TxDOT Closes San Antonio I-35; Expect Frontage Road Delays

San Antonio drivers who need Interstate 35 tonight face a full mainlane shutdown, not a single-lane squeeze. The Texas Department of Transportation is closing northbound and southbound I-35 between Rittiman Road and George Beach Avenue from 6 p.m. Sunday, August 23, until 5 a.m. Monday, August 24, so crews can set beams.

Traffic will move onto the frontage roads for that stretch. Expect delays if you are headed to or from San Antonio International Airport, downtown hotels, or the Austin corridor during the overnight window.

What TxDOT closed and why it matters tonight

According to the TxDOT San Antonio traffic alert posted Sunday, both directions of the I-35 mainlanes close from Rittiman Road to George Beach Avenue. The work is beam setting, which needs a clear roadway for crane and placement crews.

MySA reported the same Sunday window and said drivers will be forced onto the frontage roads. That independent local account matches the official limits and times, which is the traveler decision for tonight.

A full overnight closure is different from the staggered nightly lane cuts many drivers already know from the I-35 Northeast Expansion work. When both directions lose their mainlanes at once, through traffic has nowhere left but the frontage system.

That matters for anyone timing a late arrival into San Antonio, an early Monday departure toward Austin, or a rideshare or rental-car transfer that assumes freeway speeds after dark.

How the frontage-road detour will feel

TxDOT says traffic will be detoured to the frontage roads for the closed segment. Frontage roads keep you moving, but they add signals, driveways, and local traffic that freeways normally bypass.

Plan for stop-and-go pockets near ramps and intersections even if the map still looks short. A drive that usually takes a few minutes on the mainlanes can stretch when every vehicle from both directions shares the same surface streets.

If you are unfamiliar with the Northeast Side, stay in the signed detour rather than inventing a cut-through. Improvised side streets can dump you into neighborhoods or dead ends that cost more time than the official route.

Overnight truck traffic and late airport runs often share these same frontage roads. Leave a buffer if you have a fixed hotel check-in, a flight, or an early work start on Monday.

Who should change plans before 6 p.m.

Travelers using San Antonio as a Sunday night waypoint on the Austin to South Texas corridor should treat 6 p.m. as a hard decision point. Crossing the Rittiman to George Beach segment after that hour means accepting frontage-road speeds.

Airport-bound drivers are in the same boat. San Antonio International Airport sits on the north side of the city, and many downtown, River Walk, and hotel shuttles rely on I-35 for the final approach.

If your itinerary can flex, leave before the closure or wait until after 5 a.m. Monday. If it cannot flex, rebuild the route now and tell companions the freeway will not be available.

Rideshare and rental customers should also reset pickup timing. Drivers stuck on frontage roads will run later than Sunday night map estimates that still assume open mainlanes.

For a destination-level plan once you clear the construction zone, Deep Arrival’s things to do in San Antonio guide covers the core visitor circuit without assuming a specific freeway approach.

Other weekend restrictions tied to the same corridor

MySA also listed concurrent local restrictions at Loop 1604 and Blanco Road. Eastbound and westbound Loop 1604 frontage traffic at Blanco Road is limited to local destination trips, with no through traffic approaching Blanco Road.

Blanco Road at Loop 1604 carries the same local-only rule. Those limits also run through 5 a.m. Monday, weather permitting, according to the local report summarizing TxDOT guidance.

Drivers who hoped to dodge the I-35 beam work by swinging west toward Loop 1604 still need to check that interchange. A local-only restriction can strand through traffic that assumed the outer loop would stay fully open.

Treat the I-35 mainlane closure as the primary traveler decision, then verify Loop 1604 and Blanco as a secondary check if your alternate path touches that interchange.

How this fits the larger I-35 construction pattern

San Antonio’s I-35 corridor has been under phased expansion for months, with repeated overnight lane and ramp work on the Northeast Side. Sunday’s alert is another timed window inside that program, not a random one-night accident shutdown.

Drivers who follow TxDOT San Antonio alerts through the week already know the pattern: short overnight windows, signed detours, and a Monday morning reopen target. The difference tonight is the full mainlane takeover on a named segment instead of a single-lane reduction.

Beam setting is structural work. Crews need both directions clear so they can place beams safely and reopen the mainlanes for Monday morning demand.

That is why the alert quotes a firm overnight envelope instead of an open-ended “until further notice” ground stop. The traveler action is date-specific: get through before 6 p.m., or accept the detour until 5 a.m.

Weather can still stretch the calendar. TxDOT and local reporting both flag the usual weather-permitting caveat, which is why a final DriveTexas check remains part of the plan even after you memorize the posted hours.

Practical timing for airport, hotel, and through trips

Sunday evening is a common arrival window for leisure travelers landing at San Antonio International Airport and continuing downtown. If your flight lands after about 5 p.m., assume the ground leg may hit the closure and leave more time for the frontage-road hop.

Hotel shuttles and rental-car returns that normally use I-35 should get the same warning. Tell the desk or the app that the mainlanes are closed between Rittiman Road and George Beach Avenue so the driver does not chase a dead freeway ETA.

Through travelers between Austin and South Texas face a different choice. Clearing the segment before 6 p.m. keeps freeway speed. Waiting until after the evening rush only to hit the beam-setting window can cost more time than leaving earlier or stopping for dinner north or south of the work zone.

Monday morning reverse traffic matters too. The posted reopen time is 5 a.m., but the first wave of trucks and airport runs can still meet residual congestion while crews clear equipment. Build a cushion for early flights even after the official end time.

If your route includes that San Antonio I-35 segment tonight, clear it before 6 p.m. or budget frontage-road time through 5 a.m. Monday.