What is a Street Light?

Mary McMahon

A street light is a light installed at the edge of a roadway to illuminate the side of the road. The history of lighting streets and roadways is ancient, with evidence that many communities in the Ancient World encouraged citizens to keep outside lights burning through the course of the evening for navigation and safety. The earliest formal street lights operated as a municipal service were gas lights, which were handlit by a crew of people every evening. Eventually, gas lighting was replaced with electric lighting, and street lights today are usually fully automated.

Street lights are commonly installed along roadways to provide illumination for night drivers.
Street lights are commonly installed along roadways to provide illumination for night drivers.

The purpose of a street light is not to illuminate the roadway; at night time, drivers should be using headlights, which will illuminate the road for them. Street lights light up the side of the road, alerting drivers to potential hazards and situations which they need to be aware of. They can also be used to signal the presence of an intersection, so that a driver can be prepared for cross traffic or get ready to turn onto a side street.

Street lights are a source of light pollution, which prevents people from seeing the stars at night.
Street lights are a source of light pollution, which prevents people from seeing the stars at night.

Street lights are also a safety feature. Well lit areas tend to be less dangerous after dark because it is harder to commit a crime when the scene is fully illuminated. Street lights which keep parking lots and streets lit up at night make it safer for citizens to be out after dark. They can also be useful for navigation for people walking, allowing people to clearly see the sidewalk and surrounding area.

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Street lights are sometimes criticized as a source of light pollution. A number of manufacturers have responded to this with designs which are intended to reduce light leakage. The poles on which street lights are mounted can also be a hazard, as people may hit them in cars, and the poles can also fall in storms or in freak incidents as a result of metal fatigue. A street light can also develop electrical problems which cause the entire pole to become electrified, although this is rare.

Many street lights today operate with the use of solar sensors which activate the light when it gets dark. Some are also solar powered, allowing them to operate on standalone poles without the need for an energy source. Some cities may use timers for their street lights, primarily in the case of older systems which have not been upgraded.

Municipal authorities usually appreciate being made aware of street light outages. If someone notices that a street light is out, he or she can call the city department or the electric company to report the outage.

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Discussion Comments


Well, after reading this, and reading the posts 1,2,3,4. I feel surprised. Because I am from China. Here people are everywhere. And lights are here and there. We live in a high people and lights density region. How important the street lights are for people! Safety and convenience. Reading this article, I realize how important the outdoor lights are!


@lighth0se33 – It depends on whether the street light is solar powered or electric. If it doesn't have cables running to it, then it is likely solar. If the street lights are all connected by cables, then they are electric.

Yes, it is scary to find yourself outdoors in sudden darkness. I was walking my dog down my street at night one time when the power to the whole area went out. Even the street lights shut down, and I stood still, not knowing what to do.

Luckily, I had my dog with me, and he can see in the dark. I had to place my trust in his ability, and sure enough, he led me home, even though he seemed to take the long way.


My town square is mostly lit by street lights, but there are some back alleys that remain dark. I am always afraid to walk down there, because I have heard of several crimes that have taken place in the dark alleyways.

If I remain on the main square, the lights are so bright that I can tell who is approaching me. The only dark areas are under the grove of trees in the center, but I always avoid that at night.

I have often wondered what happens if the electricity goes out. Do the street lights have another source of power, or do they shut off, as well? Being caught off guard by sudden darkness would be so scary!


@orangey03 – I think it is kind of a good thing that street lights attract bugs. The more of them that swarm around the light, the less there are down here at windshield level to paste themselves onto my car.

When I'm driving through country roads with no street lights, I can hear so many bugs hitting my windshield that it sounds like rain. When I get home, I have yellow juice and even a little blood all over the glass, and I have to clean it just to be able to see through it the next day.

City streets still have plenty of insects, but they are mostly flying high around the glow of the street lights. I wish all roads would get these.


There is a street light with a solar sensor right in my yard. As soon as the sun has set, it comes on like clockwork. It stays on until the sun rises the next day.

The bulb has a blue hue, and it attracts insects like honey. It also attracts bats, which eat the insects, so I try to stay away from the area.

It is so nice to have my yard partially illuminated by this street light. I know it is meant for the road, but I benefit from it as well. I can see if any wild animals are lurking in my yard, and I think it probably keeps strangers from walking up here.

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