New ‘diverging diamond’ interchange is a first for KC area

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– or, right away — to Interstate 435 and Front Street.

Missouri highway officials on Thursday cut the ribbon in east Kansas City on a new $8.1 million “diverging diamond interchange” based on a design pioneered in France.

The design represents the Kansas City area’s first use of the concept, which engineers believe will increase vehicle flow and efficiency at an especially busy intersection. Several more are proposed or under construction.

The design routes both directions of traffic to opposite sides of the road just before the interchange. The crossover permits drivers to turn left without stopping at another light or turning in front of traffic.

“Our engineers were looking for a better solution to redoing a very congested and crowded interchange,” said Steve Porter, MoDOT spokesman.

“One of our folks had read about a ‘diverging diamond interchange’ being used in Versailles, France. But they weren’t using it with a highway.”

The Front Street version does.

“This kind of interchange functions well when you have a lot of left-turning traffic, which is exactly what we had at this interchange,” said Matt Killion, MoDOT area engineer.

The new interchange became largely operational last fall, Porter said. Much concrete work remained, however, and the bulk of that was wrapped up recently.

Thursday’s ceremonies included representatives from employers near the interchange, such as Bayer CropScience. State highway officials, Porter said, worked with area employers who, in turn, often allowed employees to work flexible schedules during construction or report during off-peak hours. Construction began in April 2011.

Initially, the diverging diamond design for I-435 and Front Street was not only the first in the country but the entire Western Hemisphere, according to MoDOT.

However, deadlines for the new Christopher S. Bond Bridge intervened and, in the interim, a diverging diamond project was completed in 2009 in Springfield, Mo., at Missouri 13 and Interstate 44.

“So another MoDOT district got the diverging diamond first, but we are glad it remained in the family,” Porter said.

The I-435 and Front Street design is nevertheless unique, Porter added, as it is the first such diverging diamond to route traffic under an interstate. The Springfield design goes over the interstate, he said.