Officials Celebrate Round Rock Divergent Diamond Intersection Success [UPDATE]

ROUND ROCK, TX -- State and local officials gathered Monday to celebrate the full project completion of the diverging diamond intersection, a traffic-calming device that is the first of its kind in Central Texas.

State transportation officials said the diverging diamond was working "extremely well." Located at the intersection of Interstate 35 and RM 1431/University Boulevard, he divergent diamond device was installed November 2015.

Since is installation, Texas Department of Transportation officials said they have run some metrics to determine its effectiveness. The upshot: Despite a 45 percent increase in traffic volume at this intersection over the last four years, the road feature has already yielded a 13 percent reduction in morning and a 44-58 percent decrease in afternoon travel times, transportation officials said.

In plain English, this means that even though a lot more cars are traveling through this area, they're getting through one of Round Rock’s most congested intersections much quicker than before, officials said.

“While this innovative intersection design was initially confusing to some motorists, the improvement to traffic flow here has been straightforward: It works,” Mayor Alan McGraw said. “It’s rare indeed when you can say that traffic volume has increased but travel times have actually decreased, and by a significant amount. But that’s the case with the diverging diamond intersection, the latest successful partnership between the city and TxDOT.”

The effectiveness of the diverging diamond intersection yields a measure of vindication for transportation officials. By and large, motorists had been skeptical drivers would adapt to this never-before-seen feature and some even predicted more accidents would be caused as a result.

(The device is unlike anything found in Central Texas before, allowing drivers entering into the left side of the roadway in deciding to turn north or south, thereby allowing through- and left-turning traffic to proceed. A DDI increases traffic flow through this shifting of traffic to the left._

“People thought we were crazy when we first proposed this idea, but now that the project is complete, the proof is in the pudding,” Terry McCoy, Austin District engineer, said. “The Austin District will continue to pull out all the stops to find cost effective and innovative ways to deal with the region’s growing congestion. Recognizing that innovative intersections may require a period of adjustment for drivers, they are proving their worth.”

Work on the $6.6 million project included the construction of a diverging diamond intersection, as well as a number of other improvements, transportation officials noted. Among those enhancements are an intersection bypass road, ramp improvements and additional sidewalks for pedestrians and cyclists.

*************************************************************************************************

From May 15:

ROUND ROCK, TX -- It's not every day that city and state officials gather to celebrate the installation of a traffic-calming device installed six months earlier.

But this is no ordinary traffic-calming device. It's the diverging diamond intersection project at Interstate 35 and RM 1431/University Boulevard.

At the time of its installation, the divergent diamond was the first in Central Texas and only the second in Texas after El Paso itself its version, the Round Rock Leader newspaper reported at the time.

On Monday, Texas Department of Transportation officials plan a celebration of sorts for the success of the $6.6 million project installed last November.

The Texas Department of Transportation, in cooperation with officials from Williamson County and the city of Round Rock, will celebrate the full project completion of the project. Officials will share results on the operation of the innovative intersection.

The diamond allows drivers entering into the left side of the roadway in deciding to turn north or south, thereby allowing through- and left-turning traffic to proceed. A DDI increases traffic flow through this shifting of traffic to the left.

Through-traffic and vehicles turning left can continue on the roadway at the same time. With a DDI, the need for left-turning green arrows is eliminated, allowing enhanced flow of traffic volume.

Officials will gather May 16 at 2 p.m. for their diamond celebration. The gathering will occur at the northeast corner of Interstate 35 and RM 1431 intersection in the University Commons shopping center parking lot.

>>> Illustration and video courtesy of the Texas Department of Transportation