I need to get the photographic evidence that supports this, but in a word: no. The reason why is that the stream doesn't go underneath the cycleway, but instead goes parallel to the now-abandoned section of cycleway in the same culvert. The cycleway then crosses the stream via what I mapped as a ford (there's no bridge, it just goes right into the stream, hence why I mapped it as a ford) to continue south as mapped. I mapped the abandoned section of cycleway as such, which is why it doesn't show up in OSM's rendering, but does show up in editors like JOSM. That's also why I mapped the practical altenate route as "Greenbelt Bikeway (detour)."

I documented this in my user diary entry entitlted "Greenbelt Bikeway Edits" on 11 April 2020, which you can find here: https://www.openstreetmap.org/user/ExpresswayDave/diary/392694