It is unlawful for any corporation or person to construct or use an ordinary railroad for the transportation of freight and passengers upon any county road or county highway of this state, without the consent of the county legislative body of the county in which the road lies. Before it is lawful for the county legislative body to give such consent, the corporation desiring to construct such railroad shall procure and file with the county legislative body the written consent of the owners of the lands abutting upon such road or highway, aggregating in such abutting length at least one-half (1/2) of all the lands in value, such value to be the value of the abutting lands running back from such road two hundred feet (200′) upon both sides of the road to be occupied by the railroad. Any ordinary railroad constructed upon such county road or highway, without the consent of the county legislative body first lawfully obtained, shall be considered a nuisance, and liable to be treated as such, both by the public authorities and by private persons. But when the consent of the county legislative body has been first lawfully obtained, such railroad may be lawfully constructed and operated upon such road or highway under such restrictions as to the manner of construction and mode of use as the county legislative body may see fit to impose in granting the license; provided, that railroads already constructed upon any road or highway of this state under a license of the county legislative body are declared to be lawfully constructed, and this section shall not be construed as requiring a new license from the county legislative body for such construction or operation under its provisions.