The Company shall as regards the underground railways from time to time submit for the approval of the Secretary of State plans, sections and other details of their proposals with respect to—
(a)permanent-way, tunnels, platforms, stairs, lifts, escalators and other communications;
(b)rolling stock;
(c)lighting;
(d)signalling; and
(e)ventilation;
and any rolling stock and work included in the said proposals shall be constructed and maintained only in accordance with plans, sections and other details as approved by the Secretary of State.