Austin must decide within just a few weeks whether to commit hundreds of millions of dollars to installing support structures on Interstate 35, or give up the chance to build parks over the highway.
The City Council has until May 31 to choose locations for the foundational elements that would hold up large decks — or caps — over the highway.
Without those support structures, any caps over the soon-to-be-lowered highway — and the parks, plazas, buildings and public spaces envisioned for them — would be physically impossible. The chance to add support structures wouldn't reappear for at least 50 years.
The load-bearing infrastructure doesn't come cheap. The cost of just the foundational elements is estimated at $284 million.
The full buildout of the support structures, the decks and all the amenities, including splash pads and amphitheaters, is estimated to hit $1.4 billion. The price tag could double if the city waits too long to pay for caps, the city's top transportation official warned at a Tuesday briefing.
Those construction costs don't include the yearly expenses of keeping the infrastructure in good repair and running the niceties on top of the highway decks. Annual operations and maintenance is estimated at $47 million.
As the clock ticks toward this high-stakes decision, the mayor and 10-member City Council are already confronting a serious and growing cash crunch.
Budget officials alerted council members Tuesday that Austin is $5.7 million short of the $1.42 billion planned to be spent on city government operations in 2025. The lack of cash is largely because of lower than expected sales tax collections.
Without hacking off significant pieces of city government or getting approval from voters to increase property taxes, the budget deficit will only grow. By 2030, city officials project Austin's annual budget would be $80 million in the red.
Paying for deck infrastructure by issuing bonds would eat into Austin's borrowing capacity, leaving less room for roads, parks, affordable housing and a bevy of other priorities being considered for a 2026 bond election. Bonds are a type of loan where investors lend money to government agencies with a promise the cash will be paid back with interest.
The capping project is only being considered because the Texas Department of Transportation (TxDOT) is sinking the main lanes of I-35 below ground level from Holly Street to Airport Boulevard. The lowered lanes are part of a historic expansion that includes adding two high-occupancy vehicle lanes through the busiest part of the interstate in Austin.
The I-35 Capital Express Central project will add 32-miles of lanes from Ben White Boulevard to U.S. 290 East, widening the highway that opened in 1962 along a historic racial segregation line known as East Avenue. For some members of the council, the caps are a once-in-a-lifetime opportunity to stitch together pieces of the city divided for decades.
"Everything we do, there's some implication that ties back to city-sanctioned segregation that split the city in half," Council Member Natasha Harper-Madison said.
Other council members were excited about the economic development acres of prime downtown real estate out of thin air could attract, and even help pay for the project.
"It's just such a tremendous opportunity," Council Member Chito Vela said. "If you're bullish on Austin's future, you support the caps."
Not all council members were so enthusiastic. District 6's Krista Laine said Austin had to foot a bigger share of the bill than cities with similar projects in other states, which she cautioned should be a sign that the "tradeoffs are too great."
"We will be foreclosing our ability to spend on other critical needs all over the city at a time when our residents will need Austin to be able to have funds available for these emergent needs," Laine said. "We have to preserve the flexibility for our local community."
Even if the council approves the support structures, it's still unclear how the city would pay for them.
The only firm commitment so far is a low-interest $41 million state infrastructure loan from TxDOT.
A much-needed $105 million federal grant awarded for the Cesar Chavez to Fourth Street cap was frozen for review by the Trump administration. City officials expect to know in May whether they'll get the money.
Amid the uncertainty, one major player has already locked in its plans. The University of Texas System voted in December to spend $106 million on support structures for its portion of I-35 from Dean Keeton to 15th Street. That stretch could eventually add 13 acres and bridge UT athletic facilities on both sides of the highway.
Next up, the Austin City Council is scheduled to meet May 6 for a deeper conversation about how much the city can borrow.
The big vote is expected May 22 when the council will also decide whether to pay for any decks now, locking in the price tag before the costs go up.
