I can think of a few double-decked roads in the city (such as under elevated portions of the FDR drive, and beneath elevated subway tracks in the outer boroughs) but nothing like what’s depicted in this drawing. It’s an interesting concept. Are there any major cities with double-decked sidewalks along the roads?
DOUBLE-DECKED STREETS FOR LOWER NEW YORK: Department of Public Works Has Made Plans for Elevated Sidewalks and for Tunnels to Relieve Congestion. (PDF)
From August 6, 1911