One of the many reasons that I travel is to see transportation facilities in different places, ways in which cities have made active transportation and transit better, or worse. I’m in Philadelphia at the moment, and one of the features that has been implemented is…

These sidewalk-level separated/protected bikeways are on several blocks of Market Street, the main east-west street in Philadelphia. These are new, and were under construction during my last visit a year ago. NACTO calls these Raised Protected Bike Lanes, with designs on the Separating Protected Bike Lanes page (scroll down for this design section).
These bikeways are visually distinctive from the adjacent sidewalk, composed of different materials and colors, red brick for the sidewalk (many sidewalks in Philadelphia are brick), grey granite for the separation, and black asphalt for the bikeway. NACTO recommends a tactile warning delineator (TWD) between the sidewalk and bikeway. The granite separator and change of texture may or may not meet this criteria for visually impaired people. Though
Philadelphia downtown has a significant bicyclist mode share, but it mostly seems to be on the north-south arterials and collectors, not on east-west streets. But this may be an artifact of the time of day I observed. It has a wide variety of bike facilities: traditional bike lanes, vertical delineator ‘separated’ bikeways, two-way separated bikeways (cycle tracks), parking protected bikeways, bikeways along transit islands. I don’t know the criteria, but I suspect that available roadway width is a determinant.
Sacramento is proposing a sidewalk-level bikeway (2-way cycle track) on H Street between 9th Street and 10th Street, at City Hall. I believe the design is for paint on the existing sidewalk, not reconstruction of that section. It will be interesting to see if this design works.