According to analysis from engineers, or Esther from a guy I used to work with who studied break waves for the state transportation board, less cars with larger gaps is better. That's why you see semaphores on highway entering ramps sometimes, ie 101 around SV or certain European big city inner highways.

This is a problem that can probably be solved someday with self driving cars collaborating to make highways huge coordinated conveyor belts.

Actually, this is a problem that is already solved by smart motorways in the UK (Europe too maybe?). They have a variable speed limit that dynamically changes according to traffic that stop brake waves happening.

Do you not have them in the US?

If my experience with smart motorways is anything to go by they seem to increase brake waves because there are often times that speeds get reduced significantly for arbitrary reasons that not everyone chooses to follow. You then get larger closing speeds which causes people to slam on the brakes.

Additionally the removal of hard shoulders is just dangerous.

Not only do we not have them, but I don't think I've ever read a freeway speed limit sign at all.

> I don't think I've ever read a freeway speed limit sign at all

Lol, why adopt the UK's variable speed limit when we have already de-facto reinvented the Autobahn....

Seattle adjusts the speed limit on one of their highways down to 45 or 35 during rush hour which increases the throughput as the cars can be closer together. Not sure if that has been picked up by other cities.