Harris County gives LEDs the green light

Most motorists waiting at an intersection probably think more about the cost of their time than the cost of that red light.

Harris County officials, however, have been eyeing those costs for more than a year.

The county is joining a growing list of local governments switching out incandescent bulbs for light-emitting diodes, or LEDs, embarking on a $1 million effort to begin replacing the bulbs at the 880 intersections it maintains.

LEDs cost $60 each while incandescents run $4, but the average intersection with incandescent traffic signals costs county taxpayers $2,380 a year in electric bills, said John Blount, the county's director of architecture and engineering. A test intersection the county converted to LED last year showed a projected annual cost of just $328.

Arguably more important, Blount said, is that LEDs last seven or eight years, rather than 12 to 18 months, thus cutting the $1,500 it costs every time a contractor must be sent out to replace bulbs.

"You get a lot of savings on the cost of installation," he said. "Instead of going every year and replacing them, in essence, you're going every eight years. Just like homeowners, we have to constantly look at ways to save energy."

It would cost about $2.5 million to tackle all 880 intersections at once, Blount said, but he anticipates the savings in electric bills will leave enough cash over time to change the remainder without additional funding from Commissioners Court.

Precinct 2 Commissioner Jack Morman praised the effort. The intersection of Uvalde at Wallisville in Morman's precinct was one of four test intersections converted to LED last year.

"This program is a great program," Morman said. "It's one that makes great business sense and it's great for the environment. Certainly programs such as this are things we should be looking at everywhere."

Precinct 3 Commissioner Steve Radack, whose precinct also included an intersection used to test LED signals, agreed.

"You're going to start saving money on the operation and let's face reality, if you have lights that burn out more frequently, that can create a traffic hazard," he said.

The city of Houston in 2007 began a $1 million effort to replace 300 traffic signals with LEDs downtown, in Midtown and near the Texas Medical Center, Public Works Department spokesman Gary Norman said. That program expanded into a $16 million, 1,700-signal project citywide; today, Norman said just 398 signals remain to be converted. The city has received a grant to help complete the work, he said, which will begin this spring and take about a year.

The spread of LED traffic signals began a decade ago, but sped up in 2006, when the Department of Energy mandated that new or replaced signal systems meet more stringent energy requirements, said Siva Narla, senior director of transportation technology at the Institute of Transportation Engineers.

ITE's position, Narla said, is that "these are beneficial, these are more energy-efficient and, as a community, LEDs are the way to go."

LEDs are not without without flaws, Blount said. They draw so little power that, unlike incandescent bulbs, they will not trigger a computer alert when they die. The lights, however, dim slowly, he said, leaving technicians time to monitor them as they fade.

Engineers at the county now are designing a battery backup for use at intersections equipped with LEDs to prevent the traffic signals from going dark during power outages. Incandescent lights draw too much power to make that practical, Blount said. Keeping signals running will improve safety and save money, he said, because it will keep crews from having to go out and manually reset lights after outages.

mike.morris@chron.com