Driving on a Diverging Diamond Interchange

 

Driving on the wrong side of the road is normally reserved for trips to Europe, action movies and soon-to-be jail time.

But one of the most innovative new highway interchange ideas in transportation design has drivers doing just that, resulting in not only optimized traffic flow but also increased safety in several ways.

The Diverging Diamond Interchange (DDI), first introduced in the United States by MoDOT in 2009, increases both capacity and safety by removing traditional left-turn movements. As seen in the video above, each direction of traffic is shifted left, creating an “X” pattern that has drivers spending a short time on the wrong side of the road.

Because of this change, left-turning vehicles don’t turn in front of on-coming traffic and the number of points of conflict (where crashes are most likely to occur) are reduced from 30 to 18. Moreover, traffic speeds are slowed, signal timing is improved and it’s nearly impossible to go the wrong way in a DDI configuration, adding additional levels of safety and efficiency.

Add it all together and it’s easy to see why the design was chosen as one of Popular Science’s top engineering innovations in 2009.

Thus, despite its out-of-the-box nature, the DDI is emerging as a preferred option for traffic and transportation engineers — GBA included —when designing certain complex interchanges. Currently, GBA has three DDI designs in the works:

1. A brand-new six-lane DDI at 211^th Street and I-49 just in Peculiar, Mo.
2. A DDI at K-7 and 130^th Street as part of a complex redesign of I-70 and K-7 in Bonner Springs, Kan.
3. The modification of a current interchange at K-10 and US-40 in Lawrence, Kan., that will preserve an existing bridge while enhancing capacity for proposed residential and commercial development, including the University of Kansas’s “Rock Chalk Park” athletic complex.

For more information on the use of DDIs, check out information provided by both MoDOT and KDOT.