I do think these high-capacity, self-driving-only tunnels are a great idea in dense areas, but the tunnels and the self-driving bits are the easy part. The har

I do think these high-capacity, self-driving-only tunnels are a great idea in dense areas, but the tunnels and the self-driving bits are the easy part. The hard part is going to be the "vehicular multiplexing" that will be required on both ends to take a dozen or so lanes of traffic and squeeze them down into a single, compact, non-stop stream of vehicles through the tunnel. Otherwise, if you can't get ultra-high utilization out of these tunnels than they're really nothing more than a subterranean version of taking your personal helicopter to work.