What Does Each Traffic Light Signal Mean? A Complete Guide

Red and green traffic lights have been around since the 1800s, when British traffic officers used to rotate gas lamps that burned red and green to control the movement of mostly horse-drawn vehicles. It’s safe to say just about everybody knows what the red and green lights mean. These days, of course, drivers also have to understand a number of other traffic light symbols to avoid collisions. Some light symbols flash, some display arrows, and some show colors other than red and green.

For example, the amber (yellow) light didn’t come along until 1920, and some drivers still aren’t sure what it means. And if you’re driving in Japan, you may see a blue light instead of a green one because the Japanese language doesn’t distinguish blue from green. Traffic light symbols vary from country to country, but they’re fairly uniform if you’re driving in North America. Here’s what they mean.

Solid Traffic Light Signals Explained

Red light

This is the most unambiguous of all traffic light symbols. A red light means “Stop” pretty much anywhere you go. When you approach an intersection with a red light, you must come to a complete stop and remain stopped until the light changes color.

Green light

A green light unambiguously means “Go.” If you’re approaching an intersection with a green light, you can proceed straight through at your current rate of speed. A green light doesn’t necessarily mean you can make a turn, though. More on that later.

Amber (yellow) light

An amber light means that a green light is about to turn red. You should stop if it is safe to do so; otherwise, continue through the intersection.

• NOTE: You can legally enter an intersection when the light is yellow, but drivers tend to interpret this rule differently. To paraphrase Miami Herald humor columnist Dave Barry, the interpretation in Florida seems to be that you can drive through a red light as long as you can remember when it was yellow. In most other states, though—and probably also in Florida—you’re risking a ticket unless you happen to have a very short-term memory.

Flashing Traffic Light Signals Explained

Flashing red light

When you approach an intersection with a flashing red light, you should treat the light as a stop sign. Come to a full stop, check traffic in all directions and proceed only if it is safe to do so. You’ll often see flashing red lights on rural highways, and you might also see them at major intersections when there is a power outage.

Flashing yellow light

A flashing amber or yellow light means to slow down and proceed with caution. It warns of an awkward traffic situation, such as an obstruction or a school crossing. You don’t necessarily have to stop, but if there’s any confusion about what’s going on around you, you should proceed very slowly.

Flashing yellow lights at a pedestrian crosswalk

When you see a series of bright flashing yellow lights at a pedestrian crosswalk, it means someone is about to walk or is walking across the road. This is one of the most recent traffic light symbols, and it catches many drivers off-guard. So don’t forget: When these lights flash, you are required to stop and wait until the crosswalk is clear.

Arrow Traffic Light Signals Explained

Red arrow

On major thoroughfares, left turns (and sometimes right turns) are controlled by arrows pointing in the direction of the turn. If the arrow is red, you must wait to make the turn until the arrow changes color.

Green arrow

A green arrow means that you can make a turn in the direction of the arrow.

• Note: In an intersection without arrow symbols, you can make a left turn on a green light when there is no oncoming traffic. To clarify this, there may be a sign under the traffic light that says “Yield to Oncoming Traffic.”

Amber (yellow) arrow

An amber or yellow arrow means that a green arrow is about to change to red. It’s legal to make your turn as long as you enter the intersection before the arrow changes to red.

Traffic Light Symbols Decoded

Lane control signals

On multi-lane highways, as well as on bridges and in tunnels, illuminated signals control traffic flow in each lane:

• A red X means the lane is closed.
• A yellow X means the lane is about to close. Move into another lane.
• A green circle or arrow means the lane is open.

Bicycle lane symbols

In cities with bicycle lanes, the traffic lights display a bicycle symbol. When it’s red, bicycles must stop, and cars can turn right. When it’s green, bicycles can go, and cars are prohibited from turning. These traffic light symbols ensure bicycles can safely cross the intersection.

Pedestrian walk symbols

Most busy intersections have signals to tell pedestrians when it’s safe to cross the road. The symbol for “Walk” is typically a green or white depiction of a person walking, and the symbol for “Don’t Walk” is a red depiction of a person standing.

Everyone knows what these symbols mean, but what about when they are flashing? Here’s the explanation: If you’re in the intersection, keep going to the other side, and if you’re on the curb, stay there and wait for the next Walk signal.

Just as they do for yellow lights, people interpret this rule in various ways.

FAQs

Do traffic lights have sensors?

Many do, but they may not work all the time. Some sensors are designed to detect cars only at off-peak hours, and some regulate the timing of the traffic lights on heavily traveled roadways only at certain times of day. There are different types of sensors, including:

• Inductive loops in the roadway;
• Cameras;
• Infrared detectors;
• Radar sensors.

To improve your chances of having a detector sense your car and change the light, it’s important to pull up as close as you can to the white line denoting the start of the intersection.

Is taking a right on red always legal?

It has been legal to make a right turn on a red light since 1973, when the rule was adopted to cut down on emissions from idling vehicles. After coming to a full stop, you can make a right turn on a red light in all but these three situations:

• You see a sign that prohibits a right turn on a red light.
• You see a traffic light with a red arrow pointing to the right. In this case, you have to wait for the arrow to turn green.
• The intersection has bicycle lane traffic light symbols. You can’t turn right when the bicycle symbol is green and your arrow is red.

Tip for travelers: In states such as California, New York, Florida and 34 others, it’s legal to make a left turn from a one-way road onto another one-way road when the light is red. If you’re waiting for the light to change to make your turn, and you hear honking behind you, you’re probably in one of those states.

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