I've seen this in action even on a pretty long merge segment for a lane reduction. It's a feedback loop of sorts, lots of people zoom up attempting to merge at

I've seen this in action even on a pretty long merge segment for a lane reduction. It's a feedback loop of sorts, lots of people zoom up attempting to merge at the last possible moment and bypass the line of people that are slowing down because people further ahead were zooming up and trying to merge at the last possible moment.