Racing at 127mph under a tunnel in LA [video]
youtube.com
youtube.com
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.
This video makes me think my earlier understanding was correct. It doesn’t look like the person is steering (and it would be quite dangerous to require them to). So how does this work?
Outside a video game, is anybody going to do better than 40mph in a tunnel?