TDOT aerial view	Mike Flatt GSP, Alcoa City Manager Mark Johnson, Jason Brady GSP

The City of Alcoa’s newly constructed Diverging Diamond Interchange was recently honored by the American Council of Engineering Companies of Tennessee (ACECTN) at their 22nd Annual Engineering Excellence Awards Reception and Banquet held March 8, 2011 in Nashville. The City of Alcoa along with the project’s design and consulting firm, Gresham, Smith and Partners (GS&P), and the Tennessee Department of Transportation (TDOT) were presented the ACEC’s Grand Award in the transportation category of the organization’s Engineering Excellence Awards program.

The interchange of Middlesettlements Road and Bessemer Street at US 129 Bypass in Alcoa, Tennessee was experiencing increasing traffic volumes and congestion due to additional traffic from the Blount County Industrial Park and new commercial development in this area. In partnership with TDOT, the City of Alcoa and GS&P chose the Diverging Diamond Interchange (DDI) design to alleviate this congestion. The DDI was selected for its operational and safety benefits, significantly lower cost of construction, and its ability to be operational within a year. The $2.9 million interchange optimizes three lanes and saved money that would have been used to build a bridge.

The interchange became the first of its kind in Tennessee and only the fifth to be operational in the United States. The new U.S. 129 Bypass / Bessemer Street / Middlesettlements Road interchange realigns Middlesettlements Road to tie into Bessemer Street. Actually located under U.S. 129, the interchange is the first in the nation in operation that is located beneath a highway.

The ACECTN is a statewide organization of more than 110 engineering companies with chapters in East Tennessee, Chattanooga, Nashville, and Memphis. Through its activities and programs, ACEC of Tennessee works to improve the business practices of engineering firms, enhance public awareness and understanding of the value of engineering services, and influence public policy to promote the safety of Tennesseans. ACEC of Tennessee is a member of the national American Council of Engineering Companies which is headquartered in Washington D.C. The ACEC leads the business interests of over 5,000 engineering firms providing professional consulting services nationwide.

Steve Borden, TDOT Region 1 Director, showed his support of the innovative solution by saying, “As an engineer, any time that we get the opportunity to do something new, something that’s on the cutting edge, it’s very exciting.” Alcoa Mayor Don Mull stated, “The City of Alcoa is proud to be the first in Tennessee to implement this design and want to thank Gresham Smith for proposing this unconventional solution and the Tennessee Department of Transportation for agreeing to let us give it a try. The good news is that it really works as well if not better than envisioned and it saved the taxpayers millions of dollars and months of inconvenience had the traditional solution of replacing the bridge been chosen.”