The Loop 1604 North Expansion in San Antonio reached a significant construction milestone on March 23, 2026, as traffic was shifted onto newly built infrastructure at the Blanco Road interchange—marking a visible transition into a new phase of the project.

According to the Texas Department of Transportation and local media reports, a major traffic switch took effect that day, following a weekend of full closures used to complete critical construction work. Crews shut down sections of Loop 1604 and Blanco Road between March 20 and March 23 to carry out bridge and interchange modifications, after which the roadway reopened with a reconfigured layout.

The most notable change is the activation of a diverging diamond interchange (DDI) at Blanco Road—the first of its kind along this corridor. Under the new configuration, traffic briefly crosses to the opposite side of the road to allow for more efficient left turns onto highway ramps. This type of traffic pattern is typically introduced only after substantial structural elements, including bridge decks and ramp systems, are already in place.

The March 23 traffic shift directly reflects ongoing construction and shows that the project has moved beyond early-stage work, including grading and building foundational structures. With crews now operating the interchange in its partially completed final form, they can advance paving, striping, and finishing work across adjacent segments.

Loop 1604 North Expansion

The Loop 1604 North Expansion is a major highway upgrade program valued at approximately $1.4 billion. The project spans roughly 23 miles on the north side of San Antonio. And aims to expand the roadway from four lanes to as many as ten in certain sections. In addition to added capacity, the project includes interchange reconstructions, new bridges, and upgraded frontage roads designed to reduce congestion and improve safety along one of the region’s busiest corridors.

With this latest milestone, the project continues to progress through active construction, with further traffic adjustments and phased openings expected as work advances.

The Loop 1604 North Expansion involves several key partners working under the leadership of the Texas Department of Transportation (TxDOT). STV Inc. serves as the prime construction engineering and inspection consultant, overseeing quality assurance, materials testing, and documentation across multiple segments. LTRA Engineers contributes design, environmental permitting, and traffic analysis, while Parsons Corporation provides engineering and consulting support on select portions of the corridor. Together, these partners coordinate with TxDOT to ensure construction milestones, including the March 23 traffic shift at Blanco Road, are executed safely and efficiently.

Just as the Loop 1604 North Expansion in San Antonio recently reached a major milestone with its diverging diamond interchange opening on March 23, 2026, Kansas is also moving forward with its largest highway project in decades: the $288 million East Kellogg Expansion in Wichita, which will widen the corridor and improve traffic flow for commuters and freight alike.

Factsheet: Loop 1604 North Expansion – San Antonio, Texas

Project: Loop 1604 North Expansion – Blanco Road Interchange Phase

Location: San Antonio, Texas, USA

Owner/Agency: Texas Department of Transportation (TxDOT)

Project Type: Highway widening and interchange reconstruction

Project Cost: Approx. $1.4 billion

Corridor Length: ~23 miles

Scope of Work:

• Expand roadway from 4 lanes to up to 10 lanes in key segments
• Construct new bridges and ramps
• Upgrade frontage roads
• Reconstruct Blanco Road interchange into a Diverging Diamond Interchange (DDI)
• Improve traffic flow, safety, and capacity

Key Milestone (March 23, 2026):

• Major traffic shift implemented at Blanco Road interchange
• Diverging Diamond Interchange activated
• Full weekend closures (March 20–23) used for bridge and ramp work
• Transition into final construction phase, including paving, striping, and finishing

Project Start Date: 2024 (early-stage grading and structural work)

Current Status: Active construction, with portions now open to traffic in final configuration

Significance:

• First DDI along this corridor
• Major capacity and safety improvements for San Antonio’s northern loop
• Key milestone demonstrates visible progress toward project completion

Project Team:

• Texas Department of Transportation (TxDOT) – Owner and project manager
• STV Inc. – Construction Engineering & Inspection consultant, quality assurance, and project documentation
• LTRA Engineers – Design, environmental permitting, traffic analysis, and schematic development
• Parsons Corporation – Engineering and consulting support on select project segment