[dzhiurgis]

> put them on rails to reduce friction

Good luck climbing hills. A lot of systems like these moved away from rails onto rubber tires.

Rapid bus is probably best combination. Yes it will never match the throughput of rail, but it's vastly cheaper.

[maximilianthe1]

Have you seen hills in NYC or (most of) other major cities? Also, the solition is deeper stations under hills & escalators.

[dzhiurgis]

So solution is to make from 3x more expensive to 5x more expensive?

And don't get me wrong, some places in US (with extreme density) should do this. Personally it's not the places where I'd ever want to live ever again lol.

[rangestransform]

deep stations have a significant impact on travel times, it takes well over 5 minutes to surface from the deepest stations in Barcelona

[dangus]

Trains can have rubber tires (Paris metro)