(a) Every railroad company shall be required to build and maintain, at its own expense, good and sufficient cattle guards on each side of every public road or private way and on the dividing line of adjoining landowners, at such points where the railroad may cross such public roads, private ways, or dividing lines, when necessary to protect said lands.

(b) Thirty days' written notice to build such cattle guards shall be served on any agent or officer of the railroad company by the owner of the lands to be affected by such cattle guards. The notice shall be directed to the railroad company, shall contain a description of the point where such cattle guard is desired, and shall be signed by the landowner or his agent or attorney and attested by some officer under his official seal. A certified copy of the notice shall constitute prima-facie evidence of the contents of the original notice.