Missouri Department of Transportation photo shows the diverging diamond interchange, the first in the U.S., at I-44 and MO 13 in Springfield, Mo.

A new type of interchange could have drivers thinking they’re in the UK if it ever spreads across the States. It has the potential to keep traffic moving more quickly in and out of freeways while reducing left-turn conflicts.

It’s called the diverging diamond.

The principle behind it is to flip the direction of traffic on the surface street before it passes over or under the freeway. Using only two standard signalized intersections, the two travel directions on the surface street cross each other before and after passing through the interchange. It looks like left-hand drive.

While flipped, they allow for unimpeded left turns – there is no longer any oncoming traffic – both onto the freeway entrance and off of the freeway. Once traffic returns to right-hand drive, the other ramps allow unopposed right turns on and off the freeway.

Watch this computer simulation of how the diverging diamond works:

This is a very rare type of interchange. According to the research I did, there is only one currently in use in the United States, in Springfield, Mo., at Interstate 44 and MO 13. It is so new I was unable to find any online aerial mapping sites that show it in place.

I did find out, however, that the Colorado Department of Transportation considered the diverging diamond concept for its upcoming ambitious reconstruction of the congested interchange of the Sixth Avenue Freeway at Wadsworth Boulevard in Lakewood.

During the Environmental Assessment on the project, CDOT and its consultant CH2M Hill took a look and then eliminated it, the main concern being that traffic volume on Wadsworth and plans to widen it to six through lanes would lead to too much driver confusion during the crossover.

Here’s what the assessment said about it:

“Diverging Diamond Interchange; rare interchange type that would remove left turns in the intersection by requiring Wadsworth drivers to briefly cross opposite lanes of traffic at two crossover intersections; maintains off-ramp and frontage road in NE quadrant.

“Feasible and Prudent? No. Not prudent. Does not meet purpose and need for improved capacity on Wadsworth. Drivers are not accustomed to crossing opposing traffic, and they would likely slow down due to their uncertainty. Crossing in front of opposing traffic (even though opposing traffic is stopped) violates expectations.”

If the tryptophan in your Thanksgiving turkey isn’t enough to put you to sleep in your La-Z-Boy recliner today, you can read the entire Environmental Assessment on the US 6/Wadsworth project here.

However, the Missouri Department of Transportation has posted photos of the Springfield interchange on its Flickr account. Here’s the slideshow of it.

And here is a video that MoDOT put together showing the interchange from the air. Popular Mechanics just named the Springfield interchange design one of the “100 fastest, biggest, safest, greenest and most powerful innovations of the year.”

Missouri Department of Transportation video

Should this be used in Colorado? I can think of a few interchanges on Interstate 25 where I would have liked to see it tried, where CDOT has been replacing bridges over I-25 in Adams County, or maybe some in the Springs where a lot of I-25 work has been going on.