Turning movements and required signals
(1)No person shall turn a vehicle at an intersection unless the vehicle is in proper position upon the roadway as required in section 42-4-901, or turn a vehicle to enter a private road or driveway, or otherwise turn a vehicle from a direct course or move right or left upon a roadway unless and until such movement can be made with reasonable safety and then only after giving an appropriate signal in the manner provided in sections 42-4-608 and 42-4-609.
(2)A signal of intention to turn right or left shall be given continuously during not less than the last one hundred feet traveled by the vehicle before turning in urban or metropolitan areas and shall be given continuously for at least two hundred feet on all four-lane highways and other highways where the prima facie or posted speed limit is more than forty miles per hour. Such signals shall be given regardless of existing weather conditions.
(3)No person shall stop or suddenly decrease the speed of a vehicle without first giving an appropriate signal in the manner provided in sections 42-4-608 and 42-4-609 to the driver of any vehicle immediately to the rear when there is opportunity to give such signal.
(4)The signals provided for in section 42-4-608 (2) shall be used to indicate an intention to turn, change lanes, or start from a parked position and shall not be flashed on one side only on a parked or disabled vehicle or flashed as a courtesy or “do pass” signal to operators of other vehicles approaching from the rear.
(5)Any person who violates any provision of this section commits a class A traffic infraction.
Section 42-4-903 — Turning movements and required signals,
https://leg.colorado.gov/sites/default/files/images/olls/crs2023-title-42.pdf (accessed Oct. 20, 2023).