Back-poling shall be prohibited except (i) at a place where the trolley pole cannot be reversed or (ii) when going up an extremely steep grade. In such circumstances, back-poling shall occur only at very slow speed.
Back-poling
Va. Code Ann. § 45.2-757, under Chapter 7. Requirements Applicable to Underground Coal Mines; Mine Construction..
Va. Code Ann. § 45.2-757