That move is expected to save the city more than $220,000 annually in energy costs and replacement expenditures - meaning the investment will be paid off in less than four years.

Because the LED lights last five to ten times longer than conventional incandescent bulbs the total savings are expected to easily exceed more than $1 million over the life of the new signals.

"We had planned to phase-in LED lights over the next several years, but when we started looking at the numbers, we realized there was a significant opportunity to realize a tremendous savings by getting them all done at once," said Mayor Bill Haslam.

The city has been involved in an ongoing program to gradually replace incandescent bulbs in traffic lights with LED signals. About 20 percent of them have been replaced over the past few years.

But the one-time, $781,500 investment will allow Knoxville to complete the program within a relatively short period of time - and realize the accompanying savings.

LED signals cost more than traditional incandescent bulbs but they consume just 10 percent of the electricity and last several years longer.

A typical LED traffic signal, for example, has a lifespan of 5-10 years whereas a typical incandescent bulb has to be replaced at least once a year.

Replacing the incandescent lights with LED signals will also allow the city's Traffic Engineering Department to reallocate staff time - that had been devoted to the annual light changes - to meeting other needs in the city.

"We're looking forward to completing this job," said Steve King, director of the city's Public Works Department. "Reducing the amount of time staff spends changing light bulbs will allow us to concentrate on preventative maintenance in other areas."

The project is the first major implementation initiative associated with the City's Energy & Sustainability Initiative, which was kicked off last August.

As part of the initiative a 15-member Energy & Sustainability Task Force - including members from the City of Knoxville, Knox County, TVA and Oak Ridge National Laboratory, Knoxville Utilities Board and environmental groups among others - has been charged with developing a strategic plan for reducing energy consumption and enhancing the City's overall environmental sustainability.

Madeleine Weil, deputy director of Policy & Communications and chair of the task force, indicated that the LED replacement program is a great first step in achieving the group's goals.

"In addition to saving the city money, the LED traffic signals will reduce environmental impacts associated with the city's energy consumption," Weil said.

The city anticipates that the LED signals will conserve 3.8 million kilowatt-hours of electricity, or roughly the amount that 316 average households would use in one year. That will reduce city government's annual carbon dioxide emissions by approximately 2,625 tons, or 3.5 percent annually.

The Energy & Sustainability Task Force will meet on December 12th to discuss findings of the city's new Energy & Emissions Inventory.

More information about the initiative is available at http://www.cityofknoxville.org/policy/energy/