A congested interchange in the midst of a heavily traveled industrial, commercial and residential area received a major overhaul when it was redesigned in 2013. The previous diamond interchange at I-270 and Roberts Road in Columbus, Ohio was transformed into a Diverging Diamond Interchange (DDI) – an emerging and cost effective roadway solution designed to improve safety, reduce crashes and ease congestion. It is the first DDI in the state of Ohio and the 23rd in the United States.
The former interchange had geometric design deficiencies and was plagued with frequent congestion-related crashes. The Ohio Department of Transportation (ODOT) looked to Burgess & Niple’s (B&N) roadway design expertise to identify and design the right fit for the interchange.
B&N proposed a DDI as a solution that could fix the geometric issues as well as handle the high demand volume of traffic – including a large amount of truck traffic that drives area commerce. Traffic modeling and analysis indicated it could safely move the highest volume of traffic and be built for the lowest cost compared to other alternatives evaluated. A DDI is designed to be safer, more efficient and more cost effective than traditional diamond interchanges.
- Safety: By eliminating left turns that cross opposing traffic like those at conventional intersections, the number of potential conflict points is reduced by 42 percent in a DDI compared to a traditional diamond interchange. The number of crossing conflict points, typically resulting in the most severe crashes, is reduced by 80 percent.
- More Efficient: The I-270/Roberts Road DDI moves significantly more traffic than a traditional diamond interchange and can accommodate traffic volumes that exceed design year estimates. This is accomplished with improved signal operations that eliminate left-turn signal phases.
- Cost Effective: The I-270/Roberts Road DDI was determined to be about 25 percent less expensive to construct and moves traffic more efficiently than the other alternatives evaluated. The DDI also was the only design option evaluated that preserved two existing bridges over I-270 and could be built within the existing right-of-way, which significantly lowered the construction cost.
Serving more than 100,000 users daily, the I-270/Roberts Road DDI includes unique design features, such as dual left turn movements for large trucks, and it is the first DDI in the country with dedicated bike lanes.
B&N provided traffic forecasting, preliminary engineering, assistance with stakeholder and public involvement, and final design of the interchange reconfiguration. The DDI was built within the project budget and completed slightly ahead of schedule in October 2013.
During comments at the DDI ribbon cutting ceremony, ODOT District 6 Deputy Director Ferzan M. Ahmed stated, “This is not only an innovative solution in terms of engineering, but it’s also an innovative solution in terms of traffic management.” Ahmed noted that the more efficient interchange design is good for commuters, commerce and local businesses. “Traffic is going to move so much better with this Diverging Diamond Interchange in place.”
The American Council of Engineering Companies (ACEC) of Ohio presented the project with an Outstanding Achievement Award in the 2014 Engineering Excellence Awards.
The Central Ohio Section of the American Society of Highway Engineers (ASHE) presented the DDI with two awards: the 2013 Outstanding Highway Project Award and the 2013 Peer’s Choice Award. The project received an Innovative Transportation Solutions Award from the Columbus, Ohio chapter of the Women's Transportation Seminar. The American Council of Engineering Companies (ACEC) of Ohio presented the project with an Outstanding Achievement Award in the 2014 Engineering Excellence Awards.