LED: A power-saving alternative

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Narrator Says:

The technology may not be new, but the King County Road Services Division may be laying new ground by using it in a whole new way, and saving a lot of labor, energy, and money along the way.

King County maintains about 1,800 street lamps countywide, almost all what you’re used to seeing, shaped like the head of a cobra, and emitting an orangey light.

But those may soon be replaced by a light with a new look, that relies on substantially less energy to provide its light.

Norton Posey, a signal and design engineer at the county explains the difference.

King County Signal and Design Engineer Norton Posey Says:

What you see here is examples of street lights. Next to me is a high-pressure sodium lamp that we're using and to my far left is an LED street light that we're using on our pilot project. The high-pressure sodium is a gas-charged lamp that has a life cycle of approximately one year, and to my far left is the Leotech street lamp, which is an LED or a light-emitting diode.

The advantage of using LED street lights is that we're able to save as much as 70% in energy. The other advantage is that we have to replace the lamp in the high-pressure sodium once a year, where we can see upwards of [a] five to eight year life cycle for the LED street lights. This ends up saving labor, materials cost and reduces our street light cost to the county.

Narrator Says:

The five to eight year life cycle also mean less physical waste in the form burnt out bulbs.

The LED street light program is in its pilot phase.

In august of 2008, the county installed a total of eight LED street lights, four each from two different manufacturers.

They went in along NE Cedar Park Crescent Road in Redmond.

King County is among those on the cutting edge of efforts like these, already having converted some traffic signals to LED.

King County Signal and Design Engineer Norton Posey Says:

What the vendors have told us that we're seeing as much as a 70% reduction in energy consumption with the LED vs. The high-pressure sodium. Part of this pilot project is also to monitor that power usage. So where we've installed these we can see how much power was being used by the high-pressure sodium lamp, and then we can see how much power's being used by the LED, and then make that comparison.

Narrator Says:

Aside from the energy savings, that engineers believe could cut the cost the county’s street lights in half, there are challenges that must be addressed before the LED’s could be implemented countywide.

Manufacturers are still trying to achieve the same light output from an LED street lamp, that current lamps can emit.

King County Signal and Design Engineer Norton Posey Says:

This is very similar to what happened with the signal LED's, when they initially on the market they didn't meet the standards of the industry, the colors weren't quite right, the brightness wasn't quite right. But over several years of working with those manufacturers they developed a product that you see today and that is in a lot of the signals the county uses, if not the cities or the state across the country.

Narrator Says:

As far as the project’s future, county engineers are considering testing out LED lamps from two more manufacturers, pushing the total to four, as they begin to assess whether LED would be a viable and practical alternative and save the county substantial amounts of energy and money.