La. Roads, Bridges and Ferries § 48:303
For the purposes of this Part, the highway authorities may acquire private or public property and property rights for controlled-access facilities and service roads, including rights of access, air, view, and light, by donation, purchase, exchange, lease, or expropriation in the same manner as they are now or hereafter may be authorized by law to acquire property or property rights in connection with highways and streets within their respective jurisdictions. They may acquire any use of the property or the full ownership of it.
In connection with the acquisition of property or property rights for any controlled-access facility or portion thereof, or service road in connection therewith, the highway authorities may, in their discretion, acquire an entire lot, block, or tract of land when they determine it will best serve the interests of the public, even though said entire lot, block or tract is not immediately needed for the right of way proper.
La. Roads, Bridges and Ferries § 48:303