All About Traffic Lights: Traffic Light Size, Weight, and More

From a distance, traffic lights look no bigger than your average cereal box. They also tend to look small up close, which can be because they’re 18 ft. in the air. But when they’re on the ground, how big are traffic lights exactly? How much do they weigh? Find out the answers to these questions and more.

How Big Are Traffic Lights?

The average traffic light has a height of about 30 inches, with each lens having a width of about 9.5 inches and six inches deep. The lenses of an average traffic light are as big as a human head. Other traffic lights can go as tall as 42 inches. Their lenses are often 13.5 inches wide and eight inches deep.

How Much Does a Traffic Light Weigh?

Traffic lights can weigh anywhere between 30 and 50 lbs. depending on their material. Aluminum traffic lights generally weigh more than plastic or polypropylene traffic lights.

What Are the Parts of Traffic Lights?

Most traffic lights have housings of molded polycarbonate with supporting poles of galvanized steel.

The lamps usually have LED light sources layered with a polished metallic reflector. The lenses are typically plastic or tinted glass and have a visor or hood made from molded polycarbonate or aluminum.

Traffic lights also have an electronic controller in a weatherproof housing that’s buried in one of the corners of an intersection. However, some traffic lights have electromagnetic sensors scattered in different areas of the roadway.

How Are Traffic Lights Installed?

Installing traffic lights involves making underground electrical conduits between each signal support location and the controller. The traffic light signal heads have their own mounting points. The wires pass through them before they connect to another set of wiring.

Where Are Traffic Lights Located?

Traffic lights are placed in areas with higher traffic rates than others. They are not placed at every intersection or crossing to avoid confusing drivers.

The size of a traffic light varies, depending on its intended location. You’ll most likely see 42-inch traffic lights in areas like New York City given the traffic conditions there.

How Much Do Traffic Lights Cost?

Traffic light installation can cost anywhere between $200,000 and $500,000, depending on the complexity of the intersection. This price range also includes marking pavements, utility adjustments, pedestrian access ramps, and other features. Whether the traffic light has a vehicle detection system or not also affects the cost.

Why Do Some Traffic Lights Fail to Detect Small Vehicles?

Many traffic lights in the US have vehicle detection systems to help regulate traffic flow. However, there are cases where the traffic controller couldn’t detect small vehicles like bicycles and motorcycles, failing to give them the right of way at certain stops.

One of the reasons this happens is that the induction loop sensor is programmed to detect vehicles of a certain mass. Bikes and motorcycles tend to have a smaller mass than the average vehicle, which stop lights are designed for.

Adjusting the sensitivity of the induction loop sensor will ensure that it’ll detect smaller vehicles. However, that might also create problems because it will increase the risk of false triggers.

When Did We Start Using Traffic Lights?

The first traffic light was built in 1868 in London, England. It was manually operated and consisted of a green and red gas lamp with semaphore arms.

Fast forward to 1914, the first electric traffic light was installed in Cleveland, Ohio. It had green and red lenses with a warning buzzer that signaled it was about to change.

The modern traffic light has undergone several changes since then. Some variations have additional signals like arrows to indicate that the driver has a right of way at certain stops.

Some traffic lights also have more advanced controllers that let them detect traffic flow and time of day on their own. This lets them adjust the sequence of operation depending on road conditions.

Redesigning the Modern Traffic Light

Developers have begun to redesign the modern traffic light by improving its capabilities and integrating artificial intelligence (AI) into its system.

A couple of cities on the west coast have traffic lights that are controlled in real-time. These traffic lights gather data from various sources, like transit dispatchers, mobile phones, navigation programs, weather service, and emergency responders, to adjust traffic conditions accordingly.

What Should You Do When a Traffic Light Goes Out?

The standard protocol for drivers is to treat the faulty traffic lights as a stop sign. So they should come to a complete stop at intersections and roadways where the traffic lights aren’t working. In the case of a four-way intersection, the rule is that the driver should treat it as a four-way stop.

Breezing past broken traffic lights can be tempting. However, while their malfunctioning state can be an excuse to disregard them without any consequences, failing to stop also increases the risk of getting into an accident.

In the first half of 2022, the National Highway Traffic Safety Administration (NHTSA) recorded 20,175 traffic casualties, a higher number than the previous 2021 data.

Speeding, reckless driving, driver inattention, and lack of driver training are some of the main reasons why road accidents happen. So you might want to think twice about sneaking past a traffic light.