[VivaLFuego]

Is the flying junction west of Rosslyn station where Orange/Blue converge a Y junction or are all train movements possible? I.e. could one route trains from Franconia to Vienna?

Given the low peak flow currently contributed by the Blue Line at that point, I'm wondering if such a routing like that above could be run at much lower frequencies to make room in the tunnel for Orange+Silver, while running increased Yellow Line service as a branch split operation west of the river (i.e. make permanent the Rush+ concept).