ST. CLOUD, Minn. (AP) - Finding the perfect street light is no simple task.
New lighting technology means engineers can choose lights based on how widely the light is transmitted, the color of the light and the extent of shadows and glare. So a neighborhood can have a warm, cozy feel while intersections can be brightly lit while limiting glare.
“It’s like comparing a guitar player to an orchestra,” Traffic System Manager Blake Redfield said of the new technology.
LED lights give cities a number of options to find street lighting that best serves the area they are in. And St. Cloud has an unusual lab where those lights can be tested so the most efficient ones are purchased and put on city streets.
Redfield, who works for St. Cloud and Stearns County, created the lab three years ago to test the quality of LED street lights. The city was looking to put lights on Kilian Boulevard, and Redfield said they heard “outlandish” claims from manufacturers about how well LEDs worked.
So the city created its own to test the lights and find out how well they work.
“We wanted to do our homework and we did,” he told the St. Cloud Times (http://on.sctimes.com/1gH3exI).
Starting this year, St. Cloud plans to put LEDs in all new street lights. While more expensive up front, LEDs only need to be replaced every 10 years, compared with every three years for traditional lights. Putting in LEDs can increase a project’s price by about 15 percent.
“They’re expensive, so we want to make sure we get the best bang for our buck,” Redfield said.
And the improving technology has lowered costs of LEDs over time. Four years ago, a LED street light would cost $1,300, but now the cost averages $250.
“Now we almost can’t afford not to put in LED,” he said.
To make sure the city is purchasing the best lights possible, Redfield puts them through several tests that he designed. In the past, Redfield has found light patterns that are not symmetrical and lights that create a shadow around the light pole.
One test uses a light deck, which is a platform with a series of holes on it. At each hole, the light’s intensity can be tested so Redfield knows how well the light shines directly below the lamp and further away from it.
He also can test how much light can be seen above the fixture, which is important for limiting light pollution.
The lights also are put on a light tower, which can move it up to different heights. That allows him to see how wide the light spreads out and if the light is uniform.