The Detroit Greenways initiative has been working hard to develop an “inner circle” greenway to allow non-motorized transit around the entire city. Little did we know that this was similarly proposed Around Outer Drive in the 1915 Preliminary Plan of Detroit by Herbert Bennett.
DETROITography 
Very cool. I believe that’s Outer Drive and Grand Boulevard. The Detroit Terminal Railroad was very active then and I can’t imagine they envisioned it being abandoned for a bike/walk trail.