So for each access shaft, you'll need 1000m of parallel tunnel to get vehicles on and off the primary tunnel. And 0.9s separation doesn't leave much space for error.
If you were to run buses full of people in this thing, it becomes a railway, and you'd need a full signalling system and safe separation between "trolleys".
240 departures/hour, besides being plainly impossible for the system the @boringcompany is proposing, would only give 6000pax/hr/dir, which is better than a bus or tram but still a sixth of the capacity of a metro rail system.
Suffice to say I'm struggling to see why people aren't loudly and vigourously ridiculing Musk for inventing **checks notes** a way to bury a lane of traffic underground 💩