Section 9(6) in The Calcutta Metro Railway General Rules, 2000
(6)At the close of the work, the Engineering official-incharge shall issue a certificate in writing to the nearest Station Master that the material trolley/lorry has been taken off the line and secured, the line is free from all obstructions, third rail alignment is clear from any tools, implements, wire etc. which might have been used at site, no staff is working in the section and the track is safe for resumption of train services. On confirmation of the receipt of safety certificate by the Station Master, the traffic controller shall permit switching 'on' of traction current and resumption of train services.
