The Texas Public Interest Research Group (TexPIRG), Environment Texas, and the Rethink35 campaign has filed a lawsuit against the Texas Department of Transportation (TxDOT) over TxDOT's plans to spend over $1 billion to expand I-35 to 19+ lanes in the north and south of the Austin area.

The lawsuit alleges that TxDOT is "violating the law" by splitting its I-35 project into separate parts to avoid a more rigorous environmental review process and public engagement of one larger project.

"By splitting its I-35 project into separate parts, TxDOT is clearly violating the law," says TexPIRG Environment Campaigns Director Matt Casale. "For such a major highway project, TxDOT should be undertaking the most rigorous environmental review process, as well as giving the public much more opportunity to meaningfully participate in the conversation."

The groups say that by splitting TxDOT's overall I-35 Capital Express expansion project into three sub-projects, the I-35 Capital Express North (SH-45 N to US-290 E), South (SH-71/Ben White Blvd to SH-45 SE), and Central (US-290 E to SH-71/Ben White Blvd) projects, TxDOT is "falsely claiming" that these three stretches of I-35 are "independent utilities."

Group leaders said in a press release Monday that TxDOT's "Finding Of No Significant Impact (FONSI)" for I-35 South and I-35 North comes despite its plans to expand the North section from 12 to 20 lanes and the South section from 14 to 19 lanes. Rethink35 is challenging the proposed expansion.

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"Countless examples, including the notorious Katy Freeway expansion in Houston, have shown that widening highways worsens congestion by encouraging more driving," said Adam Greenfield, Rethink35's Executive Director. "The public has a right to consider options for I-35 that will actually work, including alternatives to driving, not just expansion."

Greenfield said this project is also an equity issue. He believes widening freeways worsen serious and fatal traffic crashes, air pollution, noise, and carbon emissions, that will impact low-income communities and communities of color.

According to TxDOT, the I-35 Capital Express North and South project is needed "due to population and employment growth, which have caused increased congestion in the area." The project will reconstruct bridges, add pedestrian and bicycle paths, and make additional safety and mobility improvements. Construction is anticipated to start in 2022.

The proposed improvements for the I-35 Capital Express Central project include removing the existing I-35 decks, lowering the roadway, and adding two non-tolled high-occupancy vehicle-managed lanes in each direction along I-35 from US 290 East to SH 71/Ben White Blvd. Construction on this project is scheduled to begin in late 2025.

TxDOT said on its I-35 Capital Express Central page that its "undertaking the most rigorous level of environmental analysis with the development of an Environmental Impact Statement for the I-35 Captial Express Central project." The timeline of the environmental study and design is scheduled from 2020-2023.

The three groups say the lawsuit comes as the public is turning against new highways and highway expansion according to TexPIRG's annual Highway Boondoggles report. There are also concerns that more people in the line of the construction of the project will be displaced.

"The game is up on highway expansions and the devastating impacts they've had for too long," said Greenfield. "We look forward to a favorable verdict in court over TxDOT's regressive plans for I-35."

TxDOT spokeswoman Diann Hodges told CBS Austin that the agency does not comment on pending litigation.