Whenever, in the discretion of the state highway commissioner, it is necessary to acquire the property or rights of way, or any part of or interest in said property or rights of way, owned by a railroad, railway or public utility having the right of eminent domain, in order to establish, construct, widen, straighten, alter, relocate or otherwise improve a trunk line highway, the state highway commissioner shall be authorized to enter into negotiations with such railroad, railway or public utility for the purchase of said property, rights of way, or any part thereof or interest therein, and to enter into an agreement with any such railroad, railway or public utility to exchange other designated property or interests in property for such property, rights of way, or any part thereof or interests therein, whenever such other designated property or interests in property shall be acquired by him; and whenever any such agreement has been entered into, the said state highway commissioner shall be authorized and he is hereby empowered to acquire such other property or interests in property by purchase or condemnation, and when acquired to execute the necessary conveyances and releases thereof to such railroad, railway or public utility for its use, and to take in exchange therefor the railroad, railway or public utility property, rights of way or any part thereof or interests therein for such public highway purposes in accordance with such agreement.