Environment
7:57 am
Fri November 30, 2012

Lighting Memorial Bridge, Not The Night Sky

The DOT head of the Memorial Bridge project, Keith Cota, points out design features of the new bridge to a Portsmouth resident
The DOT head of the Memorial Bridge project, Keith Cota, points out design features of the new bridge to a Portsmouth resident
Credit Sam Evans-Brown / NHPR

Portsmouth has always been especially proud of its Memorial Bridge, and many residents are excited about the replacement. One group is so excited, they’re working to light the bridge up at night, just like many other iconic bridges around the country. But they’re hoping to do so in a way that’s got advocates for a dark night sky nodding in approval.

If you drive a little bit south on I-93, you know when you’ve hit Boston. Passing between cables of the Zakim Bridge – especially at night when they are lit in a ghostly blue – it’s how you know you’ve hit Beantown.

That’s not lost on Ben Porter of Portsmouth, as he pitches the lighting of the Memorial Bridge to the community."50 percent of the postcards sold in Quincy market feature the Zakim bridge," Porter tells Portsmouth residents assembled to see the proposed lighting plan, at the Portsmouth Public Library, "And if you go to other cities around the world, you’ll see these stunningly beautiful bridges that are an attraction for the nighttime viewers and an attraction for the cities that host those bridges."

When it’s completed at the beginning of next summer, the silvery green finish of the new Memorial Bridge, will be crisp and fresh, like a car fresh off the dealer’s lot. Porter and the other Seacoast residents involved in the volunteer, donor-funded effort to light the bridge want to show patina off at night, not like what was done with the old bridge.

"Take a look at what the old bridge looked like in the night-time," Porter says in front of a slide showing the old Memorial Bridge lit by a yellowish glow that splashes out beyond the edges of the bridge. "For the street-lighting, they lit the street, and a lot else."

That light spilling out around of the edges of street lamps, bothers a lot of people of the New Hampshire persuasion.

"I moved to Portsmouth in early 2002, and from where I lived, I could see the Milky way, it is now 2012, and the Milky Way is gone," says David Speltz, who is part of the New Hampshire chapter of International Dark Sky, a group that helps advise communities on how to reduce light pollution, "And it’s not gone because people designed it to go away, it’s gone because one-by-one, light-by-light they were added in a way that just began blotting out the sky. We can reverse that."

His group collaborated with the light designers for the Memorial Bridge. Thanks to their efforts, the design was switched, and lights that had been planted at the base of the bridge’s towers and pointed skyward, are now set to be placed at the top and pointed down.

"Standard design streetlights emit about five to ten percent of their light, straight off to Jupiter." Bob Gillette is another Dark Sky advocate, from Ossippee "This is the easiest environmental problem that I know of to solve. And not only easiest, but you save money in solving it. Simply by doing sensible lighting, street lights that put all of their light down on the ground."

Environmental problems tend to be tricky economic puzzles as well. It costs extra to pave with permeable pavement, to design rain gardens, or improve waste-water treatment. Renewable electricity generation is more expensive that fossil fuels, and still requires subsidies to compete.

But Dark Sky friendly lighting is just like those CFL bulbs that are everywhere now: a little bit more expensive up front, but with dramatic cost savings down the road.

"The sodium vapor lights need to be changed every four years. The LED lights go through a change cycle, roughly every 25 years," Ben Porter tells the assembled crowd.

And they use less electricity too. The lighting design committee estimates taxpayers will save about $20,000 because of the lights they recommend.

But it is just one bridge. Bob Gillette has worked with a lot of communities, trying to educate folks on how to reduce light pollution. He helped draft a law in New Hampshire that encourages towns to use Dark Sky compliant lighting, and requires lights that the state replaces to be down-lit whenever feasible. He sees the big picture.

"We all realize that by downlighting this bridge, we are not going to significantly reduce the amount of light pollution that Portsmouth emits," Gillette concedes, "but this is such an iconic structure. If the lighting is designed to protect dark skys, the symbolic importance is really very great here."

It’s white bread: everybody’s on board.

The only question left, if the community raises the $80,000  dollars to fund the project, someone will get to control what color the lights will be, which can be changed at the flick of a switch.

That’s got Portsmouth Resident Jan Marx worried. "They had in the paper, that one Green tower, and one white tower at Christmas," she laughs shaking her head, "I’d never give any money to that."

Marx still says she’ll donate for the lights, since -- hey -- it’s easy enough to complain and get the mayor to flick the switch back to white again.