Interchange Designs - I-10: SR 85 to Verrado Way Improvements

New Diverging Diamond Interchanges (DDI) at Miller and Watson roads

The interchanges at Miller and Watson roads will be reconstructed in a diverging diamond design (DDI) as part of the improvements to I-10 between SR 85 and Verrado Way.  A DDI is a diamond interchange on which the two directions of traffic on the cross street (above or below the freeway) cross to the opposite side on both sides of the bridge at the freeway. DDIs can reduce the number and severity of crashes compared to traditional diamond interchanges, while reducing traffic congestion. They also provide an excellent opportunity to integrate multimodal facilities for pedestrians, cyclists and transit into the interchange. They can be more cost effective to build, and there are fewer impacts on the local community during the construction process.

Following an intensive study of the design by the Federal Highway Administration (FHWA), the first such intersection in the U.S. was completed in Springfield, MO in 2009. In the United States, more than 90 DDIs have been constructed in 29 states since 2009. The design has increased in popularity because of safety, operational and cost benefits.

Miller Road Traffic Interchange Design

Miller Road Traffic Interchange Design

Watson Road Traffic Interchange Design

Watson Road Traffic Interchange Design

Diverging Diamond interchanges

If you’re curious to see how a DDI works, watch the Diverging Diamond Interchange video from the Illinois Department of Transportation (IDOT). Recently IDOT constructed a DDI at I-88 and Route 59 near Chicago. This DDI’s design is similar to the DDIs that will be constructed at Watson and Miller roads as well as a DDI under construction at I-17 and Happy Valley Road.