What Are the Dimensions of a Traffic Light?

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Traffic lights are made in many different options. They can include three, four, or five different lenses in varying patterns. There are two main sizes of three-lens traffic lights used around the world. These different designs are available with either an 8-inch or 12-inch lens pattern.

The 8-inch lens pattern featuring three lights stands approximately 30 inches tall. It has a width of 9.5 inches. The depth of the 8-inch lens light is 6 inches deep. The 12-inch lens pattern traffic light featuring the three-light pattern is 42 inches tall. It has a width of 13.5 inches and is 8 inches deep. The measurement for both of these traffic light options is based on the main body of the light design and doesn’t include visors that may be included.

Different factors affect the size of the traffic light placed in certain intersections. Let’s uncover some of them.


Different states throughout the United States and countries around the world chose to use one size of traffic light over another. For example, you will often find the larger 12-inch lens traffic light in places like New York City or Los Angeles. This is due to high volumes of traffic in these areas. The larger lights make it easier to see from further distances that vehicles are traveling.

The United Kingdom opts for the 8-inch lens traffic lights. This is desired due to their ability to manufacture traffic lights of this size with highly visible specialty lenses. This makes it possible for drivers to see clearly without the larger surface area.

There are hybrid designs for traffic lights, which can be found in places like Canada. These lights feature one or more 12-inch lens signals combined with smaller 8-inch lens signals on the same traffic light setup. While these designs are not common in most places, they do serve their purpose for the jurisdictions where they are utilized.

Traffic Conditions

Not every intersection requires the same type of monitoring. However, when you are driving in heavier traffic such as what is found in cities like Detroit or San Francisco, you want to know that the lights are visible even at a distance. Most transportation departments will place the larger lens traffic lights in these areas for those purposes. Intersections that have lighter traffic and slower speed limits often take advantage of the 8-inch lens traffic lights. This helps to save on the budget for these municipalities as well.


Each city and state throughout the U.S. has its own ordinances that they implement. These laws and regulations are incorporated to keep people in their areas safe and to minimize accidents from occurring. Most of these localities have a department of transportation (DOT) system in place to oversee that the ordinances are carried out. 

Among the standards that the DOT in each state oversees is the placement and sizing of the traffic lights. The regulations give in-depth detailing as to how high the lights should be hung, the types of lights that should be used and the distance at which the traffic lights should be visible. Not following these standards could be costly to the department in question.

Some municipalities may set their ordinances to ensure that their spending stays within budget. When this occurs, the costs of the different types of traffic lights needed may play a role in the design that is used. 

Additional Features

The four-lens and five-lens traffic lights allow for additional types of lenses to be used. The main options are yellow (amber) and green arrows. These allow drivers the ability to turn when another direction of traffic has the right of way. These additional lenses can either be added to the bottom of the standard three-lens design traffic light or positions on the sides. This will affect the length or width of the traffic light, as well as the weight.