When will construction begin on TxDOT's I-35 Capital Express projects?

Two of the Texas Department of Transportation's three Interstate-35 express projects are on track to begin construction this year, officials said Monday. TxDOT's I-35 Capital Express program is a 28-mile trek identified for enhancements, running from SH 45 North to SH 45 Southeast.

AUSTIN (KXAN) — Two of the Texas Department of Transportation's three Interstate-35 express projects are on track to begin construction this year, officials said Monday.

TxDOT's I-35 Capital Express program is a 28-mile trek identified for enhancements, running from SH 45 North to SH 45 Southeast.

The program is broken down into three components: the Capital Express North, Capital Express Central and Capital Express South projects. Both the northern and southern projects are expected to begin construction this year, said Heather Ashley-Nguyen, TxDOT's transportation planning and development director.

Capital Express North

The Capital Express North project runs from SH 45 North to U.S. Hwy. 290 East, adding one high-occupancy vehicle lane in each direction. A toll fee will not be added to the HOV managed lanes, officials said.

Additional project features includes the reconstruction of six bridges, an added diverging diamond intersection at Wells Branch Parkway, along with 15 miles of pedestrian and bicycle paths, as well as trail connections.

Ashley-Nguyen said construction is expected to begin later this year, with an upcoming construction contract award anticipated in August. The project has an estimated cost of $500 million.

Capital Express Central

The Capital Express Central project is a $4.9 billion, roughly eight-mile-long track extending from U.S. Hwy. 290 East to SH 71 and Ben White Boulevard. The project will construct east-west cross-street bridges and add on pedestrian and bicycle paths.

Key construction highlights include lowered lanes along I-35 at 4th Street, so the frontage road no longer crosses the train tracks, as well as a rebuilding of the Lady Bird Lake bridge and upgrading trail connections.

At the intersection of I-35 and Riverside Drive, a bypass lane is proposed, given future work on Project Connect's Blue Line light rail system. This would allow continuous north-south travel via the bypass lane, even as the light rail system is running.

Currently, TxDOT officials are working toward a draft environmental impact statement, which they expect to complete later this year. The EIS draft will analyze two proposed project configurations, referred to as Alternative 2 and Modified Alternative 3.

TxDOT officials unveiled the Modified Alternative 3 as a a "boulevard-like" concept near the downtown core, said Tucker Ferguson, TxDOT's Austin District engineer. Under the modified third option, both the north and southbound frontage roads would run along the westside of I-35.

An added component of the project being proposed are cap and deck plazas, or public use spaces running on top of decompressed highways. A key example studied by TxDOT engineers is the Klyde Warren Park up in Dallas.

If cap and deck plazas are approved, construction is expected to run alongside the overall Capital Express Central project, but the plazas' costs are not incorporated into the $4.9 billion sticker price. Funding for the multi-billion project comes from TxDOT and the Capital Area Metropolitan Planning Organization.

Those additional funds, considered local enhancements, are being weighed out by the city of Austin, Downtown Austin Alliance, the University of Texas at Austin and the Austin Chamber of Commerce.

KXAN has reached out to TxDOT for preliminary cost estimates for cap and deck plazas.

Preliminary construction estimates anticipate road work will begin in late 2025.

Capital Express South

TxDOT's I-35 Capital Express South project is a $548 million initiative that will add two non-tolled HOV lanes along I-35. The project's boundary extends from SH 71 and Ben White Boulevard to SH 45 Southeast.

The south project will also add two miles of elevated managed lanes from Stassney to Slaughter lanes, which Ashley-Nguyen said "reduces conflict points and enhances safety." Other elements include two miles of intersection bypass lanes, 13 miles of pedestrian and bicycle paths and trail connections.

A construction contract was rewarded in May, with construction set to begin later this year.