The new first-in-the-USA Diverging Diamond Interchange, which opened June 21 at Route 13 and Interstate 44, initially has achieved its goal to move more traffic in less time through the busy northwest gateway to Springfield.

"It's doing exactly what we wanted it to do," said District 8 Project Manager Don Saiko, who helped adapt the European design for Route 13/I-44.

"Nearly everyone I've talked to has said traffic really is flowing smoothly," Springfield Mayor Jim O'Neal said at a July 7 ribbon cutting. The event was presided over by Springfieldian Jim Anderson, who recently completed eight years of service on the Missouri Highways and Transportation Commission.

The city of Springfield split the cost of the $2.9 million project with MoDOT.

Under the new Diverging Diamond Interchange configuration, the opposing lanes of Route 13 (Kansas Expressway) criss-cross at traffic signals at the ends of the bridge over I-44. Crossing the bridge, oncoming traffic is on the right, separated by concrete barriers with a pedestrian walkway between the barriers. This gives left-turning vehicles on Kansas Expressway a "free left" turn, without backups, onto the I-44 on-ramps. At the same time, through traffic continuing north or south on Kansas Expressway travels more steadily through the interchange.

Saiko credits District 4 for pursuing the Diverging Diamond design in Missouri as early as 2005 when District 4 Project Manager Susan McCubbins, now retired, presented the design at a statewide meeting. She said her design team found the DDI had been working for 20 years at an interchange in Versailles, France, and worked with the Federal Highway Administration on a simulation.

Saiko, who remembered the presentation, concluded the Route 13/I-44 interchange would be a good place to use the DDI design. The bridge over I-44 did not have to be replaced but could be repaired. The project could be done in six months, not 1-1/2 years for a more standard interchange rebuild. By getting in and getting out that quickly, safety would be enhanced and the public would have the improvement sooner rather than later.

District Traffic Engineer Joe Rickman, who has overseen several additions or changes to the signing and striping since the retrofitted interchange opened, said the design is functioning amazingly well, even during morning and afternoon rush hours.

"There's no reason to believe it won't have greatly improved safety," Rickman said, noting that the police reported only one crash on the DDI portion of the interchange in the first three weeks after its opening -- a rear-ender involving two vehicles exiting eastbound I-44 to go south on Route 13. No crashes have occurred where traffic is criss-crossing into the new DDI configuration.