From what I've read (I think there was discussion on HN about it a few months ago?), it's not only the gauge. The entire system was a 'clean sheet' design, made

From what I've read (I think there was discussion on HN about it a few months ago?), it's not only the gauge. The entire system was a 'clean sheet' design, made by aerospace engineers. Everything is totally different from what you'd expect in any normal (heavy, light, subway) train.