Map of the proposed project area on I-59/20 at exit 104 in McCalla.
Special to the News
Construction is underway on Jefferson County’s first Diverging Diamond Interchange (DDI) in McCalla.
The $22 million project will transform Exit 14 on I-59/20 at McAshan Drive.
The job was awarded to Carcel & G. Construction, with funding coming from three sources.
Jefferson County pitched in $14 million, adding to $6 million in Federal Interstate Maintenance funds and another $2 million in Rebuild Alabama Act (ATRIP-II) money.
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 will allow traffic to gently transition from the right side to the left and then back again at the other end of the bridge.
Since traffic travels on the left side of the bridge, all left turns are made without having to cross opposing traffic.
Federal Highway Administration research shows DDI’s are more cost effective, efficient and safe.
Statistics suggest DDI’s lower construction costs by up to 75 percent, vehicle conflict points by up to 50 percent and bump traffic flow efficiency by as much as 30 percent.
Additional DDI’s are planned for the intersections of I-65 at Lakeshore Drive and the future Exit 9 on I-459.
Motorists should expect temporary lane closures and shifts during the project, which should last through fall of 2026.
ALDOT’s mission is to provide a safe, efficient, environmentally sound transportation network across Alabama. For further information, visit aldotnews.com.
