C.R.S. § 42-4-2001

(1) Any person who operates a commercial motor vehicle solely in intrastate commerce for the purpose of transporting wet, ready-mix concrete need not comply with 49 CFR 395.3 (b). No such person shall drive for any period after: (a) Having been on duty seventy hours in any seven consecutive days if the employing motor carrier does not operate every day in the week; or (b) Having been on duty eighty hours in any period of eight consecutive days if the employing motor carrier operates motor vehicles every day of the week. (2) Within a seven-day workweek all hours of service after sixty hours are voluntary starting the next scheduled workday. (3) Twenty-four consecutive hours off duty shall constitute the end of any seven or eight consecutive-day period. (4) Any commercial motor vehicle that transports hazardous materials shall be exempt from this section and shall be subject to the federal hours-of-service limitations in 49 CFR 395 and 350.