Solid State Lighting - Traffic Lights in California

CASE STUDY: TRAFFIC LIGHTS IN CALIFORNIA

One early LED success has been in traffic lights. Because LEDs produce red, yellow, and green light directly, no filter is required, so LED traffic signals require only 10% as much energy as incandescents.

Equally important, LED traffic lights can last up to ten years, compared to only two years for incandescents, reducing the need to close down intersections for maintenance. And when they do fail, they do so gradually, so failures are not dangerous and repairs are not urgent. This results in less traffic congestion, reduced maintenance costs, and less strain on a municipality's workforce.

Another critical advantage is that their low power consumption allows LED traffic lights to be run off of backup batteries for two hours or more. In the event of a power outage or natural disaster, this feature helps maintain order as the city works to respond.

In 2002, California established efficacy standards for new or replacement traffic signals that required the use of LEDs. Two years later, these standards were extended to pedestrian traffic signals.

In 2004, with half of vehicular and pedestrian traffic signals replaced, peak electricity demand savings were approximately 60 Megawatts statewide. Once all signals are replaced, the reduction in peak demand will reach 120 Megawatts, enough to power almost 120,000 homes.