Texas set to widen heavily traveled Interstate through downtown Austin

Interstate 35, which cuts through the heart of downtown Austin, Texas, is set to undergo a major expansion that state transportation officials say is necessary to bring relief to one of the state’s most clogged highways that will only get more congested as the population continues to grow.

Austin has seen its population double every 20 to 25 years, and last year it broke into the top 10 largest cities in the nation for the first time.

To keep pace with the traffic that’s come along with new residents, the Texas Department of Transportation has launched a $5 billion, four-lane expansion of I-35 through the downtown area, the largest expansion since the highway opened in 1962. It’s the third part of the three-pronged I-35 Capital Express Program that includes similar but less complicated expansions on the north and south sides of the city.

Opponents, who filed a lawsuit seeking to block the central Capital Express project in January, warn the expansion will worsen I-35’s historic role as the city’s racial dividing line. The city of Austin has crafted a plan to try to diminish the barrier with a series of bridges and caps covering the highway, but it remains uncertain whether the city can meet the roughly $900 million price tag.

The federal lawsuit also warns of environmental harms from construction and a widened highway, saying the state and U.S. Department of Transportation failed to follow National Environmental Policy Act, and point to an existing state highway that swings around the city as a better alternative.

The Austin project is part of the state’s larger Mobility35 program, which aims to make improvements to 79 miles of I-35 through four counties. The Central Texas highway — dubbed the “Main Street of Texas” — is a major freight corridor and feeling the impact of increased population and commercial activity, Marc Williams, Texas Department of Transportation’s director, said at a recent local 2024 transportation summit.

“With that economic growth comes a demand for more transportation infrastructure,” Williams said. “The work will never conclude on Interstate 35 between Austin and San Antonio, I can say that pretty definitively.”

TxDOT currently has nearly $40 billion worth of construction projects on tap, compared to California’s $14 billion, according to Williams. The department’s 10-year transportation plan features another $100 billion worth of projects. While the 2021 Infrastructure Investment and Jobs Act brought support, inflation has eaten away at much of the federal funds, he said. TxDOT relies heavily on its own state funds to support construction, including a piece of the oil and gas surplus and sales taxes that voters approved in ballot measures starting in 2014.

Williams said the Lone Star state recently topped 30 million and sees 1,300 new residents arrive daily, with the San Antonio to Austin region projected to grow from 5.2 million to 8.3 million people by 2050. TxDOT’s duty is to “really to keep pace,” Williams said.

The I-35 central expansion will add four high occupancy vehicle lanes through downtown, which the state says is needed to ease congestion and increase safety.

But research shows that highways typically reach capacity again within three to five years after an expansion, said Kevin DeGood, director of infrastructure policy at the progressive think tank Center for American Progress.

“Travel demand is not a fixed quantity,” DeGood said. “The worse the congestion is, the faster that road is going to fill up.”

Houston’s Katy I-10 Freeway is a good example, he said. The road has been widened “multiple times” — at its widest, it’s 26 lanes across — while overall delay and performance has gotten worse,” he said. “The idea that a highway expansion is going to provide long-term congestion relief is just false.”

The only tool that’s shown to actually reduce traffic jams, DeGood added, are variably priced toll lanes. Texas lawmakers have essentially banned any new toll roads or lanes.

TxDOT has already broken ground on the smaller two projects that make up the Capital Express program. The north project, which will add one managed lane in each direction, carries a $600 million price tag. The south project, which features two managed lanes in each direction, is estimated to cost $550 million.

The central portion will include eight miles across downtown Austin at a cost of $4.9 billion. The Texas Transportation Commission, a five-member board that oversees TxDOT and is one of the state’s largest bond issuers, approved $4.98 billion in 2020 and the Capital Area Metropolitan Planning Organization committed $633 million.

Improvements include removing existing upper decks of the highway, lowering the roadway, reconstructing bridges and adding two high-occupancy vehicle lanes in each direction.

“We have this massive highway cutting through the heart of the city and through the most valuable land in the state,” said Miriam Schoenfield, a board member with ReThink 35, one of several plaintiffs that filed the Jan. 26 lawsuit in federal court to block the project. “Expanding highways through dense urban areas doesn’t work. It doesn’t alleviate congestion and in fact often makes congestion worse because of induced demand,” she said. “It also means a ton of harms for the local community.”

In a statement responding to the lawsuit, Williams said the state “carefully followed and even exceeded the environmental and legal requirements to advance this project.”

The Austin area is set to see $10 billion of economic activity in the next 30 years, and improvements to I-35 are “critical,” he said. “The traffic demand is here and will continue to grow as more people move to the Austin area to take advantage of the booming job market and quality of life that Central Texas offers.”

Neither the state, U.S. DOT or Federal Highways Administration have filed responses yet to the lawsuit.

The Austin City Council has also registered its opposition to the project with a pair of resolutions, most recently in October asking TxDOT and the Capital Area Metropolitan Planning Organization, to pause the project and look closer at the environmental ramifications. TxDOT denied the request.

Assuming that the project is going forward, the city has crafted a “cap and stitch” plan called Our Future 35 to try to mitigate the interstate’s physical barrier by building a series of caps, or covers, and stitches, or widened bridges, along with public spaces and parks.

The state has included some of the features on its renderings, but has told the city it needs to come up with the money. Funding options include bonds — which would require a bond election — as well as tax increment financing, federals grants and a Transportation Infrastructure Finance and Innovation Act loan.

“City staff are discussing funding options holistically and continue to touch base with City Council members to discuss various funding scenarios,” a spokesperson for the Austin Transportation and Public Works Department said in an email.