If you drive through the I-37 and SE Military Drive interchange, a new traffic pattern is coming to this busy stretch of southeast San Antonio. TxDOT plans to build a diverging diamond interchange, or DDI, as part of a nearly two-mile, $40 million project extending along I-37 toward I-410. The project timeline runs from late 2026 through 2029.
So, what is a DDI? It’s an interchange that briefly moves traffic on SE Military Drive to the left side of the road as drivers pass over I-37. Traffic signals guide drivers through a series of crossovers and back to the usual side of the road. That shift lets drivers turn left onto or off I-37 without crossing opposing traffic. TxDOT says the design removes those left-turn conflicts, reduces places where vehicles’ paths cross, and makes it easier to enter and exit the highway.
Why build it near Brooks? The I-37 and SE Military Drive interchange is already heavily traveled. It sits within the Brooks Area Regional Center, where TxDOT expects traffic to increase as the area continues to develop. The new interchange is intended to address congestion and safety challenges while improving access through this growing part of San Antonio.
Plans also include a bypass ramp above the interchange, a new southbound I-37 frontage road that transitions into an additional lane toward the I-410 exit, and 10-foot-wide shared-use paths in both directions for people walking and biking. TxDOT says no additional right-of-way is needed and no displacements are anticipated.
Drivers should expect temporary lane closures during construction. TxDOT says most closures will happen on weekdays between 9 p.m. and 5 a.m., although work may also take place during the day and on weekends. The agency plans to announce closures and access changes in advance.
See the project map, preview video, and updates on TxDOT’s I-37 project page.
Source & Images: txdot.gov
