La. Roads, Bridges and Ferries § 48:220.1
Whenever the department of highways, under its statutory authority takes over an existing road from a parish or municipality, unless there is an agreement between the two agencies to the contrary, the department shall acquire all of the rights which the ceding agency possessed with regard to the ceded road or street. In those instances where the highway was constructed by the parish or municipality without a recorded conveyance or dedication of the right of way by the landowner, and in those instances where the department has constructed a highway without a recorded conveyance or dedication by the landowner, the width of the right of way servitude for the said highway shall include the roadway, shoulder, roadside ditch and an area extending one and one-half feet beyond the rear or outside slope of the roadside ditch. Nothing herein shall affect title to any buildings or fences, nor require their removal without payment of just compensation therefor, nor shall anything herein affect title to the soil beneath the highway right of way nor to any minerals thereunder. The existence of the highways for a period in excess of three years shall vest title to the right of way servitude in the Department of Highways.
La. Roads, Bridges and Ferries § 48:220.1