Riverside Drive overpass at 96th Street. This is another of Moses' Grade Crossing Eliminations, because before the Henry Hudson Parkway was built, 96th Street didn't have any reason to go across Riverside Drive. Plus, the bridge is made made of concrete (the WPA's favorite building material).

References:

1. NYC Parks Dept press release of February 27, 1935: ”At 96th Street there will be a second grade crossing elimination.” [in addition to the 79th Street one].
2. New Deal Assistance in NYC Parks Department Projects, 1934-43.