I-35 expansion: TxDOT project takes shape in South Austin

Yahoo

12-06-2025

The Brief
The I-35 Capital Expressway South Project is starting to take shape in South Austin
The project includes a long, elevated section of roadway to speed traffic through that part of town
The entire project is targeted to be completed in late 2028 or early 2029
AUSTIN, Texas - A multi-million-dollar construction project is taking shape in South Austin.
The I-35 Capital Expressway South Project includes a long, elevated section of roadway to speed traffic through that part of town.
What they're saying
The massive concrete pillars that are rising above I-35 are part of the Capital Expressway South Project. The T-shaped monoliths will hold up an elevated roadway between Ben White and Slaughter Lane.
"There's about 95 to 100 of those when we're done," said Willie Semora, TxDOT's Director of Construction for the Austin District.
The caps, according to Semora, are almost 100' wide.
"They were pretty massive, really, in the grand scheme of anything I've ever built in my career," said Semora.
The $548 million project is being done in four phases. The new fast track in the middle of I-35 is the main feature. It will allow traffic to bypass Stassney Lane and William Cannon.
"So, everything is non-toll. So we're calling them managed lanes. The intention is HOV or to really push the transit message and let folks that are, you know, multiple people in a vehicle, buses, those kinds of things use those lanes to ultimately reduce capacity or reduce congestion and increase capacity on the rest of 35. But nothing's tolled when we're finished," said Semora.
Multiple heavy lifting cranes are needed to assemble the elevated roadway. There are almost 79 tons of prestressed girders. That's more than 157 million pounds, and, according to TxDOT, the equivalent of eight Eiffel Towers and 700 fully-loaded railroad cars.
"It takes two cranes to pick up one set of cap forms. Right. So, everything is bigger. Everything is heavier. And to do it safely, everything requires more resources," said Semora.
Advanced planning was done to avoid supply line issues.
"We use what we call material on hand. And so they may buy the steel we need to put in those columns two years before we build it. But we're really trying to plan ahead to keep that. From impacting us long term," said Semora.
The main contractor for the project, Flour Corporation, has even built their own concrete plant.
"We didn't want to tax the resources of the rest of Austin, right? There's a lot of construction going on everywhere. People are building buildings, doing utility work. So, with the amount of concrete that we're putting out there, our contractor brought their own plant and made it themselves," said Semora.
Big changes are also being made on the ground. The most notable involves addressing a steep slope around Onion Creek.
"We flattened that dip out and that's going to help with getting trucks up and down the hill, start time. A lot of traffic is a truck sitting in lane, and he can't get going up that hill. So, we fixed some of that," said Semora.
Part of the fix will require a big detour this weekend at Stassney Lane. The bridge will be closed, requiring a long U-turn.
The entire project is targeted to be completed in late 2028 or early 2029.
The Source
Information from interviews conducted by FOX 7 Austin's Rudy Koski