The use of light-emitting diodes (LEDs), in traffic signals has become popular among local governments as a means to save energy in recent years. Now, several counties are testing how effective the lights would be for street lighting, according to an article from the Washington-based National Association of Counties (NACo).

King County, Wash., and Arlington and Fairfax counties in Virginia are conducting pilot programs to test the use of LED lamps, also known as luminaires, according to NACo's article. King County recently concluded the first phase of its pilot test to determine whether it could replace 1,800 of its high-pressure sodium (HPS) lamps with LED lights.

King County tested luminaires from two manufacturers on a two-block section of road in Redmond, Wash. While the county's Senior Signal and Illumination Design Engineer Linda Mott says in the article that she was pleased with the "clean crisp light" provided by the luminaires, a report on the pilot test found that neither LED fixture provided light levels within 10 percent of the HPS lamps, the criterion set by the county's traffic engineering division. Mott called the results "pretty disappointing."