Click on the picture to watch a video of the Springfield DDI in in action.
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What is a Diverging Diamond Interchange?
A diverging diamond interchange is type of interchange in which the two directions of traffic actually cross to the opposite side.
While that sounds confusing or at the least, unusual, there is actually a significant improvement in safety since there are no left turns against opposing traffic. In fact, the Federal Highway Administration thoroughly researched the concept and also found a number of benefits including:
- Fewer conflict points
- Better sight distance
- Reduced speeds
- Simpler signal timing and geometry
- More difficult wrong way entry onto ramps
- Less infrastructure to construct, maintain, and replace
- 50% lower overall project costs compared to the traditional design
- More room for trucks to maneuver
- Shorter construction schedule
The first DDI in the world was built in Versailles, France. Other DDI’s are currently under study at the Ontario Ministry of Transportation, the Oregon, Virginia, and New Mexico Departments of Transportation, and the City of Baltimore, Maryland.
However, the first in the United States was built by MoDOT in Springfield, Mo. MoDOT is also working on a DDI at the I-435 and Front Street exit.
For more information, or to submit a comment, click on the links below.
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