Why were THOSE two never built?
And... EAST of U Street-Cardozo, assuming there to be enough tangent easement there, the pocket would end up being used to turn trains back at Shaw-Howard Univ. as per standard Metrorail practice (the pocket is used to store trains outbound of the station, not inbound... which is why Yellow doesn't go to Shaw, nor did the Commuter Shortcut go to Dupont Circle).
And I remembered about the "double-decker" tunnel under NH Ave. Creative design indeed. I'd like to see them do that again. Outbound's the top layer, yes?
And... still to this day, the MOST impressive bit of WMATA construction to me would be the two bi-level islands... Pentagon and Rosslyn Stations. I've seen both with my mother, and for some reason, she finds Pentagon's design to be somewhat more asthetically pleasing than Rosslyn... aren't they identical, save for the side the "next train destination"* panels are on, and the routes serving them?
* "Next Train Destination" panels: Illuminated by an (assumedly) fluorescent bulb behind them. Triggered about the same time as the flashing platform lights (Train is 2700' from station). Colored panels with black lettering light up to show where the next train is going. Such as at Stad-Arm, where Orange shows New Carrollton, and Blue shows Addison Road. Located (in Stad-Arm and L'Enfant Plaza) above the tunnel portals at the outbound end, or at whatever end leads towards the split. Existence confirmed at Rosslyn (Blue/Orange), L'Enfant Plaza (Green/Yellow), and Stadium-Armory (Blue/Orange). Supposedly also exist at King Street and Pentagon (Blue/Yellow). (Oren, have you any pics of them aside from the Plaza and Stad-Arm? (I've been trampled at both enough to remember them)). ONLY exist at these stations to aid in identifying the correct train because if you get on the wrong train, you can't just hop off at the next stop to change trains.
BTW, John... have you any idea where else there's enough tangent easement to add pockets?