Tennessee's First Diverging Diamond Interchange to Open

KNOXVILLE, Tenn. – In an effort to conserve land, capitalize on three travel lanes, and save time and money, the Tennessee Department of Transportation and the city of Alcoa teamed up to build the state’s first diverging diamond interchange. On Tuesday, December 14 the new interchange will be fully opened to traffic. 

 

Increased industrial and commercial growth led city of Alcoa community leaders to search for an innovative way to improve traffic congestion under the U.S. 129/State Route 115 bypass bridge between Middlesettlements Road and Bessemer Street. After collecting public input, Alcoa officials decided to utilize the new Diverging Diamond Interchange design and the city will now be the site of the fifth diverging diamond interchange in the country. 

 

“The option to build a $2.9 million dollar interchange that uses an innovative geometric design made sense when it was compared to spending more to build another bridge and construct additional lanes,” Alcoa Mayor Don Mull said. “We believe this option will improve traffic flow and will become a model for other communities facing the same situation.” 

 

Gresham Smith and Partners designed the unique crisscross interchange and construction started in February 2010. The diverging diamond design uses concrete dividers, stop bars, traffic signals and extensive signage to guide traffic through the unique interchange.

 

“We know it will take time and patience for people to become familiar with the new design, but we believe motorists will come to appreciate some of the free flowing features,” TDOT Commissioner Gerald Nicely said. “This interchange will improve safety by reducing speeds while eliminating the previous left turns that put motorists in the path of oncoming traffic.”

 

Crews opened the eastbound lanes to traffic on Saturday, December 11, 2010 and will open the westbound lanes on Tuesday, December 14.  

 

Diverging Diamond Interchanges are currently in use in Missouri and Utah. At least nine other states are constructing or considering Diverging Diamond Interchanges. As a result, the Federal Highway Administration will study the functionality of the Alcoa interchange to determine the future use of diverging diamond designed interchanges in other parts of the country.  

 

 

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