"The incentives are going to be a big lift," Stober said.
Traffic engineers across the region are furiously writing grants to take advantage of government-inspired energy-conservation promotions.
"Everybody's getting on board," said Louis Fiorito, the director of Upper Darby's electric department, who plans to convert the remaining half of the township's 100 signaled intersections that do not now have LEDs.
In Philadelphia, the new deployment will save about 9 million kilowatt-hours a year - enough electricity to power more than 1,000 homes. The city's annual electric cost will go down about $1 million, Stober said.
LED technology has been around for decades, but the devices have received much attention lately as their price has come down and they have become more affordable for household use.
Municipalities began using LEDs in traffic signals in the 1990s. Peco spokeswoman Cathy Engel said that about half the region's 165,000 traffic lights were now LEDs.
The city, which operates about 85,000 traffic signals, was an early adopter of LEDs, which can be distinguished by the eye because they are composed of a grid of individual lights rather than a single incandescent bulb.
Joseph M. Doyle, Philadelphia's chief traffic engineer, said the city converted all its red lights to LEDs in 1998. Red was the only color available then.
Though substantially more expensive than incandescent lights - a 12-inch unit costs as much as $155, compared with $3 for an incandescent - LEDs have other advantages. They last five to 10 years, so they require much less maintenance. And they use only about 10 percent of the electricity a conventional bulb uses.
