When I approached the interchange of I-43 and Brown Deer Road, I had an advantage: I knew things were about to get weird. The driver in front of me, I suspect, did not; hence their last-second swerve from the swooping left-turn lane into mine.

Together, we were experiencing Southeastern Wisconsin’s new, and so far only, “diverging diamond” interchange. Opened after construction late last year, it’s meant to make left turns safer. Traffic on Brown Deer curves into what, under normal circumstances, would appear to be the oncoming lane.

Under the direction of multiple traffic lights, cars curve left, either making the turn onto the interstate or curving right again, past traffic and back onto Brown Deer Road. Overhead signage makes the unusual move simple to follow – and the left turns we

See Full Page