Colo. Rev. Stat. § 40-24-107
Whenever any person, company, corporation, or association obtains a franchise and right-of-way to operate an electric railroad over or along any county road in any county in this state and fails, refuses, or neglects, for a period of six months after the granting of any such franchise, to commence the work of constructing such electric railroad and in good faith to continuously prosecute the construction thereof to a final completion or fails, refuses, or neglects to operate or maintain said railroad in good condition and in good faith, for a period of one year at any one time after the granting of said franchise or right-of-way, such person, company, corporation, or association or its assigns shall forfeit all its right, title, and interest in and to such franchise and right-of-way, and the same shall become null and void; and it shall be the duty of the board of county commissioners of the county granting such franchise and the district attorney of the judicial district in which the county is situated to immediately institute the proper legal proceedings to cancel said franchise and all right, title, and interest of said person, company, corporation, or association or its assigns to use or occupy any portion of said county road.
C.R.S. § 40-24-107
For the penalty for failure of railroad company to commence construction, see § 40-20-105.