The purpose of making traffic flow smoother is that it'll push out the point where flow breaks down and you can extend the zone of (relatively) uncongested operation with higher vehicle throughput. Smoother flows leads to fewer abrupt stops and rear-end accidents that make the wait even worse. (Cars in a 'beautiful line at 35mph' behave differently from stop-and-go and for instance a fleet of self-driving cars would make the highest throughout, and extreme example)
As for late merging, evidence shows that it's more efficient in congested areas and by reducing the line, you help prevent spillover to other areas and importantly accidents due to conflicts. I can see one super suboptimal situation where a car completely stops to change lanes (into a stopped/slow one) due to bad flow, resulting in more than just a 2 second impact on one lane. MN signs say "use both lanes / take turns" and dynamically adjust based on traffic conditions. In LA, the "zipper merge" seems to be standard for most construction zones in traffic jams, with the only distinction being where you merge in the last 200 feet
As for late merging, evidence shows that it's more efficient in congested areas and by reducing the line, you help prevent spillover to other areas and importantly accidents due to conflicts. I can see one super suboptimal situation where a car completely stops to change lanes (into a stopped/slow one) due to bad flow, resulting in more than just a 2 second impact on one lane. MN signs say "use both lanes / take turns" and dynamically adjust based on traffic conditions. In LA, the "zipper merge" seems to be standard for most construction zones in traffic jams, with the only distinction being where you merge in the last 200 feet
http://www.dot.state.mn.us/trafficeng/workzone/doc/2004DLMS-... http://www.dot.state.mn.us/trafficeng/workzone/doc/When-late...