Noise concerns amplify as I-35 expansion in Central Austin nears

A major road project on the brink of charging through Austin will resonate in more ways than one.

By Nathan Bernier, KUTAugust 29, 2023 10:15 am, ,

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Now that the expansion of I-35 through Central Austin has cleared a final bureaucratic hurdle, the city can expect the project to resonate in more ways than one.

Noise from heavy machinery will rumble day and night after construction starts next year. Once completed, the enlarged highway will hold more vehicles, turning up the volume of growling engines, exhaust systems and tires slapping pavement.

The noise will likely be dampened along some sections of the interstate. Lowering the main lanes for much of the distance from Oltorf Street to Airport Boulevard will shift the source of sound into a highway trench. If the city and the University of Texas cough up millions to cover the excavated interstate, noise would be muffled even more.


A rendering showing what I-35 could look like after construction. The main lanes have been lowered and the MLK Jr Boulevard bridge over I-35 has been widened.

But adding two lanes in each direction from Ben White Boulevard to U.S. 290 East will crank up the cacophony in several areas, according to TxDOT’s own environmental analysis. And the construction of I-35 in Central Austin will rumble for 10 years while residents endure the sonic impact.

The overnight hours could be especially irritating. TxDOT prefers to do construction at night because daytime road closures cause traffic jams. Local noise rules would prohibit that overnight clanging, but the city’s sound ordinances don’t apply to I-35, because it’s owned by the state.

Besides highway construction, Texas plans to dig large underground tunnels as part of a new drainage system. The three drilling sites — located south of Cesar Chavez between Tillery Street and Springdale Road, along the I-35 northbound frontage road between Clermont Avenue and Flores Street and along the I-35 southbound frontage road north of East MLK Jr. Boulevard — will have 24-hour truck traffic hauling away rocks and debris set loose by underground tunneling machines.

Noise walls

TxDOT is taking some measures to reduce the noise, but the state’s power to control sound is limited by the laws of physics.

Ten permanent noise barriers are planned along the 8-mile project. Under TxDOT’s rules — for a location to qualify for a barrier — traffic noise has to exceed a certain level and the sound wall has to provide a minimum amount of noise reduction.

One of the locations that could get a noise barrier is the Festival Beach Community Garden and Food Forest — a gardening oasis just a stone’s throw from the I-35 frontage road near the north shore of Lady Bird Lake.

Patricia Lim / KUT

A volunteer spreads compost at the Festival Beach Food Forest in April.

The Food Forest was a grassroots initiative. In 2014, the City Council gave a group of volunteers permission to cultivate an empty lot. Now, anyone can go forage for their own food or medicinal plants. Eventually, the Food Forest will grow to fill the entire 2-acre lot.

But the nearby highway is growing, too. Volunteers are worried about the environmental impacts, including construction dust settling on plants people eat, stormwater runoff and increased traffic noise.

TXDOT says an 18-foot-high noise barrier stretching 480 feet along Waller Street will reduce traffic sounds by 7 decibels (dB). For comparison, a 10 dB reduction would sound half as loud.

“It’s a noticeable [reduction in sound]. It would be quieter than it is now,” TxDOT sound expert Ray Umscheid told a group of volunteers seated under the shade of a tree during a recent meeting at the Food Forest.


A green line shows where TxDOT is proposing to build an 18-foot-tall noise barrier that would stretch a total of 480 feet. TxDOT still has to do an analysis to make sure the wall can be constructed in that location. And the City of Austin would have to approve it.

Some volunteers asked if TxDOT could use trees or other plants to achieve a similar noise reduction. Umscheid said that would require 150 feet of dense evergreen vegetation.

“It’s pretty difficult, especially in Texas, to get evergreens,” he said.

The highway builders didn’t leave the gardening enthusiasts feeling assured.

“I’m personally conflicted about it,” said Angie Holliday, a longtime volunteer with the Festival Beach Food Forest who works for the related nonprofit Fruitful Commons.

Holliday says less noise is better, but she’s worried about the wall restricting air flow.

“We have concerns about the aesthetics. We’d love to have murals, like local art up there to make it enjoyable to be here,” she said.

TxDOT has vowed to meet with volunteers and others to discuss the appearance of the wall and other design considerations.

Meanwhile, just a few steps away from the Food Forest, a tunnel boring site will bring 24-hour noise and light, increased truck traffic and construction-related air pollution.

TxDOT didn’t mention the tunnel boring site at the meeting with Food Forest volunteers. The volunteers weren’t fully aware of the site until a few days ago.

Nathan Bernier / KUT

Some residents along MoPac say noise barriers haven't done much to turn down the volume of traffic in their homes.

How well do noise barriers work?

Noise barriers have become a common site along highways, railways and other busy thoroughfares. States are collectively building about 120 miles of noise barriers per year at a cost of more than $300 million, according to the latest data from the Federal Highway Administration.

TxDOT says noise barriers in Texas should blend in with the surrounding environment, not block traffic and not cost too much.

“Noise barriers are meant to be a positive addition to a neighborhood and are normally well received,” the state agency says in a brochure.

But noise barriers aren’t always the cure people expect.

One woman who lived next to MoPac fought for more than two decades to have noise barriers put up behind her backyard. Retired high school teacher Frances Allen finally got the noise wall when the Central Texas Regional Mobility Authority built the tolled lanes on MoPac.

Allen wasn’t impressed.

“She was just shocked that it didn’t abate the sound as we had hoped,” said Allen’s daughter, Kathy Sederholm, who lives in the house now. Allen died in 2019.

“It probably depends on where you are and how high the wall goes up at your property. But for us there was not a remarkable difference,” Sederholm said.

A few houses down the street, Robin Gann said she’s started sleeping in the bedroom farthest away from MoPac because of the noise.

“That wall made no difference at all,” said Gann, who’s lived in the house for 32 years. “I can hear everything.”

Both homes are uphill from MoPac, so the sound generated by the highway can still reach over the 10-foot wall.


Noise barriers have to be tall enough to block sound. This was the scene when the sound walls were being constructed along MoPac in 2016.

Noise barriers are usually effective at toning down the traffic racket if they’re well designed and constructed, said Jorge Arenas, a professor at the University Austral of Chile’s Institute of Acoustics.

But noise barriers have downsides for residents.

“They complained, for example, about the loss of sunlight,” Arenas said. “The restriction of view. The restricted access to the other side. The loss of air circulation.”

That reduction in air circulation can mean less pollution from traffic reaches areas right next to the highway.

“It does reduce pollution say about [500 feet] from the freeway,” said Akula Venkatram, a professor of mechanical engineering at the University of California Riverside. “All it does is reduce the high concentration. It doesn’t get rid of the air pollution.”

But Venkatram said a highway expansion would make pollution worse, anyway.

“The reduction in air pollution might be more than compensated by the increase in emissions,” he said.

“I wouldn’t recommend anyone work next to a freeway, because you’re going to be exposed to air pollutants all the time,” Venkatram said. “I’m always shocked when they’re building apartments next to highways with the windows facing the highway.”


TxDOT plans to construct temporary noise barriers to shield residents from construction sounds. The barrier is indicated by the dotted orange line next to the Swede Hill neighborhood.

So what’s next?

TxDOT will pay for the noise barriers, but the property owners must approve construction.

For the barrier next to the Festival Beach Community Garden and Food Forest, the owner is the City of Austin. The decision on whether to build it will ultimately be made by Parks and Recreation Director Kimberly McNeeley.

If all goes according to TxDOT’s plan, the noise barrier at Festival Beach would be installed within two to three years.

Here’s the full list of noise barriers TxDOT is planning to build. In some cases, the barriers are broken into parts so they’re not blocking streets or sidewalks.

1. Cherrywood: a 2,572-foot-long and 20-foot-tall barrier on the east side of I-35 between 38 1/2 Street and Edgewood Avenue

2. Aura University Park Apartments: a barrier 435-feet long and 20-feet high on the west side of I-35 between 32nd Street and Duncan Lane

3. Swede Hill Lofts: a sound wall 167-feet long and 16-feet tall on the east side of I-35 between 13th Street and 14th Street

4. AMLI Eastside Apartments: A 207-foot long and 20-foot tall noise barrier on the east side of I-35 between Ninth and 10th streets

5. Residences at Saltillo Apartments: A barrier 236-feet long and 20-feet tall on the east side of I-35 between Fourth and Fifth streets

6. 3Waller Apartments: A 277-foot barrier that’s 18-feet tall on the west side of I-35 between Third and Fourth streets

7. Festival Beach Community Garden and Food Forest: A 480-foot barrier 18-feet high on the east side of I-35 just north of Lady Bird Lake

8. Berkshire Riverview Apartments: A 718-foot barrier 20-feet tall on the east side of I-35 north of Riverside Drive

9. Motel 6: A 133-foot barrier that’s 8-feet tall on the east side of I-35 just north of Royal Hill Drive

10. Grace Woods Apartments: A 625-foot barrier 20-feet tall on the east side of I-35 just north of Woodward Street

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