I understand and agree with the low probability of accidents.The length of the tunnel (short), use of EVs (no tank of hydrocarbons to burn), format (diameter and single lane only allow for a sideswipe with the wall), telemetry (low probability of an accident), and system control (cars can reverse from an accident) make crossover/ escape tunnels unnecessary for the Vegas setup.
Longer tunnels could incorporate crossovers, though many of the same points apply.
However, still accident probability must be taken into account.
And we have learned from the past that an accident may lead to reactions in panic from people, especially in tunnels.
So yes, they can reverse the car from the situation, but it is not difficult to see the possibility that that will be blocked by someone who in panic collided with the car behind.
Also emergency services need to be able to access the place of accident quickly.
Probably from the other side, when all cars in front have moved away?
Anyway, I do not know the risk calculations, but just one tunnel tube and no extra shielded way to flee gives me a creepy feeling.
Creepy feelings are not good guidance in itself, but should and I hope will have lead to risk investigation and when necessary risk mitigation.
@mongo The tunnel doesn't seem short to me (I know, it's relative..). Do you know how telemetry has been applied?
(background: I am a civil engineer, MSc from Delft University of Technology, have heavily (and heavenly ) invested in TSLA since 2013 and find this an interesting case ).