C.R.S. § 42-4-1014
42-4-1014. No commercial vehicles in the left lane - penalty
42-4-1014. No commercial vehicles in the left lane - penalty. (1) A driver of a commercial vehicle may not enter the furthest left lane when driving in the following areas unless specifically required or authorized to pass by law:
(a) Between milepost 115.5 and milepost 131.0 (Glenwood canyon);
(b) Between milepost 169.5 and milepost 173.0 (Dowd junction);
(c) Between milepost 180.0 and milepost 190.5 (Vail pass);
(d) Between milepost 205.5 and 221.0 (Eisenhower-Johnson tunnel);
(e) Between milepost 224.0 and milepost 228.5 (Georgetown hill); and
(f) Between milepost 243.0 and milepost 247.0 (Floyd hill).
(2) Any person who violates subsection (1) of this section commits a class A traffic infraction.