Identifying Traffic Signals by Color
What kind of world would we live in without traffic signals? With a U.S. population of about 325 million, it’s no wonder why big cities (and most towns for that matter) have traffic signals to control the flow of traffic. You can find traffic signals along the side of the road and more commonly, above road intersections. Traffic signals can vary in style depending where in the U.S. you are, but all are now automated and operate similarly—to control the flow of traffic for drivers and pedestrians.
What Does Each Color in a Traffic Signal Mean?
Red Traffic Signal:
A red traffic light means stop. When approaching a red light at an intersection, the driver should come to a complete stop at the marked stop line. If there is not a marked stop line, the driver should stop before entering the crosswalk. If there is no crosswalk, the driver should stop before entering the intersection.
Note: Turning Right or Left on Red
If there no sign posted designating otherwise, you may make a right turn at a red light. You also may make a left turn at a red light when turning from a one-way street onto another one-way street that has traffic moving to the left. In both instances, drivers must come to a complete stop behind the stop line and yield the right-of-way to pedestrians and cross-traffic before turning.
Yellow Traffic Signal:
The yellow light warns that the signal is changing from green to red. When the red light appears, you may not enter the intersection.
Green Traffic Signal:
Yes, green means go, but go after yielding the right-of-way to any pedestrians and vehicles in the intersection or crosswalk.
Flashing Red Traffic Signal:
Stop, yield the right-of-way to traffic within the intersection or crosswalk and proceed when safe. This sign is used at intersections when a stop sign alone is hard to see or where additional emphasis on the stop sign is needed. Flashing red traffic signals are also used at railroad crossings to warn of approaching trains.
Flashing Yellow Traffic Signal:
A flashing yellow traffic signal at an intersection means to proceed with caution.
Traffic Signal with a Green Arrow:
When the green arrow is pointed upward the driver may go straight ahead only. When the green arrow is pointed to the right the driver may turn to the right. When the green arrow is pointed to the left the driver may turn to the left. The driver does not need to stop if they are traveling in the direction of the arrow.
Traffic Signal with a Red Arrow:
A red arrow means do not make the movement shown by the arrow until a green arrow appears.
Flashing Red Arrow Traffic Signal:
A flashing red arrow should be treated as a ‘stop sign’. You may proceed once you stop and determine the intersection is clear of all pedestrians, vehicles, and other potential hazards.
How Many Colors are in a Traffic Signal?
Three: red, green, and yellow, but the overall design has changed over the years. Most notably all traffic signals these days are automated electric signals. The world’s first electric traffic signal was installed “on the corner of Euclid Avenue and East 105th Street in Cleveland, Ohio” in 1914. The colors are believed to have derived from early train signals from the 19th century.
What Should You Do If All Traffic Signal Lights Are Out?
A blacked-out traffic signal works the same as a four-way stop intersection. If you pull into an intersection and all traffic lights are out, you must stop at the intersection and then proceed when you know other turning and approaching vehicles, bicycles, or pedestrians have stopped.
Not sure who goes first? Review our 4-way stop rules.
Find your state’s driver handbook online and refresh your memory about signs and signals or consider taking an online refresher driving course to stay current with best driving practices.
Frequently asked questions
What do the three main traffic signal colors mean?
Red means stop, yellow means the signal is changing from green to red, and green means you may proceed after yielding to any pedestrians or vehicles still in the intersection. At a red light, come to a complete stop at the marked stop line, or before the crosswalk if there's no line, or before entering the intersection if there's no crosswalk. At yellow, you cannot legally enter the intersection once the red appears. At green, look before you go, since cross traffic clearing the intersection has the right of way.
When can I make a right or left turn on a red light?
Unless a sign specifically prohibits it, you may turn right at a red light after coming to a complete stop and yielding to pedestrians and cross traffic. You may also turn left on red, but only when turning from a one-way street onto another one-way street where traffic moves to the left. In both cases, the complete stop behind the stop line is required, not optional, and pedestrians and cross traffic always have the right of way. Watch for posted No Turn on Red signs at busy intersections.
What should I do at a flashing red traffic signal?
Treat a flashing red signal exactly like a stop sign. Come to a complete stop, yield the right of way to any traffic or pedestrians already in or approaching the intersection, and proceed only when it's safe. Flashing reds are used at intersections where a regular stop sign would be hard to see or needs extra emphasis. You'll also see them at railroad crossings to warn of an approaching train, in which case you must stop and wait until the lights go dark and the gates fully rise.
What does a flashing yellow signal mean?
A flashing yellow signal means proceed with caution. You don't have to stop, but slow down, scan the intersection for cross traffic, pedestrians, and cyclists, and be ready to yield. Flashing yellows are common at low-volume intersections overnight and at school zones outside school hours. Flashing yellow arrows in turn lanes mean you may turn after yielding to oncoming traffic and pedestrians, but the green arrow still has the right of way when it appears.
What's the difference between a green arrow and a solid green light?
A green arrow gives you a protected movement in the direction the arrow points: straight, right, or left. Oncoming traffic and conflicting pedestrians are held at red, so you can proceed without yielding. A solid green light, on the other hand, gives you permission to proceed but you must still yield to pedestrians in the crosswalk and to oncoming vehicles when turning left. A red arrow means do not make the movement shown until a green arrow appears, even if the rest of the signal is green.
What do I do if all the lights at an intersection are out?
A blacked-out signal works the same as a four-way stop. Come to a complete stop at the intersection, then proceed only when you've confirmed that other turning and approaching vehicles, bicycles, and pedestrians have stopped or yielded to you. First to arrive goes first, and when in doubt, yield to the vehicle on your right. Drive especially carefully through these intersections; power outages catch other drivers off guard and assumptions about right-of-way cause crashes.
