How Big Is A Traffic Light? Let’s Find Out The Traffic Light Dimensions!

How Big Is A Traffic Light? Let’s Find Out The Traffic Light Dimensions!

If you have ever seen a picture of a traffic light beside a person and went, “wow, that’s huge!” you are not alone. 

You’re not the only one who thought these were teeny tiny small devices hanging on the side of the road. 

Traffic lights are usually hanged 18 feet above the ground; that’s like a two-story building high! This explains why they look so small from where we stand.

It’s not every day that we wonder about the traffic light dimensions, but since you’re here, why not learn about a few interesting facts about these machines. 

So, without wasting any more time, let’s start talking about some facts!

Dimensions Of A Traffic Light

Traffic lights come in various patterns and designs; you will find at least five to six different lens designs worldwide. 

However, all these patterns are usually available in only 2-sizes: An 8-inch pattern and a 12-inch pattern.  

The 8-inch pattern comes with three lights, approximately 30-inches in height and 9.5 inches in width. 

These lights are usually 6 inches deep, and each lens can be as big as an average person’s head. 

However, 12-inch pattern traffic signals are a lot bigger in size than the other pattern. A typical three-light pattern 12-inch signal is approximately 42 inches tall. It is usually 8 inches deep and has a width of 13.5 inches. 

However, the sizes and patterns of these lights may vary depending on different factors. 

Some places prefer the 8-inch signal, while others use the 12-inch light. But both are widely popular in various places in the world.

What Affects The Size Of A Traffic Light?

As mentioned before, the size of the traffic signal depends largely on some issues like location, traffic population, traffic rules, and laws. 


Many densely populated states usually go for the bigger traffic signal, i.e., the 12-inch light. 

Highly populated areas often have a high volume of traffic; hence, the machine’s bigger size makes it easily visible to the drivers from a considerable distance. 

Many states around the world, including the USA, prefer the larger light over the other. You will only find the 12-inch light all over New York and Los Angeles.

However, if you ever visit the United Kingdom, you will see that they mostly prefer the 8-inch light. 

But does it mean that the traffic population is very low in that area? Obviously not! So why go for the smaller version? It is because 8-inch lights come with special customizable features that the other one does not support. 

Hence, you can manufacture these with highly visible special lenses, easily noticeable from a great distance. 

Therefore, you don’t really need a larger size to make the light visible from a further distance.

However, an 8-inch and a 12-inch pattern are not the only two types that people use. Canada uses a unique form of hybrid lights that combines the feature of both lights. 

The hybrid design comes with one or two 12-inch lenses with a smaller 8-inch lens. However, this pattern is not very popular in other parts of the world.

Traffic Conditions

Busy road like highways is jam-packed with traffic almost all the time. Some places in Detroit and San Francisco always have heavy traffic. 

Hence, these places require strict control and visibility of the signals, which is why the 12-inch lenses come in handy for these locations. 

But intersections that usually have lower traffic are less chaotic; hence most transportation departments opt for the 8-inch lenses for these places. The bigger lenses are generally costly, heavy, and also challenging to set up.

This is why constructors take advantage of the smaller version in low-traffic areas saving them a considerable expense as well as from the nightmare of setting up this giant monster.


We all know every state follows specific traffic rules and regulations, but it may come to you as a surprise that these rules also state the size, distance, and hanging height of the lights. 

Yes, they even mention how high you should be hanging these lights. These rules are essential to maintain safety on the road and reduce the chances of accidents. 

The department of transportation (DOT) of each respective location is responsible for carrying out the written rules at all costs.

Hence, if the rules state you have to use a 12-inches lens, you must use the 12-inches traffic signal no questions asked.  Not abiding by these set standards can put the department in trouble. 

Moreover, some states construct these standards to ensure that their expenses stay within budget; therefore, the DOT only follows whatever rules are set by the higher authorities.

Understanding The Different Signals

We all know traffic signals feature three colors, i.e., Red, Yellow, and Green. But there are different forms of these signals, for instance, steady lights, flashing lights, arrows, and many more. What do these different patterns mean?

Let us start with the basics; a steady red light means that the driver must stop his vehicle entirely and remain in that position until the color changes. A steady yellow color indicates that the green light will be changing soon. 

The yellow signal helps the drivers to lower their speed and stop smoothly at a red light. Abrupt breaks can lead to dangerous accidents; hence the yellow light comes in handy in these situations. And lastly, a green signal means you can start driving your vehicle. 

The flashing lights generally indicate dangerous intersections on busy roads. These flashing signals warn the driver about the crossroads. However, the colors work the same as the steady lights; that is, red means “stop,” and yellow means “slow down.”

Now let’s talk about the arrows; a red arrow signal stops drivers from turning in the direction of the arrow until the lights go green. 

A flashing yellow arrow means that you can turn in the direction but slowly and carefully. And a green arrow indicates you are free to drive towards the direction of the arrow.

Components Of A Traffic Light

A traffic light may look like a simple device, but it is not only about displaying the red, yellow, and green light. This machine comes with various components, which keep this machine functioning. 


The controller is like the nerve center of a traffic light. It is the most vital component of the device, but it is not visible from the outside. 

Generally, a single controller can control several intersections to make sure the flow of the vehicles is smooth across all the regions. 

This part includes various sub-accessories like the logic rack, detector card, different software, and the communication medium. 

Moreover, this part of the device can also function in situations like making emergencies like police cars, ambulances, or fire trucks.

Light Bulb

Light bulbs are one of the most critical parts of a traffic signal. What’s a traffic light without a light bulb, right? But you will be surprised to know that these lights are no different from the regular bulbs we have at home. 

These come with a reflective casing featuring different colors that are projected by the spotlights. 

The light passes through these reflective glasses, which amplifies the brightness of the lights and delivers bright yellow, green, and red colors. These 100-150 watts can operate 24/7 without losing their brightness.  


A lantern features different types like a body type, lamp type, or display type. These different categories are selected based on various priorities and budgets. 

There are many more components of a traffic signal, including pedestrian detectors, target boards, cabling, poles, and cameras. All of these parts function together to ensure smooth traffic control every day.


The installation process of a traffic signal is undoubtedly complex. The engineers put six underground electrical channels between the controller and the signal support system for installing the device. 

The engineers pull several connecting wires through electrical channels. The power to control the signals remains attached to the controller location. Many devices come with sensors that are also attached to the controller. 

The constructors mount the support system in place and pass several wires through the base and the signal mounting point. 

The signal stacks also remain connected with the supports. Lastly, the wiring is attached to all the elements of the device. 

Each lens to finish off is adjusted to ensure they are visible from afar. Next, the sequence timer is set according to the specific timing determined by the engineers. Then the whole system goes through several test runs to make sure everything runs smoothly.

Final Words

That is all you need to know about the traffic light dimensions and everything in between. We hope this article cleared out your confusion about the actual size of a traffic light. 

Furthermore, hopefully, you got to learn a bit more about the different factors of this device. Till next time don’t forget the traffic rules and drive safe!

About the author

Johnny is dedicated to providing useful information on commonly asked questions on the internet. He is thankful for your support ♥

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