STREETS & HIGHWAYS/LED lights save energy in city’s traffic signals

In a move to reduce electricity costs, Cape Girardeau, Mo., has placed energy-saving light bulbs in nearly all its traffic signals. The new bulbs will reduce the city’s power bills for the signals by about $13,000 annually, says Tim Gramling, assistant director of the Public Works Department. The city has 13 intersections with traffic signals; the bulbs have been installed in 12 of them.

The new bulbs were part of a $92,000 traffic-signal renovation that occurred late last year. During that time, the Public Works Department installed new traffic-signal heads (the hanging devices that contain the red, yellow and green lights). The department also replaced incandescent bulbs with light-emitting diode (LED) bulbs in the city’s traffic lights. The city hopes to have the LED bulbs in all of its traffic signals by the end of the summer, Gramling says.

In addition to the projected energy savings, the LED bulbs should require less maintenance, Gramling says. The bulbs carry a five-year warranty and are designed to last about 20 years. By contrast, the incandescent bulbs usually did not last much more than a year. “[The LED bulbs] are going to save us a lot of time in having to go out and respond [to a traffic light going out],” Gramling says. “We don’t have to worry about that as much right now.”

Gramling began to consider making upgrades to Cape Girardeau’s traffic lights when he joined the Public Works Department more than five years ago. “The traffic signals had been installed back in the 1970s,” he says. “A lot of the heads were cracked, and moisture would get in there and cause problems.”

Then, a couple of years ago, Gramling read a magazine article that detailed how Kansas City, Mo., had replaced the mercury vapor bulbs in its street lights with more energy-efficient high-pressure sodium bulbs. “When I saw that, it gave me the idea that we could do something like that,” he says.

Cape Girardeau received an $83,000 loan from the Missouri Department of Natural Resources, which has a loan program for energy-saving projects, for the traffic-signal renovations. (The remaining $9,000 for the project came from the city’s General Capital Improvement Fund.) The loan carries an interest rate of 4.1 percent and a 75-month term. The city’s annual payment on the loan is based on the estimated savings in electrical bills that the LED bulbs will provide, according to Gramling. After the loan is paid off, the city will begin to realize the savings.

The city purchased the LED bulbs, manufactured by Farmingdale, N.J.-based Dialight, from Davenport, Iowa-based Brown Traffic Products. The total cost for the bulbs was approximately $40,000.