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
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.