I-35 NEX South Project – San Antonio, Texas

Best Bridge - Structural

The Texas Department of Transportation (TxDOT) is continuing the expansion of I-35 through Bexar County, and the I-35 NEX South Project is the second of five NEX projects improving the corridor. Under construction since June 2024with an anticipated completion in late 2028, this design-bid-build effort delivers 6.4 miles of non-tolled improvementsat an estimated cost of $1 billion.

The project includes the construction of two elevated structures in each direction, built between existing main lanes and frontage roads, in some of the most constrained right-of-way conditions along a heavily trafficked interstate.

Fast Facts

• Award: Best Bridge – Structural

• Project: I-35 NEX South Project

• Location: San Antonio, Texas

• Owner: Texas Department of Transportation (TxDOT)

• Delivery: Design-Bid-Build

• Scope: 6.4 miles of non-tolled improvements

• Construction: June 2024 → late 2028 (anticipated)

• Estimated Cost: ~$1 billion

Why precast mattered here

This work is happening in constricted areas along a live interstate, so time and space are the real “materials” being managed.

To reduce public impact, installation of precast members is performed primarily at night. Using precast/prestressed components allows the contractor to close one or two lanes for a few hours, instead of permanently closing multiple lanes for extended durations.

I35

Precast scope (supplied by Bexar Concrete Works)

Bexar Concrete Works is supplying major bridge substructure elements, including:

• 49 straddle bents

• 75 hammerhead caps

• 78 columns, including column shell pieces

Column fabrication and installation can be adapted for differing height requirements, providing flexibility in design and field conditions.

Project Team:

• Precast Concrete Manufacturer: Bexar Concrete Works (San Antonio, TX)

• Precast Concrete Engineer: AECOM (Dallas, TX); Unintech Engineers (San Antonio, TX); Decon Engineers (San Antonio, TX)

• Engineer of Record: AECOM (Dallas, TX)

• General Contractor: Lonestar Constructors (San Antonio, TX)

• Owner: Texas Department of Transportation (Austin, TX)