Chicago has a gated middle 2-lane express lane in the freeway. Gates go up on one side to allow traffic through, depending on traffic conditions, to force it one-way.
What I've never been sure about is how they guarantee no one is still traveling in the wrong direction at transition time
Mostly cameras. However they do have someone actually drive the lanes (I believe it’s usually during the mid-day turn) at least once a day to make sure the road is completely clear (debris, etc.)
What I've never been sure about is how they guarantee no one is still traveling in the wrong direction at transition time