George H. Conner, Deputy Director, Operations | Alabama Department of Transportation
George H. Conner, Deputy Director, Operations | Alabama Department of Transportation
Construction has begun on Jefferson County's first Diverging Diamond Interchange (DDI) at Exit 104 on I-59/20 at McAshan Drive in McCalla. The $22 million project aims to improve access to the Rock Mountain Lakes community and the Jefferson Metropolitan Park, which includes several industrial campuses like the new JM Smucker Uncrustables plant valued at $1.1 billion.
The construction contract was awarded to Carcel & G. Construction, with funding sourced from Jefferson County ($14 million), Federal Interstate Maintenance ($6 million), and ATRIP-II funds from the Rebuild Alabama Act ($2 million). A new parallel bridge is being built for the DDI configuration while maintaining the existing overpass across I-59/20.
The DDI design allows traffic to switch sides of the road as it crosses the bridge, enabling left turns without crossing opposing traffic. According to research by the Federal Highway Administration, DDIs can reduce construction costs by up to 75%, vehicle conflict points by up to 50%, and increase traffic efficiency by up to 30%.
Additional DDIs are planned for other locations, including intersections at I-65 and Lakeshore Drive and a future exit on I-459. Motorists should anticipate temporary lane closures and shifts during this project, expected to be completed by Fall 2026.
Information from this article can be found here.
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