Portsmouth I-95 sound walls: When they're coming, how much noise will be reduced

PORTSMOUTH — Construction on two long-anticipated sound wall projects aimed at reducing noise from Interstate 95 in city neighborhoods could begin as soon as the summer of 2024.

Sam Newsom, project manager for New Hampshire Department of Transportation’s Bureau of Turnpikes, estimated the sound walls could be completed in late spring 2025, as well as a related privacy fence.

Newsom told a group of residents gathered Wednesday night in City Hall the estimated cost is between $15 million and $16 million.

The project calls for installing about 2,400 feet of sound wall near the Pannaway Manor neighborhood, running “along the I-95 southbound corridor,” he said.

The project also calls for building an approximately 3,400 feet sound wall “in the Rockingham Avenue/Edmund Avenue” neighborhood area along I-95, Newsome said.

The state will also install a privacy fence of roughly 3,000 feet “about 300 feet north of Woodbury Avenue,” along the New Franklin School area, he said. State officials acknowledged the privacy fence won’t reduce any of the noise coming from nearby I-95.

“The sound walls cost themselves $14 million to $15 million,” Newsom said, while the privacy fence price tag is estimated to come in at about $500,000.

Significant noise reduction expected

Jon Evans is the air and noise program manager of the state Department of Transportation's Bureau of Environment.

During Wednesday’s meeting, he said, “Everybody wants to know …what are these noise barriers going to do?”

He explained noise benefits are defined by the state as “anything (where) you receive a five decibel or more reduction in noise.”

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He added that five decibels is sound that’s noticeable to the human ear.

The state believes that the Pannaway Manor sound wall will provide “noise benefits between eight and 14 decibels,” Evans said.

“These barriers here are going to provide quite a bit of benefit,” Evans said.

That should provide noise reduction to about 70 homes in Pannaway Manor, he said.

Neighbors in the middle-class neighborhood of smaller homes have been advocating for a sound wall or sound barrier for as long as 30 years.

In the Rockingham Avenue/Edmund Avenue neighborhood, Evans reported “49 homes would receive at least a five decibel reduction or more.”

But he acknowledged there will be “some gaps” in the sound wall where overpasses cross I-95.

Privacy fence 'a visual barrier' only

The sound walls were designed to mitigate the traffic noise “that already exists,” Evans said, but also the noise created by the “anticipated extra traffic 20 years into the future.”

The privacy fence, Evans stressed, “is intended to provide a visual barrier.”

“It is not a noise mitigation measure, it’s more of a visual barrier, some additional visual protection for the school,” Evans said, referencing New Franklin School.

That portion of the city along I-95 did not meet the requirements for a sound wall, state officials said previously.

Phil Kendall is a senior transportation engineer from HNTB, which is working as a consultant for the state on the project.

The height of the sound walls range anywhere from about 10 feet to 25 feet, he said.

They will be made up of gray concrete panels, which are similar to ones being used along I-93 in Londonderry, he said.

Height of walls creates noise reduction

The height of the panels were designed “to provide the necessary noise reduction” needed, Kendall said.

Bill St. Laurent is a longtime Pannaway Manor resident.

“I probably live on the most outer part closest to the highway of any of the houses,” he told state officials during Wednesday’s meeting.

He worried aloud about ending up with a “15-foot or 20-foot” sound wall near his house.

“If you put a 20-foot fence in my backyard because I’m right near the edge of the highway, that’s like a prison wall, that’s huge,” he said. “You should be able to step this down for the neighborhood."

He acknowledged that he’s “been fighting to get a wall there” for many years, but added, “please don’t put a 20-foot fence in my backyard.”

State officials replied the amount of noise protection the sound walls offer comes from their size.

“If we were to reduce the height of the barrier … some of the neighborhood is going to lose benefits,” Evans said.

“There would be homes that are getting (noise reduction) benefits farther back that would no longer get benefits,” he said. “The higher the fence, the more protection it would provide.”

This article originally appeared on Portsmouth Herald: Portsmouth NH I-95 sound walls: Here's what residents can expect