I'm a planner, and I still find myself going "WTF?" at various traffic management practices.
One of them is the way lanes are added to carriageways on limited access highways. In Ohio, at the point a limited access highway widens from two to three or more lanes, the new lanes are added not on the left, but from the continuation of entrance ramps on the right as a new traffic lane.. Whenever a limited access highway transitions from four lanes to three or three lanes to two, it's not by merging the leftmost traffic lane into the remaining leftmost lane, but by turning the rightmost traffic lane into an "exit only" lane for the next upcoming exit. This forces through traffic in the rightmost lane to merge left into the remaining traffic lane, causing confusion by drivers unfamiliar with the road, and inevitable congestion.
So, those familiar with traffic management: why do they do this?