Bentley Recognizes TWM for Innovative Diverging Diamond Interchange

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October 2012 – TWM’s work on one of the first Diverging Diamond Interchanges in Illinois, at I-57 and Morgan Avenue in Marion, has garnered the firm a nomination for the 2012 Be Inspired Awards, sponsored by Bentley Systems, the maker of a number of engineering software programs used by the firm.  

TWM studied and is now designing the new interchange for IDOT District 9.  A DDI is different from other diamond interchanges in that each direction of traffic on the freeway overpass briefly travels on the left side of the road.  The advantage is the ability to remove left-turn movements from the intersections of the ramps and minor roadway creating a free flow condition.  It also reduces signal phasing to two phases, resulting in a more efficient flow of traffic.  In this instance, the DDI was shown to provide greater capacity and lower cost than alternatives.  The DDI is believed to have debuted in Europe, and is now making its way to the United States, where only a few of the innovative interchanges are open to traffic.  Several are currently in design, including one in northern Illinois.