Are Diverging Diamonds The New Roundabouts? City Officials Plan Traffic Solution

2017-04-19 | Columbus Ledger-Enquirer

April 20 --If you've ever had problems navigating the Buena Vista Road / I-185 interchange, there soon may be a solution. But it could require driving on the wrong side of the road, according to city planning officials.

City Planning Director Rick Jones said the city will soon create what's called a Diverging Diamond Interchange at the intersection to lessen conflict points and ease congestion. He said the Buena Vista/ I-185 bridge will have to be reconstructed to accommodate the new DDI design. At a recent city council meeting, he showed a four-minute video from the Washington State Department of Transportation that demonstrated how the interchange would work.

"The best way I know how to describe this without really freaking you out this morning -- because it's going to freak out a lot of folks when we talk about it -- is when this interchange is built you'll actually be driving on the wrong side of the road -- or what you perceive to be the wrong side of the road anyway," he said, " because the traffic goes not from right to right, but it goes left to left."

Jones said the TSPLOST project is already moving forward, but a public information meeting will be held Thursday so residents can look at the maps and see how they will be impacted by the new design. The meeting will be held 5 to 7 p.m. at the Columbus Baptist Association , 3679 Steam Mill Road .

The first DDI intersection was designed in 2009 in Springfield, Mo. , according to the WSDOT video. Since then, more than 60 cities have constructed such intersections throughout the United States , and it's a growing trend.

DDIs provide better mobility for motorists, commercial vehicles and cyclists by decreasing travel time and congestion, the video narrator said. Accidents at high-volume intersections are reduced by about 50 percent.

"In a traditional diamond interchange, traffic signals require three phases to manage the traffic movements, including a separate left-turn phase," according to the video. "By contrast, in the DDI thru-traffic and left turns happen at the same time, eliminating the need for a separate left-turn phase. This creates shorter wait times and allows the interchange to handle higher-traffic volumes more efficiently."

Jones said the DDI would lessen the conflict points and congestion on the Buena Vista/ I-185 bridge when trying to make a left hand turn going south or north in the evenings.

"The whole idea is to lessen, really, the conflict points and the congestion on that bridge," he said. "It does get very hairy at times in dealing with that. We believe this is a solution."

Alva James-Johnson : 706-571-8521, @amjreporter

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