LEDs signal a bright future for Iowa city
Davenport, Iowa, is saving its taxpayers more than $20,000 per year in energy costs, and, at the same time has made its streets safer for motorists. In the fall of 2000, Des Moines, Iowa-based MidAmerican Services installed light-emitting diode (LED) signals in the city’s traffic control system. The city paid for the project through the resulting energy savings.
Installed at 170 of the city’s intersections, the new signals consist of lights that consume seven to 10 watts of electricity each; the previous lights (incandescent) used about 150 watts each. The energy savings come to approximately 2.1 million kilowatt hours per year.
LED signals do not burn out all at once. Instead, they gradually degrade diode by diode, leaving the traffic signal in operation. The failure of a single LED light cell does not reduce the signal intensity or create a dark spot, and almost 100 percent of the energy emitted is visible light.
The LED signals last seven to 12 years, freeing up maintenance crews, who now can spend more time on other projects. “We have had very little maintenance [with the LEDs]. We are devoting that [extra time] to roadway lighting maintenance. We have cut our outages by about 60 percent simply because we are letting our crews concentrate on that,” says Mark Berendes, traffic control superintendent for the city.