the beltline on Atlanta comes to mind
I just looked it up and this is exactly what I mean by a separate location. Minneapolis has a bit of this too. I mean you could also use 3 dimensions space and put bikes up or down to resolve the core tension. All of these are of very limited viability so I understand from a pragmatic perspective why cities arent just doing this.
Yeah I think atlanta only got this as a freebie due to it being built on top of their abandoned rail road.
In europe there's also a great culture of bike /walking dirt only pathways too, but I agree its not very practical solution for cities