Traffic signals that use LEDs consume 80-90 percent less energy and generally last 5-7 years, compared to just a year for a comparable incandescent light signal. LED traffic signals also offer significant peak demand savings since they operate 24 hours a day (source: Consortium for Energy Efficiency). But, they also cost more.

Municipalities considering LED traffic signals have to weigh the first costs against the operating costs to decide which is best. Many are finding that changing out red and green lights have a good payback but yellow lights, which are not on as much, do not. Therefore, the answer to The Puzzler on NPR's popular radio program, Car Talk, is that you don't see many yellow LED traffic lights because the economics are not as good, not because LED's don't come in yellow (they do!). See our Energy Ace Newsletter Winter 2004-5