Construction is underway on Jefferson County’s first Diverging Diamond Interchange (DDI) in McCalla.
The $22M project will transform Exit 104 on I-59/20 at McAshan Drive.
The exit offers access to the Rock Mountain Lakes community along with the Jefferson Metropolitan Park.
It is home to more than a dozen industrial campuses, including the new $1.1B JM Smucker Uncrustables plant.
The job was awarded to Carcel & G. Construction, with funding coming from three sources:
- $14M: Jefferson County
- $6M: Federal Interstate Maintenance
- $2M: ATRIP-II (Rebuild Alabama Act funds)
Crews are building a new parallel bridge to handle the configuration while the existing overpass across I-59/20 will remain.
As drivers approach one side of the bridge, the DDI design allows traffic to gently transition from the right side to the left and then back again at the other end of the bridge.
Drivers will make all left turns without crossing opposing traffic since it travels on the left side of the bridge.
Federal Highway Administration research shows DDI’s are more cost effective, efficient and safe.
- Up to 75 percent less construction costs
- Up to 50 percent reduction in vehicle conflict points
- Up to 30 percent increase in traffic efficiency
Additional DDI’s are planned for the intersections of I-65 and Lakeshore Drive and the future Exit 9 on I-459.
Motorists should expect temporary lane closures and shifts during the McAshan Drive project, which should last through Fall of 2026.
