shall have arrived within three hundred feet of such machinery, and the owner or owners, or persons in charge of such machinery, shall assist such passing vehicle or teams until they are safely by the danger; and if there be any obstruction to the view of the road it shall be the duty of the owner or owners, or persons in charge of such machinery, not to approach such obstruction nearer than three hundred feet without going to the place to see that the road is clear, or sending some competent person for the purpose.
36 P.S. § 2422