Major Downtown I-35 Closure and Loop 1604 Traffic Shifts Highlight Thursday Commute

Morning Commute Overview

Commuters in San Antonio should prepare for significant travel adjustments this Thursday, March 5, 2026. While the morning rush is beginning with standard congestion, two major long-term infrastructure projects are currently dictating traffic flow across the city. The Texas Department of Transportation (TxDOT) continues its intensive work on the downtown I-35 corridor and the Loop 1604 North Expansion, both of which are causing localized delays and requiring new driving habits from local motorists.

Major Arteries and Lane Closures

The most critical disruption remains the total closure of the southbound lower level of I-35 through the downtown San Antonio area. This closure, which spans from the I-37 interchange to I-10, is part of a $25.9 million project to repair bridge joints. Drivers are advised of the following:

• I-35 Southbound: The lower level is completely closed until mid-March. All southbound traffic must utilize the upper level lanes. Expect heavy bottling at the merge points near the I-37 split.
• Loop 1604 at Blanco Road: Traffic patterns have shifted as TxDOT implements San Antonio’s first diverging diamond interchange (DDI). Drivers on Blanco Road are now crossing to the left side of the roadway over the highway. Frontage road bypass ramps are in effect, and motorists should watch for new temporary signals in the Stone Oak area.
• I-10 and US-90: While several overnight maintenance projects on westbound US-90 near Pine Street and I-10 near Steves Avenue were scheduled to conclude at 5:00 a.m. this morning, early commuters may still encounter residual slow-downs as crews remove barriers and signage.
• FM 3351: Be aware of ongoing rail painting work between Fair Oaks Parkway and Keenelan Drive, which may result in intermittent lane narrowings until 5:00 p.m. today.

VIA Metropolitan Transit Alerts

VIA riders should anticipate detours on several key routes today. Extensive construction across the metro area has forced route modifications for the following services:

• Route 7 (US 281 Express): Multiple detours are in place near the Brooks Transit Center and the San Antonio International Airport due to ongoing corridor improvements.
• Route 34 & 36: Service disruptions continue along South St. Mary’s and South Presa as part of local utility and streetscape projects.
• Route 93 (Roadrunner Express): Detours remain active near the Crossroads Park & Ride and the Loop 1604 access points.

Additionally, transit users on the city's West Side should be aware of a continued police presence near the transit center in the 3200 block of Northwestern Drive following a serious security incident late Wednesday night. While service is running, commuters are encouraged to remain vigilant.

Commuter Recommendations

For those traveling southbound through the city center, consider using I-10 or the I-410 loop as an alternative to avoid the upper-level congestion on I-35. In North San Antonio, give yourself an extra 10 to 15 minutes to navigate the new traffic configuration at Blanco Road and Loop 1604, as many drivers are still adjusting to the "braided" lane design.