True, but I think you undersell the benefit of this: > This allows people to reroute or exit the highway before the traffic jam, reducing the burden on the bot

True, but I think you undersell the benefit of this: > This allows people to reroute or exit the highway before the traffic jam, reducing the burden on the bottleneck. Many of those people could have already been intending to exit the highway earlier. Because of the back-up, their journeys are slowed way down unnecessarily. And then you get compounded effects - the highway backs up past another entrance, causing that feeder road to back up past an intersection... In the worst case you end up with gridlock. I'm not arguing that zipper merges are magical either, but they can definitely have a significant impact.