Score another victory for traffic engineers who support wider adoption of free-flowing roundabouts at U.S. intersections.

“Mythbusters” has staged what just might be the ultimate transportation-geek showdown: An American four-way stop vs. an uncontrolled one-lane European roundabout.

Roundabouts are becoming more common in Portland (tragedy has given rise to plans for one in Forest Grove), but they’re far from mainstream.

But as I wrote in a 2009 column, the Wanker’s Corner roundabout at the juncture of Stafford and Borland roads in Clackamas County shows the benefits of removing traffic signals in favor of allowing a little chaos.

Uncertainty now breeds caution and mostly free-flowing traffic in what was once a congested crossroads.

Also, in roundabouts, crashes tend to be slower and involve rear-end collisions, versus more deadly side collisions typical at traditional intersections.

On “Mythbusters,” stars Jamie Hyneman and Adam Savage tested “the myth” that roundabouts are a triumph of efficiency in fighting traffic congestion.

Their verdict: It’s true.

It wasn’t even close to being busted.

During two 15-minute tests, 385 vehicles passed through the four-way intersection. During the same time period, 460 vehicles moved through the roundabout intersection.

So, the roundabout actually improved traffic flow by 20 percent, according to the test runs.

I can think of at least 10 intersections in the greater Portland area, including a few on Southwest Scholls Ferry Road and along the Beaverton-Hillsdale Highway, that are begging for a roundabout.

Watch the video for yourself:

Click image to play or go to http://www.wimp.com/testroundabout/