Traffic signals or signal devices shall conform strictly with the provisions of this article.
A three-color system shall be used; red, amber and green. Green means permission for traffic to go, subject to the safety of others or the specific directions of an officer, official sign or special signal. Red means traffic to stop before entering the intersection or crosswalk and remain standing until green is shown alone, unless otherwise specifically directed to go by an officer, official sign or special signal. Amber, or yellow, when shown alone following green means traffic to stop before entering the intersection or nearest crosswalk, unless when the amber appears the vehicle or street car is so close to the intersection that with suitable brakes it cannot be stopped in safety. A distance of fifty feet from the intersection is considered a safe stopping distance for a speed of twenty miles per hour, and vehicles and street cars if within that distance when the amber appears alone, and which cannot be stopped with safety, may proceed across the intersection or make a right or left turn unless the turning movement is specifically limited.
All other uses of green, red, amber or yellow lights so located as to be confused with traffic signals shall be discontinued.