I-35 frontage roads would be on the same side of the interstate under TxDOT’s new plans

The Texas Department of Transportation’s latest proposal to expand Interstate 35 includes a plan to run the northbound and southbound frontage roads directly next to each other on the same side of the highway between Cesar Chavez and Dean Keeton streets.

The frontage roads would be at ground level with the interstate lowered and possibly covered if the city of Austin can come up with an estimated $700 million to $800 million to pay for the coverings, or caps as they’re called.

“The northbound frontage road will come across Holly, marry up with the southbound and will be in a boulevard-style setting,” TxDOT Austin district engineer Tucker Ferguson said at an unveiling of the new schematics.

Both frontage roads would cross over the lowered main lanes at 15th Street and run along the east side of I-35 to Dean Keeton Street. At that point, the southbound frontage road would pass back over to the west side of the interstate.

TxDOT disclosed the changes Tuesday as part of Build Alternative 3 – the name given to one of two remaining options that would increase the highway’s capacity by adding two HOV lanes in each direction. The HOV lanes would be off limits to single-occupancy vehicles.

Other changes to Build Alternative 3 include new bicycle and pedestrian crossings at 51st Street, Airport Boulevard, 41st Street, Martin Luther King Jr. Boulevard, 15th Street, Fourth Street, Third Street and Woodland Avenue.

The new proposal also includes something called a single-point urban interchange at Riverside Drive. A SPUI (pronounced “spooey”) is a relatively new type of high-volume intersection design that uses a single traffic signal. TxDOT says it chose the SPUI configuration to accommodate a light-rail line planned along Riverside.

Build Alternative 3 would lower the I-35 main lanes for most of the project boundaries between Ben White and U.S. Highway 290 East, meaning the interstate would pass underneath streets like Airport Boulevard, Holly Street and Woodland Avenue.

Reaction from community groups that had been pushing for changes to the original plans were mixed.

“The (revision) reflects progress towards our common goals,” Reconnect Austin co-founder Heyden Black Walker said in a statement. The group has pushed for years to bury I-35 through the urban core. “Additional input on today’s significant modifications will help further refine this project.”

Rethink35, an organization advocating for I-35 to be removed and replaced with an urban boulevard, was less amenable to the revisions.

“TxDOT’s new I-35 plans are still a major highway expansion that will waste $5 billion to worsen traffic and contribute to the climate crisis,” Rethink35’s Adam Greenfield said. “The plans are rotten to the core and should be completely thrown out.”

Meanwhile, a group of neighborhood associations immediately north of downtown said TxDOT’s efforts to improve the design neglected their stretch of the interstate.

“It’s feeling like we’re not being considered as part of the urban core,” said Brendan Wittstruck, chair of the North Central I-35 Neighborhood Coalition, which represents 12 neighborhood groups along the interstate between Martin Luther King Jr. Boulevard and U.S. 290 East/Koenig Lane.

“We’re seeing a lot of focus and investment on improving the downtown, and it’s coming as part of a project that is – in its current form – still creating a bigger division in central neighborhoods,” he said.

You can view detailed schematics of the revised I-35 widening plans on the project’s website. TxDOT will choose a final proposal and return to the public in about a year to get final comments. The agency hopes to start construction in late 2025.

This story was produced as part of the Austin Monitor’s reporting partnership with KUT.

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