"Diverging Diamond" Interchange at Dorsett and 270 Has Motorist Driving in "Wrong" Lane
The intersection is called a "Diverging Diamond" -- a name presumably stolen from a 007 book that never was. And, like a James Bond thriller, the intersection has motorists briefly driving on the British side (ie. left side) of the road as they navigate though the interchange.
It's all very confusing. But, according to MoDOT, will ease traffic congestion and make the interchange safer.
Here's a video tutorial of how the Double Diamond works...