Seeing Signals in a New Light

They’ve always had the run of the streets, dictating who must stay and who can go. The authority of the traffic light is rarely questioned--but who knew it was quite so power-hungry?

In fact, a standard traffic light run by an incandescent bulb gobbles up 10 times as much electricity as longer-lasting devices called light-emitting diodes, or LEDs, best known as those tiny red lights that alert people that their stereos are on.

Now, in an effort to save energy as California wobbles through weeks of power emergencies, Los Angeles County is preparing to replace 5,000 red traffic lights with the new equipment.

Why just the reds? They’re on longer--59% of the time, compared with 38% for green lights--and the technology for red lights has been around for years, leading to cheaper prices.

County officials expect to recoup within two years the $700,000 it will cost to install the new equipment, mostly through lower electricity bills. Since the high-tech units last about five times as long as ordinary light bulbs, labor costs may also drop, because work crews won’t have to clamber up poles to change burned-out lights so often.

“We should have been doing this, even without the electricity crisis,” said county Supervisor Zev Yaroslavsky, who pushed for the change. “It’s a very good deal for us, and it also saves electricity, which is the name of the game.”

Cities throughout California have started experimenting with the technology in recent years, plugging in a handful of new lights at major intersections, said Virginia Lew of the California Energy Commission. But the statewide power shortage has sent interest surging, she said.

In November, the commission launched a $10-million grant program to help municipalities convert their traffic lights. The money flew out the door as cities and counties scrambled to get in line for the handouts. By the end of December, Lew said, the cash was gone and 18 municipalities--including Los Angeles County, which did not apply in time--ended up on a waiting list, hoping the state would authorize more grants.

“I think if we still had money left . . . I’d be getting 10 calls a day,” Lew said. Despite missing out on the grant funding, the county decided to buy new red lights anyway and install them in unincorporated areas by the end of the year, said Mike Nagao, a civil engineer in the county Department of Public Works. “We estimate the energy savings will be over $300,000 a year,” he said.

The city of Los Angeles, meanwhile, nabbed a $1.4-million grant to upgrade 1,800 intersections with LED pedestrian signals, the orange and white indicators that show whether it’s safe to cross the street. Glendale, among other cities, also won a state grant to convert some of its traffic lights, Lew said.

The new lights burn a tad brighter, with rows of glowing pinpoints instead of the softer shine of incandescent bulbs. Although they cost much more--light-emitting diodes can run $75 and up, while an ordinary bulb goes for just a dollar or two--the diodes consume far less electricity. A standard 8-inch stoplight uses 69 watts, while the new lights use about seven watts.

If all of California swapped its 4 million traffic lights for light-emitting diodes, the statewide saving would be almost $95 million each year, according to the California Energy Commission.

In Santa Clarita, one of the local cities to have upgraded some red lights, the electricity bills are already dropping. Energy use has dipped 40% at one intersection, while another posted a 34% drop, said traffic engineer Norman Baculinao.

“And those are only the reds” that have been converted, Baculinao said. “So you can imagine the savings if we changed the whole intersection.”

Amid a backdrop of daily Stage 3 electricity emergencies in California, some cities are green-lighting more than just red lights. In Los Angeles, for example, Mayor Richard Riordan announced Thursday that the city would replace the bulbs in 20,000 street lights with more energy-efficient models.

As for the traffic lights sprouting across our asphalt landscape, engineers are planning to flick on ever more diodes in the coming years. But many drivers may not even notice the keener glow as they pull up to their local stoplights.

“I can’t tell the difference,” Yaroslavsky admitted. “A red light is a red light. And I generally stop at them.”