Nothing in sections 11 and 12 shall authorise--
         (a) a railway administration of the Government railway to do anything on or to any works, lands or buildings vested in, or in the possession of, a State Government without the consent of that Government; and
         (b) a railway administration of a non-Government railway to do anything on or to any works, lands or buildings vested in, or in the possession of, the Central Government or a State Government, without the consent of the Government concerned.