Talk about a misleading title!

I don't know this structure, but I differentiate between a tunnel under a natural object--Lincoln Tunnel, Holland Tunnel, Ted Williams Tunnel, etc. and a crossing underneath a man-made object. There isn't enough in this photo to know whether what is likely a railroad track was built up or if this is a naturally occurring obstacle. Along the MetroNorth tracks in a fairfield County there are multiple structures similar to this startong just over the NY line, underneath elevated railroad tracks.

Most important is that CT has a pair of serious tunnels on the Wilbur Cross. The tunnel in this photo isn't particularly unique. .