New York Consolidated Laws, Labor Law - LAB § 411. Ingress and egress

The commissioner shall require that a mine operating through either a vertical or inclined shaft, or a horizontal tunnel, shall have not less than two adequate and accessible outlets, at least one hundred and fifty feet apart, as a condition precedent to employment of any person in the mine.  The subterranean workings shall connect such outlets with each other.  They shall at all times provide safe and separate passage between the subterranean workings and the surface.