(a) The commissioners court may not make an assessment against abutting property or the owners of the property in excess of the special benefit to the property and its owner in enhanced value caused by an improvement ordered under Section 286.002(a).
(b) A railroad right-of-way does not benefit from an improvement described by Section 286.002(a), and the commissioners court may not assess the cost of the improvement against a railroad right-of-way.