About the Manhattan Bridge   See Acps I read the history site on the W train page It says When all four tracks on the Manhattan Bridge were restored on February   the W was changed to its final service pattern as a weekday local between Whitehall Street  South Ferry and Queens This means the W was local and the N was express Thats when the Manhattan Bridges north tracks reopen for the B and D trains Read more about the service history of the B D N Q and W train pages so you can get a better understand you meanie D