The Railway Companies (Emergency Provisions) Act,1951
Section 18. Power of Central Government to acquire railway of railway company
(1) Where under any instrument, having effect by virtue of any law other than this Act or by virtue of an agreement arrived at between the parties, provision is made for the purchase by a person or local authority or the State Government of a railway which is the property of a railway company on payment of the value thereof calculated in the manner and subject to the conditions specified in the instrument, the Central Government shall also have the same right to purchase the railway on the same terms and subject to the same conditions as the person, local authority or the state Government has under the instrument.
(2) If in respect of any railway the Central Government exercise its right of purchase under this section, any person, local authority or State Government in whom or in which a similar right is vested under the instrument, shall be deemed to have become disentitled to exercise the same.