Traffic Light Rules
First identify the indication that governs your movement. Color matters, but so do whether the light is steady or flashing and whether it is a circle or an arrow. Compare three pairs: steady red with flashing red, flashing red with flashing yellow, and a flashing yellow turn arrow with a protected turn indication. These static diagrams explain recognition, not the timing of a particular intersection. The right-pointing arrow is an example; actual direction and local turn restrictions must be read at the road.
Steady circular red
Stop for the red indication. Whether a particular turn is allowed after stopping depends on the applicable rule and posted controls. Do not turn a national recognition diagram into a blanket permission for every red-light turn.
Steady circular yellow
The green indication is ending. Prepare to stop when it can be done safely; do not treat yellow as an invitation to race into the intersection. Continue to account for vehicles and people in the actual travel path.
Steady circular green
A green indication permits the movement it governs, subject to the applicable rules and other road users. It is not a promise that the intersection or the space beyond it is clear. Check before entering and yield as required.
Flashing circular red
A flashing red indication requires a stop, followed by proceeding only under the applicable yielding rules when safe. Distinguish it from a flashing yellow warning rather than assuming that every flashing light has the same instruction.
Flashing circular yellow
A flashing yellow indication warns you to proceed with caution. It is not the same stop instruction as flashing red. Look at the actual conflict and traffic conditions instead of reading flashing operation as a universal right-of-way grant.
Flashing yellow arrow
The arrow identifies a turning movement. A flashing yellow arrow permits that turn after yielding to conflicting traffic and pedestrians; it is not a protected green arrow. Read the actual arrow direction rather than applying the diagram to another movement.
Do not mistake a warning picture for a live light
The yellow SIGNAL AHEAD diamond contains red, yellow and green circles at the same time because it is a printed symbol. It warns of an upcoming signal; it cannot tell you the indication that will be displayed when you arrive. Look ahead for the actual signal and the back of any queue, then respond to that real control. A stopped vehicle may be closer than the signal itself.
Read the movement and the complete installation
A circular light and an arrow can govern different movements. Lane-use indications above a lane are another system and must not be confused with the intersection diagrams here. Posted turn restrictions, pedestrian indications and the position of the signal help identify which instruction applies. If an intersection has an unusual or unmodelled arrangement, use the applicable published handbook rather than inventing a rule from the nearest-looking diagram.