Two major parts of the Texas Department of Transportation’s $4.5 billion I-35 Capital Express Central project will pick up speed in Austin next year.
The project’s Drainage Tunnel and Pump Station segment, which began in mid-2025, will receive its two Herrenknecht Tunnel Boring Machines in 2026, according to a report from Spectrum News 1. Those TBMs will create 6.5 miles of 22-foot diameter tunnels between Airport Boulevard and Holly Street; and along Cesar Chavez Street, from I-35 to US 183.
Other improvements include access shafts added along I-35 for maintenance and a pump station for better stormwater management. The contractor for the drainage tunnel is SAK/Shea JV and the contractor for the pump station is Webber Waterworks.
Work on the drainage tunnel and pump station is expected to wrap up in 2029, weather permitting.
A separate portion of the I-35 Capital Express Central project, the Lady Bird Lake segment, will begin work on the Lady Bird Lake Bridge in late 2026. The project will reconstruct the bridge, add two high-occupancy managed lanes in both directions along an 8-mile corridor of I-35, and build a single-point urban interchange at Riverside Drive. A pedestrian-only bridge will be built at Woodland Avenue and bike and pedestrian paths will be added along I-35.
Balfour Beatty Construction won the Lady Bird Lake segment contract. Work began in early 2025 and is expected to finish in 2033, weather permitting.
The overarching goal of the six-part I-35 Capital Express Central project is to improve traffic flow on I-35 in Austin, one of the most congested highway segments in Texas, according to TxDOT. The other four parts of the Central project will address:
- Martin Luther King Jr. Boulevard Bridge: started in October 2024, anticipated completion in 2026
- CapMetro Bridges: Anticipated start in early 2026, anticipated completion in 2033
- University Segment (US 290 East to Martin Luther King Jr. Boulevard): anticipated start in mid-2026, anticipated completion in 2033
- Downtown Segment (Martin Luther King Jr. Boulevard to Holly Street): anticipated start in late 2026, anticipated completion in 2033
The six-part $4.5 billion I-35 Capital Express Central project is just one of seven segments that fall under TxDOT’s MyMobility35 project, a massive plan to update 79 miles of I-35 in Williamson, Travis and Hays counties.
The price tag on the three I-35 Capital Express projects alone – Capital Express North, Central, and South – is estimated at around $5.7 billion. Several legs of the MyMobility35 project are still being studied and planned.
