I-37 Operational Improvements in San Antonio: $32.8M TxDOT Project to Transform I-37 & SE Military Drive Interchange
For the thousands of drivers who travel between I-37 and SE Military Drive (State Loop 13) each day, congestion and safety concerns have become part of the routine. A new Texas Department of Transportation (TxDOT) project aims to change that — reshaping one of South San Antonio’s busiest corridors to improve mobility, reduce crashes, and prepare for continued growth in the Brooks Area and surrounding Bexar County communities.
The IH 37 (CSJ: 0073-08-183) Operational Improvements Project, stretching from IH 410 to SL 13 (SE Military Drive), represents a $32,801,454 public infrastructure investment funded through public and federally supported roadway dollars. Construction is scheduled to begin June 1, 2026, with completion anticipated by September 1, 2028, according to official permit filings.
For residents, commuters, and businesses near City Base, Brooks, and Southeast San Antonio, the improvements are designed to ease daily travel and improve long-term traffic flow in a rapidly developing corridor.
Why This I-37 Project Matters to San Antonio Drivers
The 1.95-mile project corridor has experienced steady traffic growth. According to TxDOT’s materials, annual average daily traffic is projected to increase significantly in coming years as redevelopment continues in the Brooks Area Regional Center.
Without improvements, drivers could experience substantial delays — especially during peak hours. A traffic analysis presented during the August 28, 2025 open house found:
- Travel time reductions of approximately 46% southbound
- Travel time reductions of approximately 81% northbound
- Up to 90% reduction along key interchange routes during 2028 peak hour conditions
For commuters heading to downtown San Antonio, Joint Base San Antonio, or employment centers in the Brooks corridor, these changes could mean a noticeably shorter and more predictable drive.
(Source: TxDOT)What’s Being Built: Diverging Diamond Interchange (DDI) and Ramp Improvements
At the heart of the project is a conversion of the existing I-37 and SL 13 interchange into a Diverging Diamond Interchange (DDI) — an innovative intersection design that temporarily shifts traffic to the opposite side of the roadway within the interchange to improve efficiency and reduce conflict points.
- Key Components of the I-37 Construction Project
- Conversion to a Diverging Diamond Interchange (DDI)
- Construction of a southbound overpass
- Extension of the southbound frontage road
- Addition of an auxiliary lane toward IH 410
- Addition of a shared use path (SUP) for bicyclists and pedestrians
- Drainage improvements including culvert extensions and storm drain upgrades
- No additional right-of-way acquisition required
- No anticipated residential or business displacements
The shared use path is particularly notable for families and cyclists in the Brooks and Southeast Military Drive area, offering safer multimodal connectivity.
Safety Improvements Along I-37 in Bexar County
Safety has been a central driver of the redesign. A crash analysis between 2019 and 2024 identified:
- Three reported fatalities
- Eleven serious injury crashes
- The highest crash frequency concentrated at the I-37 and SL 13 interchange
By reducing traffic conflict points and improving interchange flow, the DDI is expected to enhance overall roadway safety.
Environmental Review and Floodplain Considerations
TxDOT is conducting environmental review under the National Environmental Policy Act (NEPA). According to the open house materials, the project:
- Is a re-evaluation of a previously cleared 2016 frontage road project
- Requires no additional right of way
- Anticipates no displacements
- Is not expected to impact the 100-year floodplain
Drainage upgrades will include culvert extensions, a concrete-lined ditch, storm drain replacement at the SL 13 interchange, and upsized culverts near the southern project limits.
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Project Timeline: What Happens Next
The project schedule outlined during the August 2025 open house indicates:
- Late 2025: Completion of schematic design and environmental technical reports
- Early 2026: Environmental clearance
- May 2026: Project letting (construction bidding)
- June 1, 2026: Anticipated construction start
- September 1, 2028: Estimated completion
All dates remain preliminary and subject to change.
Who Is Leading the Project?
Owner: TxDOT San Antonio District
Design Firm: Kimley-Horn & Associates, Inc.
Facility Name: CSJ: 0073-08-183
Location: From IH 410 to SL 13 (SE Military Drive), San Antonio, Bexar County
The estimated construction cost for the current phase is $32.8 million, reflecting public investment in long-term transportation infrastructure for the region.
What San Antonio Residents Should Expect
Construction along major corridors can temporarily disrupt routines. However, for families commuting to schools, workers traveling to downtown or Brooks, and businesses depending on reliable access, the long-term goal is a corridor that moves more efficiently and safely.
As Southeast San Antonio continues to grow, projects like the I-37 Operational Improvements Project aim to balance mobility, safety, and economic development.
For continued coverage on infrastructure improvements, transportation updates, and community development in Bexar County, stay tuned to My Neighborhood News.
Tiffany Krenek has been on the My Neighborhood News team since August 2021. She is passionate about curating and sharing content that enriches the lives of our readers in a personal, meaningful way. A loving mother and wife, Tiffany and her family live in the West Houston/Cypress region.