The Texas Department of Transportation is set to begin construction this year in Round Rock on an innovative traffic management system that will divert drivers to the left side of the road.

Known as a Diverging Diamond Intersection, or DDI, the design is being planned for the University Boulevard bridge that passes over I-35. The bridge has been targeted for improvements by TxDOT—which manages the roadway—because of the high volume of existing traffic and the expected increase of drivers resulting from multiple new business and housing developments along University Boulevard.

Although the design has been used elsewhere in the U.S. for a number of years, Round Rock’s DDI will be the first of its kind in Texas.

“This [specific] design is particularly effective where you have high volumes of left-turn traffic—that is why this was chosen here,” TxDOT spokeswoman Kelli Reyna said. “This doesn’t work everywhere. You have to pick the innovative intersection that fits the needs of the area you are trying to fix.”

The intersection will work by diverting University Boulevard through-traffic to the left side of the road as it crosses over I-35. By diverting vehicles onto the left side of the road, the design allows drivers to turn left onto the I-35 entrance ramps without crossing in front of traffic. Motorists exiting I-35 onto University Boulevard will be able to turn left or right but will not be able to proceed straight across the intersection. Instead, a collector/distributor lane running underneath the bridge will allow motorists to cross the intersection without interfering with University Boulevard traffic.

Round Rock City Manager Steve Norwood said relieving congestion at the intersection is imperative with the ongoing developments along University Boulevard, including the recently opened H-E-B grocery store and In-N-Out Burger restaurant.

“This is going to be a learning curve for all of us, but anything we can do to improve traffic and congestion in that area is a plus,” Norwood said. “I don’t think we can be close-minded on any sort of change regardless if it is not the norm.”

Reyna said TxDOT expects to select a contractor for the $4 million project by June and intends for construction to begin by late summer or early fall. Construction is expected to take approximately one year to complete, she said.


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