Austin outlines funding costs, timeline for I-35 'Cap and Stitch' initiative

In a Tuesday work session, Austin City Council outlined some of the financial aspects of the proposed Our Future 35 plan, which envisions deck plazas poised to go on top of the Texas Department of Transportation's Interstate 35 expansion near downtown.

AUSTIN (KXAN) — In a Tuesday work session, Austin City Council outlined some of the financial aspects of the proposed Our Future 35 plan, which envisions deck plazas poised to go on top of the Texas Department of Transportation's Interstate 35 expansion near downtown.

City officials outlined Tuesday several sites where "caps" — or deck plazas that can support community and green spaces, pavilions, public art or cultural facilities — could exist over the lowered highway. Those include caps from Cesar Chavez to 4th streets; a cap from 4th to 7th streets; one over 11th and 12th streets; as well as a cap from 38th 1/2 Street to Airport Boulevard.

A map rendering also outlines possible locations for University of Texas at Austin-spearheaded caps.

Robert Goode, interim assistant city manager with the City of Austin, previewed some upcoming funding deadlines, should council pursue caps as part of the project.

• December 2023: $15 million committed to fund design for both roadway elements, tunnel and cap elements through 30%
• December 2024: An additional $19 million committed on top of the initial $15 million to fund 100% final design; the total design costs — excluding the amenities set to go on top of the deck plazas — amount to $34 million

To help cover the roadway support structures, officials noted those road elements will cost $165 million and are separate from that $34 million figure. Under current city estimates, the costs for both the roadway elements as well as the tunnels and caps amount to $509 million. That doesn't include the estimated costs of amenities on top of the deck plazas, which are projected to cost around $338 million.

Several funding timelines are available for the city to consider:

• Option 1: Fund requested caps and stitches in TxDOT's roadway construction contract; to begin in 2026
• Option 2: Fund requested caps in TxDOT's roadway construction contract via a change order; to begin in 2027
• Option 3: Fund requested caps in a separate TxDOT contract that would start after roadway construction is substantially complete; to begin in 2032
• Option 4: Fund requested caps in a new contract after TxDOT's roadway construction is completed. However, TxDOT doesn't want construction to occur on the roadway for 10 years after the expansion's substantial completion, so this option wouldn't begin work until 2042

The city is slated to hear back from the U.S. Department of Transportation on its $105 million cap and stitch grant application in February. From there, design work is set to finish in spring 2026, the same year that TxDOT is on track to begin roadway construction.

Some funding options available and under consideration include federal grants, public improvements bonds courtesy city debt, tax increment financing opportunities and the Transportation Infrastructure Finance and Innovation Act (TIFIA) Loan. During council's discussion, Mayor Kirk Watson said the TIFIA option could cover the entirety of the proposed caps and features a low interest rate and extensive timeframe to pay off the related debt.

Council signified interest in putting together that initial $15 million investment in December to cover 30% design and environmental work on the caps. From there, Goode said city staff will await federal updates on the grant application before revisiting the caps and prioritizing project components to include.