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 the DDI aesthetic design and this aerial rendering which illustrates traffic patterns.  

Current Conditions
ALL lanes on the Exit 28 bridge over I-77 are open to through traffic. Please continue to be patient with fellow drivers, especially our out-of-town guests.

Aesthetic Improvements
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 with the following elements constructed and completed:

  • All overhead utilities have been buried
  • Brick pavers and granite lined sidewalks in the pedestrian islands
  • Colored concrete borders in the pedestrian islands
  • Decorative traffic signal mast arms and monopoles
  • Decorative concrete walls in the center median
  • Colored concrete sidewalk in the center median
  • Masts & cables
  • Lighting along the center median and on the masts & cables
  • Weathered guardrail
  • Landscaping in the pedestrian islands
  • Decorative sign posts
  • Selective landscape removal at the interstate level
The second and final phase of the aesthetic improvements will include construction of the following:

  1. Four masonry abutments at the interstate level
  2. Landscaping adjacent to the abutments and ramp areas
The Town is working with NCDOT and Cintra to locate these 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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