On my way back to the TC on I-94 (spent the weekend celebrating Sinclair Lewis Days in Sauk Centre), smooth traffic came to a quick stop and go holdup. Eventually we saw a sign telling us the right lane was closed ahead, and we should merge left. All drivers were behaving accordingly. After driving much farther, it became obvious that the right lane was not closed at all. A big traffic slowdown occurred for nothing.
There was a signifier, but no signified. Yet we all behaved according to the dictates of the signifier.