Quote:
Originally Posted by ardecila
But as orulz pointed out, horrendously expensive in a tunnel environment. You're installing, maintaining, and running cable between many complex and sensitive pieces of equipment, all in an extremely harsh environment subject to noise, vibration, moisture/flooding, vermin, etc.
If you can put all that tech in the vehicles themselves, then all installation and maintenance of those systems can be done above-ground in a shop instead of down in an active tunnel. That's a big if; I have to imagine the constrained sightlines of a tunnel will make truly wireless detection very difficult. At the very least it will require robust and redundant sets of wireless repeaters so a message can be carried down the tunnel from vehicle to vehicle.
Also the elimination of true stations removes a huge expense. A station cavern with elevators, escalators, etc costs hundreds of millions to build underground. An elevator shaft and the structure to connect it into the tunnel should be cheaper. For a point-to-point shuttle system like the O'Hare proposal without intermediate stops, you just need to build inclines or elevators at each end up to the surface, and all the passenger facilities can be built in a traditional, above-ground structure.
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I suspect that they will not use wireless anything. I suspect that they will use autonomous vehicle tech (lidar, sonar, even cameras) and operate based on line-of-sight. They will have to make their tunnels very straight, and slow down tremendously around curves, to overcome this problem.
Perhaps it will be possible to do ultrasonic rangefinding around curves by reflecting the sonar pulses off the walls, in which case this is mitigated somewhat. But this technology would have to be purpose-built and does not leverage economies of scale with AV systems already under development for cars.