Interesting! But presumably in this setup, one would experience both significant acceleration AND deceleration. Is there any static orientation that would minimize problems for both?
Well, sideways or rather upright (possibly in a seating position) is probably better but seems not very aerodynamic. I think those are the three possible orientations. But I mean are we seriously considering a transportation system where part of the journey is a black out/red out? The time gain by accelerating with 5g instead of 1g can't be that big (Maybe a few minutes at most?).
Edit: I'm not sure if there's an error in my calculations but with 1g acceleration it should take about 25s to get to 900km/h? That seems ok.
I agree with your calculations, but with an 1g acceleration for 25s, the train will travel a bit more than 3km, and getting to the end of the track (which is 3km according to the article) at close to 900km/h is unlikely to lead to a happy outcome.
If my math is right, in order to accelerate to 900km/h and decelerate to a stop again, all on a 3km track, requires acceleration/deceleration of a bit more than 2g.
Not proof of anything but notice rocket crew always face front.