On a much smaller scale, Copenhagen is reviving the idea of a grade-separated bike "highway" in at least one place. A major bicycle commuting route currently go

On a much smaller scale, Copenhagen is reviving the idea of a grade-separated bike "highway" in at least one place. A major bicycle commuting route currently goes through a complex congested area (with a bunch of 90-degree turns, pedestrian cross traffic, canals, and even a staircase at one point), but will from next year bypass it on a 1/4-km overpass: http://politiken.dk/ibyen/nyheder/gadeplan/ECE1594066/koebenhavn-faar-235-meter-lang-cykelsti-i-foerstesals-hoejde/ http://politiken.dk/ibyen/nyheder/gadeplan/ECE1594066/koeben... In the rest of the city the goal is to string together something more like arterial bicycle roads, though, rather than fully grade-separated highways.