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April 2025: Issue 28
In this issue
- I-35 NEX South Phase 3
- Going to Great Lengths for Safety
- 35 Second Behind I-35 NEX
- Weidner Road Exit on Southbound I-35 Reopens
- Concrete Strength Testing
- Helping Out the Community
- Active Construction Sites
- Contact Us
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The I-35 Northeast Expansion (NEX) Program covers approximately 20 miles of I-35 from N. Walters Street to FM 1103 in Bexar, Comal, and Guadalupe Counties. The I-35 NEX Program–including Central, South, and North projects – involves the construction of two elevated structures that will carry two general purpose lanes and one HOV lane in each direction. The elevated structures will be constructed between the existing I-35 mainlanes and frontage roads. The program also includes incidental construction necessary to transition the elevated lanes and connectors with the existing highways including revisions to ramps and frontage roads and accommodations for drainage, utilities, signs, and other highway improvements.
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What is happening just a little south of the I-35 NEX South Phase 1 project? Phase 3 of the I-35 NEX South project - I-35/I-410 South Interchange to FM 78 (1.14 miles) began construction in late March and consists of a full reconstruction of I-410 at FM 78 and expansion of I-410 from 4 lane to 6 lane expressway with intersection operational improvements of frontage roads and cross streets. The $84.5M project also includes upgrading drainage, utilities and signage. The expected completion date of the South Phase 3 project is late 2028.
When driving through construction zones, it's easy to feel frustrated by the length of the lane closure. However, it's important to remember that these distances are not arbitrary. They are regulated and designed by experts in the field, with safety as the primary concern for both the traveling public and the construction crews.
Here is an example of the distance of a single-lane closure on a highway with a 65-mph speed limit. The taper length, the distance in which barrels begin blocking the lane is around 750 feet. The buffer space, the distance from the end of the taper to the start of the work area is around 400 feet or longer if the road curves. That is roughly 1,150 feet, nearly four football fields, of safety space before the work zone. These distances double per every lane closed. Additional space is also needed for construction vehicles, equipment, and materials.
This design aims to provide protection for workers and give drivers sufficient time to navigate clear of the work zone. If the lanes are reduced immediately around the construction zone, there is no safety buffer if a driver fails to slow down. The consequences of not adhering to these safety regulations can be severe, including collisions, injuries, and even fatalities.
 Illustration of the distances of a single-lane closure on a highway.
 Newly completed bridge deck at southbound I-35 and Toepperwein Road
35 seconds behind I-35 NEX is a snapshot of the project's progress on I-35 NEX. The bridge deck of the elevated lanes on southbound I-35, south of Toepperwein Road, is complete, and the northbound I-35 elevated lanes are in the process of being poured. The column caps at the I-35 and the I-410 interchange are complete and awaiting the installation of bridge beams, which are scheduled for later this year. Bridge deck work on the bypass lanes of Loop 1604, spanning the Union Pacific Railroad, is in progress. See the progress we've made in those areas and others.
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 Southbound I-35 Weidner Road Exit
Check out the progress on the I-35 NEX project. The southbound I-35 exit to Weidner Road, which has been closed since November 2024 for drainage, column, and straddle bent work, is now open! But wait...the good news doesn't stop there. There are additional I-35 exit and entrance ramps that are expected to open in the coming months.
 Concrete reaches about 90% of its final strength after about four weeks, but it continues to strengthen for decades.
Concrete has excellent compressive strength, and it is the ideal material for constructing our strong and dependable I-35 NEX elevated lanes. “Compressive strength” refers to the amount of pressure that the material is able to withstand.
But just how strong a batch of concrete is matters, and it varies depending on the use. A concrete mix designed for sidewalks has a compressive strength of about 3,000 psi. The concrete in a column can need a compressive strength of up to 8,000 psi. PSI = pounds per square inch, the pounds of pressure applied to a one-square-inch area. It’s the measure used to determine concrete’s compressive strength.
On TxDOT projects, concrete is tested by the quality teams. A cylinder of the concrete poured for the elements of the road structure, for instance a column that will support the elevated lanes, is put under increasing pressure using special lab equipment until it breaks, to assure that its compressive strength is up to our specifications. Click on the image below to see a short video of an actual concrete test.
 The I-35 NEX Central and South Phase 1 project teams grabbed trash bags and participated in the annual citywide Basura Bash. The event allowed both project teams, joined by friends and family to spend the morning picking up trash to show their support of the community they serve.
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Below is a list of notable active and upcoming construction work. Click on maps for more information. Please note that closures are subject to change.
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One or two mainlanes of I-35 in either direction from north of Walzem Road to Petroleum Drive will be closed for median reconstruction. At least one mainlane will remain open in both directions at all times.
The lane closures will occur on weekends (Friday through Monday) 9 p.m. until 5 a.m. through spring 2025.
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Nightly closures of westbound mainlanes of Loop 1604 from Pat Booker Road to Lookout Road and the Lookout Road intersection at Loop 1604 for bridge deck work. Traffic should follow detour signs.
The closure will occur periodically through March 2026.
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Nightly closures the eastbound mainlanes of Loop 1604 from Lookout Road to IKEA-RBFCU Parkway and the Lookout Road intersection at Loop 1604 for bridge deck work. Traffic should follow detour signs.
This closure will occur periodically through March 2026.
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The southbound entrance ramp to I-35 south of O’Connor Road is closed for bridge structure work.
The closure is in progress through May 2025.
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Exit 174A, the FM 1518/Evans Road exit on northbound I-35 will be closed for approximately eight months or until the new exit ramp is constructed. This closure is necessary for drilled shaft work.
This closure is in progress and is scheduled to end early May 2025.
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The southbound I-35 exit ramp to Thousand Oaks Drive/Starlight Terrace is closed for drilled shaft and column work from 9:00 p.m. to 5:00 a.m. until early May 2025. |
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The northbound I-410 entrance ramp south of Greatfare will be closed until early summer 2025 for bridge work. |
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TxDOT San Antonio District
Public Information Office
4615 NW Loop 410
San Antonio, TX 78229
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E-alert
Sign up for weekly lane closure notices and newsletters by emailing us at i35NEX@txdot.gov
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