I have constructed a technology demo Blue Ice Hyperloop next to the road in the North-East corner of the road system. (North of the Museum, near the Colour Wheel.)
It goes as far as I was able but I ran into an amazing waterway tunnel that belongs to someone. I didn't realize anyone was north of there, tbh!
Anyway, go test it out. It allows for frankly ludicrous overland speeds but sadly does not allow for any kind of level change.