RP: Two Tracks to Tartarus?

Sorry, I couldn't resist the (increadibly dorky) Highway to Hell reference. This is more of citywide (and really, just generally urban) issue, but Richard Layman (Rebuilding Place) has a really great piece on why Metro's two track system is a serious problem (main points: delays when anything goes wrong, major danger if we ever experience a terrorist attack, a limit on DC's capacity for latenight service because they have to stop trains to do track maintenance).