Diverging Diamond Interchange
Diverging Diamond Interchange (DDI)
In early 2015, the North Carolina Department of Transportation converted Exit 28 from a traditional diamond interchange to a Diverging Diamond Interchange (DDI). The DDI allows two directions of traffic to temporarily cross to the left side of the road while on the bridge over I-77. Once on the left side of the road, vehicles can turn left onto the I-77 ramps without stopping and without conflicting with through traffic, providing easier access to the highway. View this aerial rendering which illustrates traffic patterns.
The Town worked with NCDOT to improve upon the standard NCDOT DDI design, by aesthetically modifying the design features and eliminating some unattractive features. For example, constructing brick sidewalks and decorative walls instead of using standard concrete; planting bushes and trees in suitable areas instead of using concrete; and adding lighting in the center median for pedestrians. Additionally, large overhead directional signage was removed from the plans, high mast lights were relocated, and the number of signs was minimized. The first phase of the aesthetic improvements is complete.
The second and final phase of the aesthetic improvements will include installation of landscaping in the areas adjacent to the interstate and ramps. The Town has engaged a landscape architect to develop the design.
The Town is also working with NCDOT and I-77 Mobility Partners to locate the second phase aesthetic improvements relative to the I-77 Managed Lanes project. The construction and completion of the DDI aesthetic improvements is pending this cooperative effort.
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