Forty-three municipalities, including nine in Lackawanna County, have signed up to have incandescent traffic lights replaced with LED — light-emitting diode — bulbs, which require less energy to illuminate and don’t have to be changed as often, said Kurt Bauman, manager of the alliance’s energy assistance program.

“Incandescent bulbs go out more frequently,” he said. “LED bulbs are guaranteed for five years and expected to last 10 years.”

Throop is the latest municipality in the county to approve the switch. It has 17 traffic signals at two intersections — a total of 51 bulbs to be replaced.

Replacement work costs about $3,500 per intersection — 25 to 30 bulbs — including the price of the bulbs and installation, Mr. Bauman said.

Brightness is the most noticeable difference between LED and incandescent bulbs, Mr. Bauman said.

Drivers may also notice a small ring within the light itself, he said.

“They’re somewhat distinguishable,” he said.

LEDs got a trial run in Clarks Summit earlier this year. Mr. Bauman’s organization partially funded the purchase and installation of the lights at four intersections.

“We know that converting incandescent bulbs to LED bulbs offers energy savings,” he said. “We just wanted to make sure that the funding we provided the municipalities would be an incentive.”

A post-project energy audit estimated the town will save $3,600 this year.

The organization has applied for grant money to assist municipalities with the cost of replacing the lights. It would need about $1 million to fully finance projects in all interested municipalities. If necessary, municipalities have to sign a letter agreeing to pay matching funds toward the project.