Until the two travel ways are made as required by § 45.2-726, no more than 20 miners shall work underground in the mine at one time. No additional development shall be permitted until the connection is made to the second opening. In a mine in which final pillar removal operations necessitate closing the second opening, no more than 20 miners shall be permitted to work in the mine.
Number of miners in openings
Va. Code Ann. § 45.2-728, under Chapter 7. Requirements Applicable to Underground Coal Mines; Mine Construction..
Va. Code Ann. § 45.2-728