It is believed that most people experience this experience when flying: on a clear night, looking out the passenger plane window, most cities below the plane are bathed in a bright orange glow.
This is mainly because the light is emitted by thousands of high-pressure sodium lamps.
"From the sky, most cities look like orange spots," says Ron Bednarick, a lighting expert.
But as the road lighting revolution takes place, leds are gradually replacing high-pressure sodium lamps with longer life spans and better lighting, and that is starting to change.
The total number of street lamps in the United States is estimated at 45 million to 55 million.
Of these, most streetlights are high-pressure sodium lamps and a small proportion are metal halide bulbs.
"The adoption rate of leds has probably tripled in the last two years," says Ron Bednarick, a lighting expert.
LED streetlights, he argues, have three advantages:
First, the well-designed LED street lamps emit clear, controllable and beautiful light.
A precisely designed optical element in an LED lamp ensures that light hits where it belongs, meaning less light is wasted.
Second, LED lamps have lower maintenance costs and lower energy consumption.
Since most streetlights are owned and operated by utilities, using leds could reduce energy consumption by about 40 per cent.
At the same time, the more important savings are in terms of maintenance.
As the discharge of the high pressure sodium lamp decreases, the high pressure sodium lamp must be replaced at least every five years.
The materials and labor required to replace a single bulb may cost $80 to $200.
Since LED lamps last three to four times longer than HID, the cost savings from a single maintenance can be significant.
Third, decorative LED street lighting is growing.
With the improvement of technology and the reduction of manufacturing cost, lighting manufacturers are able to provide a wider choice of decorative lighting, and can imitate the lighting design of old-fashioned gas lamps, etc., which has a great aesthetic advantage.
A few years ago, LED lighting accounted for only a small part of the road lighting market.
The high cost of leds compared to HID lights makes it difficult to convert most towns.
But today, the pace of LED adoption is accelerating as LED lighting technology advances and prices drop.
In the future, road lighting will be LED.