If the relocating, raising, rerouting, changing the grade, or altering the construction of a highway, railroad, electric transmission line, pipeline, or telephone or telegraph property is required by the authority's exercise of the power of eminent domain, power of relocation, or any other power, the required action shall be taken at the sole expense of the authority. "Sole expense" means the actual costs of the required action and of the provision of a comparable replacement that does not enhance the facility after deducting the net salvage value derived from the old facility.
Tex. Loc. Gov't. Code § 281.054