Could the Diverging Diamond Highway Design Reduce Car Accidents in Nashville?

Photo of Nashville thumbnailNot all innovations involve new technology, but instead just a small but important tweak to an existing design. As local officials continue to look for ways to reduce the number of Nashville car accidents, one method they may find to be effective is the diverging diamond interchange (DDI), which involves making a small but important change to existing intersections.

How Does the Diverging Diamond Highway Design Work?

Diverging diamond interchanges work by crisscrossing the exit and entrance ramps underneath a roadway. The DDI enables drivers to avoid having to make left-hand turns through opposing traffic and makes it very difficult for drivers to mistakenly enter the highway heading in the wrong direction.

A University of Missouri environmental and civil engineer told Wired that left-hand turns through opposing traffic are inefficient and dangerous. This is due to the fact that these types of left-hand turns force opposing traffic to waste green light time to accommodate drivers making left turns, and drivers making left-hand turns to put themselves at risk of suffering 90-degree and head-on collisions.

According to Fortune, five months after a diverging diamond interchange was installed at a highway intersection near Springfield, Missouri, auto accidents fell 60 percent.

Diverging Diamond Interchange Installed on I-40 in Sevierville, Tennessee

A little over a year ago, the Tennessee Department of Transportation (TDOT) announced that a diverging diamond interchange had been completed in East Tennessee on Interstate 40 (I-40) at Exit 407 (State Route 66) near Sevierville. The Sevier County DDI was constructed using stop bars and concrete dividers and involved widening and lengthening the interchange’s exit ramps. It also installed traffic lights and signage that helps guide traffic safely through the intersection.

What resulted was the transformation of the original interchange at Exit 407, which included a concrete cast-in-place bridge, from a more traditional exit into a DDI. Now, vehicles heading in either direction on Interstate 40 at Exit 407 can cross to the opposite side as they exit or enter the freeway. This enables vehicles exiting or entering I-40 to avoid having to make a left-hand turn through opposing traffic and vehicles entering I-40 to avoid entering the interstate headed in the wrong direction.

If the result of the diverging diamond interchange in Springfield, Missouri is any indication, then, hopefully, the DDI in Sevierville will be the first of many that are installed throughout our state. Any innovation that can help make our streets safer here in Davidson County and the greater Nashville metropolitan area is a welcome one.

“Two are better off than one, because together they can work more effectively. If one of them falls down, the other can help him up.”Ecclesiastes 4:9-10

Since 1997, Nashville car accident lawyer Stanley A. Davis has fought tirelessly on behalf of injury victims and their families in the greater Nashville metropolitan area.



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