GREENWOOD, Ind. (AP) — State highway officials hope to make Indiana the latest state to try a new highway ramp design that can lower construction costs and make travel easier.
The Indianapolis Star reports that planners with the Indiana Department of Transportation are discussing building a diverging diamond interchange along Interstate 65 in Greenwood, south of Indianapolis. A similar project is planned along Interstate 69 in Fort Wayne.
Diverging diamond interchanges crisscross east- and west-bound lanes to allow cars to enter highways without turning left in front of oncoming traffic.
"The downside is it's something new," INDOT engineer Susan Doell told the Star. "People are going to have to get used to it."
The design is safer than a more traditional cloverleaf-style interchange because there is a "lack of weaving and (a) big differential of speeds between the loop ramps and the through traffic," Gilbert Chlewicki, a Maryland engineer, told the Star. There are also signals that control traffic at both points where the lanes cross.
The interchanges would be the first of their kind in Indiana, but seven other states so far have built them. States that have adopted the diverging diamond design have saved millions of dollars. The design is more compact than traditional cloverleaf interchanges and tends to be cheaper.
Diverging diamond interchanges have also been proven to reduce crashes in some areas. A study shows that in St. Louis, the diverging diamond interchange showed a 38 percent drop in crashes with no wrong-way crashes.