Unique Diverging Diamond planned for revamped SR-265/SR-62 Indiana interchange
Design saves $66 million for Ohio River Bridges Project
LOUISVILLE, Ky. - (December 22, 2009) A major cost-reducing reconfiguration of the SR-265/SR-62 interchange has been unveiled for Clark County, Ind. It's a Diverging Diamond, a unique concept for the U.S., but one that has been used in Europe for many years.
A Diverging Diamond is a more efficient design than a full cloverleaf because it has a smaller footprint, meaning less right-of-way land will be purchased. It also allows the use of existing overpass bridges.
"This design is cutting the cost in half," says Kevin Hetrick, the project manager of the Ohio River Bridges Project (ORBP) for the Indiana Department of Transportation (INDOT). The preliminary estimate from the Environmental Impact Statement (EIS) was $118 million. The new estimate based on the Diverging Diamond is approximately $52 million.
"The Diverging Diamond is also safer for motorists and it creates more green-light time, meaning traffic flows through the interchange faster and smoother," adds Hetrick. "Everything about it is a win situation."
So how does a Diverging Diamond work?
For U.S. drivers, it's difficult to envision because vehicles crisscross and travel on the left side of the highway instead of the right for a brief time. Barriers keep traffic separated. Visual screens are also used. "It's designed so that motorists don't even know they're driving on the opposite side," says Hetrick.
Press play to see an aerial view of the Diverging Diamond interchange planned for SR-265/SR-62.
This video has been provided by the engineers at Burgess & Niple, Inc.
Two traffic lights are needed. Each has only two phases – stop and go. There are no left turns at the lights, meaning motorists get more green time. All left turns are free flowing and never cross traffic.
The Diverging Diamond improves safety because it has only 12 conflict points (places where traffic crosses or merges). That compares to a normal diamond interchange which has 30 conflict points.
Only one Diverging Diamond exists in the U.S., which was opened to traffic in June, 2009 in Springfield, Mo. (see stories by Popular Science and NPR at http://www.popsci.com/bown/2009/product/diverging-diamond-interchange and www.npr.org/templates/story/story.php?storyId=120403340). Another is under construction in American Fork, Utah. Others are planned in several states.
The one planned for Southern Indiana near Utica has been approved by the ORBP's Bi-state Management Team and the Federal Highway Administration.
SR-265, which currently ends at SR-62, will eventually extend to the new East End Bridge. In addition to the SR-265/SR-62 interchange, the five-mile, six-lane stretch of highway will feature a full interchange at Old Salem Road, improvements to Utica-Sellersburg Road near the new highway and direct access to 265 from Port Road.
Engineering designs are now 30% complete. A construction date has not been set, but once construction begins, it's expected to take two to three years to complete.
The Ohio River Bridges Project is the third-largest transportation project in the country and calls for building two bridges in metro Louisville and the highways leading to them, including a reconfiguration of the Kennedy Interchange (a.k.a. Spaghetti Junction) in downtown.
Click thumbnails to view larger image.