C.R.S. § 42-4-601: Department to sign highways, where.

(1) The department of transportation shall place and maintain such traffic control devices, conforming to its manual and specifications, upon state highways as it deems necessary to indicate and to carry out the provisions of this article or to regulate, warn, or guide traffic.

(2) No local authority shall place or maintain any traffic control device upon any highway under the jurisdiction of the department of transportation except by the latter's permission.