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.
Powered byBalfour 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.
