(a) An owner of real property that fronts along a road that has a building or set-back line established under this subchapter is charged with notice of the building or set-back line order.
(b) The commissioners court shall show in a general manner each building or set-back line established under this subchapter on a map. The map shall be filed with the county clerk.

(c) If the county does not begin the construction of the improvement or widening of a road along which a building or set-back line has been established within four years after the date the building or set-back line is established, the building or set-back line becomes void, unless the county and the affected property owners agree to extend the time period for the improvements or widening.