Texas Department of Transportation – Diverging Diamond Interchange (March 5, 2026)
SAN ANTONIO (KTSA News) — The Texas Department of Transportation (TxDOT) is entering the final phase of construction on a new diverging diamond interchange (DDI) at Blanco Road and Loop 1604.
It is part of the ongoing Loop 1604 North Expansion.
TxDOT says it is the first of its kind in San Antonio and the eighth DDI constructed in Texas.
“Our team is excited to bring San Antonio its first diverging diamond interchange,” said San Antonio District Engineer Charles Benavidez, P.E. “DDIs have been shown nationwide to reduce crash rates by up to 60 percent, and we are optimistic this design will deliver similar safety and mobility benefits for drivers along Blanco Road once it is complete later this year.”
How a DDI works
A DDI is an innovative intersection design that temporarily shifts traffic to the left side of the road, allowing easier and faster turns without a dedicated signal. By reducing conflict points and simplifying turning movements, DDIs help traffic flow more smoothly and reduce congestion at busy intersections.
Why the DDI benefits drivers
The DDI at Blanco Road and Loop 1604 is designed to make travel easier, faster, and safer by:
Allowing continuous left-turn movements without a separate signal phase
Reducing the number of conflict points where crashes can occur
Improving traffic flow during peak travel times
Enhancing mobility along one of the region’s most heavily traveled corridors
What to expect during the final phase of construction
Beginning in March 2026, drivers will see a new traffic pattern as the intersection transitions into a DDI configuration. This will allow crews to begin the final phase of construction for the DDI, which is expected to be complete in late summer 2026.
During this phase, drivers should expect the following:
Traffic on Blanco Road will shift to the left when crossing Loop 1604
Through traffic on Loop 1604 frontage roads must use the bypass lanes
Temporary traffic signals will be in operation
Barriers will be installed to allow for construction of concrete islands
Pedestrian access may be limited
Weeknight closures will continue as needed
The traffic switch date and time will be announced once confirmed. Drivers are encouraged to slow down, follow posted signs, and remain alert while traveling through the work zone.
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