A major transportation project is underway just south of Birmingham, in McCalla, aiming to improve traffic flow and safety along a key corridor.
New Interchange in McCalla
The Alabama Department of Transportation announced a $22 million Diverging Diamond Interchange (DDI) at Exit 104 on Interstate 59/20 at McAshan Drive. This modern design, first installed in Springfield, Missouri, in 2009, allows drivers to make all left turns without crossing oncoming traffic. ALDOT says the DDI is both cost-effective and safer than conventional intersections.
The new interchange will provide better access to the Rock Mountain Lakes community and Jefferson Metropolitan Park, while serving a corridor that includes industrial hubs such as the $1.1 billion JM Smucker Uncrustables plant.
Funding and Construction Timeline
Jefferson County is covering $14 million of the project, with the remaining $8 million coming from federal and state sources. The Rebuild Alabama Act contributes $2 million, and $6 million comes from the Federal Interstate Maintenance Fund. Construction will continue through fall 2026, and drivers should expect temporary lane closures and traffic shifts as work progresses.
Traffic and Safety Benefits
DDIs are known to reduce construction costs by 75%, lower vehicle conflict points by 50%, and increase traffic efficiency by 30% compared to standard intersections, according to the Federal Highway Administration. Alabama opened its first DDI in Baldwin County in 2020, and there were 150 such interchanges nationwide as of June 2024.
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