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The City Council is expected to approve funds tonight for completion of the High Efficiency Traffic Signal program that will govern the city’s intersections with signal lights that burn cheaper, longer and brighter. 

The switch from inefficient, incandescent lights to light emitting diodes began in late 1999 and is already saving the city as much as $120,000 a year, according to a staff report. The city has already changed the red lights at all 126 intersections and the green lights at about 32 intersections. The city’s energy officer is now asking the council for $120,000 to complete the transformation to LED lighting. 

The upfront cost will be offset by a PG&E rebate of $40,000 and an estimated $33,000 in energy savings over the first two-and-a-half years the lights are in use.  

“The up-front investment is significantly higher,” De Snoo said. “The cost of a traditional, incandescent light is about 50 cents and the LED fixture costs about $100.” 

But De Snoo said the savings are huge once energy savings are factored in. LED lights use about 85-90 percent less energy than incandescent lights use to illuminate traffic signals. In addition they have an average 10-year life span compared to incandescent lighting, which has an average life-span of 13 months. 

According to the staff report recommendation, the LED lighting will reduce carbon dioxide emissions, from electric generation plants, by as much as 156 tons annually. 

De Snoo said the lights will be changed by the Department of Public Works as part of the regular traffic signal maintenance. He said the remaining 94 intersections should be converted to LED lighting during the next 12 months. Currently there are no plans to change yellow traffic lights because they are illuminated for an insignificant amount of time.  

Caltrans spokesperson Jeff Weiss said the state has been using LED lighting in traffic signals since 1995, soon after the technology became available. “The state has saved millions of dollars in the last few years,” he said. “Caltrans maintains thousands of traffic signals throughout the state and with 85-percent savings in energy costs it adds up awful quick.” 

De Snoo said the main difference between incandescent and LED lighting is that LED “glows cold.” 

“Incandescent lights work on a heating coil, once the coils are hot enough they glow,” De Snoo said adding that only about five percent of the energy used to light an incandescent bulb is actual light. “So really what you have is a little electric heater that glows.” 

LED lighting, which is used in cellular phones, Palm Pilots and other battery-operated devices, emits a photon that is generated when energy connects with a chemical compound in the fixture. The photon that comes out as light is already colored so there is no need for shaded lenses.  

In addition to cost efficiency, the LED lighting is also safer according to De Snoo. Since the lights are less likely to fail - only one of the LED red lights that were installed in 1999 has failed so far - there is less chance of drivers becoming confused, which often occurs when traffic lights fail. Also city crews will be less likely to be called out to repair failed lights during dangerous high-traffic conditions. 

According to the official web site of the City of Scottsdale, Ariz., which switched to LED traffic lighting three years ago, there is less chance of “phantom illumination” which can occur from lens reflection when the sun is low. 

“Everything about these lights is good,” said Energy Commission Vice Chair Susan Ode. “The city has been very careful about testing the red lights and it’s clear they are a very smart thing to do.” 

De Snoo said LED lighting for the home is not yet available because the technology for white light has not yet been refined. “Only a narrow band of colors are available right now,” he said. “But it’s only a matter of time before LED lighting is available for the home.”