Diverging diamond intersection now open

City will monitor and adjust signal timing as needed as new traffic patterns materialize

A new type of intersection to help you get on your way faster has opened in Round Rock. The Texas Department of Transportation opened the area’s first-of-its-kind diverging diamond intersection (DDI) at Interstate 35 and RM 1431/University Boulevard at 9 a.m. Friday, Nov. 20.

“Diverging diamond intersections serve as relatively low cost improvements that will bring some much-needed traffic relief to the area,” said John Peters, TxDOT assistant area engineer. “I’m excited for the DDI to open, as this project will greatly enhance safety and help motorists travel along and across the I-35 corridor by improving left-turn movements and allowing more vehicles to travel through the intersection in a single traffic light cycle.”

A diverging diamond intersection temporarily shifts traffic to the left side of the road, allowing through-traffic and left-turning traffic to proceed through the intersection simultaneously. This eliminates the need for left-turn arrows. The new intersection design has proven to decrease the number and severity of crashes by reducing the number of potential conflict points between cross-traffic and left-turn movements.

The project is a joint effort between TxDOT and the City of Round Rock. The City will monitor and adjust signal timing at the DDI throughout the opening weekend as well as during morning and afternoon rush hours in coming days.

The City is also planning changes to traffic signal operations along University Boulevard east of I-35 to maximize traffic flow once the DDI opens.

Drivers who wish to continue north and south on the I-35 frontage roads at RM 1431/University Boulevard will be able to avoid the traffic signal and use the collector-distributor lane, or frontage road bypass lane. The northbound bypass lane has been in operation for years, while the southbound bypass lane opened several months ago. This change means a reduction in delays and travel time at the busy intersection.

“We know that driving through this new type of intersection is different, as it’s the first-of-its-kind in this area, and only the second one to open in Texas,” Peters said. “However, once you get used to it, you’ll find that it is not difficult to understand and navigate. If you follow the traffic signs and road stripes, it will guide you straight through the intersection.”

While the new intersection is scheduled to open this week, final paving for the project won’t occur until the weather warms in the spring.

Capital Excavation has been the contractor on the $6.6 million project, which began in October 2014. You can find more information about the project or to see how to drive through a DDI here.

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