Q: Aug. 1 marked the five-year anniversary of the fatal collapse of the I-35 bridge in Minnesota. That bridge has been replaced with an improved design that is not 'fracture critical' and is considered to be a 'smart' bridge featuring 26 accelerometers that continuously monitor vibrations. It also has the first application of LED lighting. Are there any plans for LED highway lights in Pennsylvania in the near future?
— Dale Heffelfinger, Whitehall Township
A: LED lighting is the best and brightest of the energy-efficient lighting technologies coming down the road — one of the few new models, really, since artificial illumination sprung from the Edison assembly line more than 130 years ago.
Light Emitting Diodes offer the smoothest ride of any lighting technology for energy efficiency and product longevity, though sticker shock is a factor. As with most showroom-floor technologies, prices are expected to drift downhill as the market grows and manufacturing efficiencies are realized.
LEDs increasingly are taking the on-ramp to the household lighting market, possibly at the expense of compact fluorescent bulbs or CFLs, which have barely gotten off the road surface themselves. And though LED prices already are declining, most of the models tested recently by Consumer Reports cost the magazine between $25 and $60 each — a steep price premium CFLs, and especially over dirt-road-cheap incandescents. However, the magazine still waved the checkered flag for LEDs in the end, concluding that the energy-cost savings over the projected 23-year life of LEDs more than covered the added upfront cost.
Back on street-lighting road, many cities including Boston, Seattle and Pittsburgh are putting LED conversions into gear, hoping to save truckloads of money over time.
In our region, Lehigh County officials are considering adding LED lighting on the interchange ramps at routes 22 and 309, possibly beginning early next year. General Services Director Glenn Solt said officials have been working on the proposal with PennDOT, and with PPL Corp., which might be able to provide energy-saver rebates to the county in connection with the upgrade.
"We hope to use a combination of liquid fuels funds [from gasoline taxes] and energy rebates from PPL" to help finance the pilot project, Solt said. Preliminary estimates peg the cost at just under $100,000 to change out the 89 high-pressure sodium bulbs at the interchange; if this proves a smooth road, the Airport Road interchange could follow, with its 120 lights, for about $132,000, according to rough estimates.
If the plan stays on the road, the two Valley interchanges could be the first in the state to get LEDs. "Currently there are no interchanges that PennDOT is involved in that are illuminated with LED lighting," PennDOT spokesman Ron Young wrote in an email.
Solt said he passes an interchange with LEDs on regular family trips to Virginia, on Interstate 83 near I-695, and has been impressed by the lighting quality. "The difference is remarkable," he said, the LEDs producing "a much brighter, cleaner, crisper light" than standard-model bulbs, while power consumption is halved, and maintenance and overall life-cycle costs also are greatly reduced, he said.
Not everyone is enamored of this newest model in lighting technology. A Carnegie Mellon University study commissioned by the city of Pittsburgh found that "glare is an issue with LED street lighting," and that some manufacturers and other proponents stress energy savings "to the exclusion of visual-quality issues."
It's true that LEDs contain no mercury or other toxic chemicals, but manufacturing the lights "is energy intensive and does include dangerous chemicals in the manufacture of its semiconductors," the report states. Still, LEDs appear to be "the better [environmental] choice" among predominant lighting technologies, the study concludes.
If glare is a problem, LEDs might worsen the experience for glare-sensitive motorists, including many older drivers, though Solt said he notices no such problem in Virginia. "I'm not sure what you mean by older, but I think I can somewhat relate; my eyes aren't what they used to be," said Solt, 57.
In addition, he said, worries about glare or other problems with LEDs could retrace the course of initial consumer reaction to CFLs, many of which cast the familiar harsh, blue-tinted light common to fluorescent lighting in offices. But newer CFLs are offered in "warmer" shades closer to what consumers associate with "soft white" incandescent bulbs, and LEDs can produce different degrees of light "color" as well.
Some manufacturers contend that LEDs actually reduce glare, and though Carnegie Mellon noted that comparisons tend to focus on high-pressure sodium bulbs, which provide the familiar yellowish glow that bathes many streets, highways, parking lots and other outdoor-lighting venues, the U.S. Department of Energy posts side-by-side photos in which metal-halide glare seems worse than LEDs.
Manufacturer Osram Opto Semiconductors of Northville, Mich. boasts that LEDs offer "long life, directional light, uniform brightness and illumination," also touting the technology's green credentials, "as [LEDs] contain no mercury or lead, which means no hazardous materials in local landfills. LEDs in a properly designed luminaire are also dark-sky friendly, eliminating stray light and reducing overall light pollution."
In a recent op-ed in the Boston Globe, Edward Smalley, a Seattle street-lighting official and director of the Energy Department's Municipal Solid-State Street Lighting Consortium, wrote that cash-strapped municipalities could save millions each year through LED street-light conversions.
Illuminating the country's estimated 26 million street lights uses as much power as 1.9 million homes, and generating all that electricity creates the greenhouse gas emissions of 2.6 million cars, Smalley wrote.
As someone who, at 61, surely is considered an older driver by many motorists, I'd gladly put up with some extra glare, assuming LEDs produce any, in exchange for the cost savings and smaller environmental tire-print that ride as passengers with LEDs.
Carnegie Mellon's objective study prompts me to ease off on the accelerator, but at this point in the journey, LEDs seem a race-winning technology overall, with some speed bumps, but no immovable barriers before them. The Lehigh County pilot project could help answer any lingering questions about LED street lighting.
Road Warrior appears Mondays and Fridays, and the Warrior blogs at mcall.com. Email questions about roadways, traffic and transportation, with your name and the municipality where you live, to firstname.lastname@example.org, or write to Road Warrior, Box 1260, Allentown, PA 18105-1260.