2006-12-28 / News

RIDOT completes traffic signal change over to LED technology

Program saves the state more than $500,000 annually

Just as residents try to save money on electricity by switching to energy efficient light bulbs, the Rhode Island Department of Transportation (RIDOT) is realizing significant savings by changing out the bulbs in all of its traffic signals.

RIDOT recently completed converting 770 traffic signals to lightemitting diode (LED) lamps. The cost for the $1 million project was offset by more than $600,000 in rebates by National Grid as part of the company’s Energy Initiative Incentive Program. Additionally, RIDOT expects to realize a reduction of electricity costs of about $530,000 due to the lower-wattage consumption of the LEDs as compared with standard incandescent bulbs.

“This was huge for the Department,” RIDOT Director James R. Capaldi, P.E. said. “To be able to upgrade our traffic signals at essentially a break-even cost while saving energy and reducing maintenance costs is tremendous.”

The electricity savings is based on the fact that each LED lamp only requires 14 watts of energy as compared with 116 watts per lamp for an incandescent bulb. At one intersection alone, the savings can be dramatic. Given a typical intersection with eight signal heads that runs 24 hours a day – with only one lamp out of three on each signal lit at any given time – the average yearly electricity cost with incandescent bulbs is about $810. With LED lamps, the same intersection would see a yearly electricity bill of just $99.

The savings continue in terms of maintenance. Since the new LEDs last from five to 10 years, as compared with about one year for the old incandescent bulbs, RIDOT will save money with fewer calls for lamp replacements. Fewer calls also mean less disruption for motorists from work crews set up in intersections.

Additionally, each lamp has multiple LEDs, so the light will remain functioning even if a few LEDs have burned out.

Since July 2000, RIDOT has

required that all new signal heads include LEDs for the red and green indications. In April 2002, RIDOT required all lights in new signals to use LED technology.

The Federal Highway Administration (FHWA) also contributed funding for this project, supporting 80 percent to 100 percent of the cost. About 620 of the signals were upgraded as part of normal activities for RIDOT’s Highway and Bridge Maintenance division and the rest were refitted with LEDs as part of a low-bid construction project.

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