"Silver Line" is indeed the color Metro is talking about using, but
only after the line is extended past Wiehle Av, I think.
The PIMS would say in 2010:
ORANGE -- Wiehle Avenue -- 12 mins
ORANGE -- Stadium Armory -- 12 mins
ORANGE -- Westpark -- 6 minutes
(short turn trains)
In 2017 (no joke, that is the
timeframe, thanks Bush admin!)
ORANGE -- Centerville or West Falls Church -- 12 mins
SILVER -- Ashburn -- 9 mins
SILVER -- Tyco Road -- 6 mins (short turn from Stadium Armory)
ORANGE -- Centerville -- 3 mins
SILVER -- Stadium Armory -- 9 mins
SILVER -- New Carrollton -- 6 mins
ORANGE -- New Carrollton -- 3 mins
And between Tysons Corner and Falls Chrch, PIMS would read:
SILVER -- Tyco Road -- 12 mins (short turn outbound from Stadium Armory to Tyco Road)
SILVER -- Ashburn -- 9 mins
SILVER -- Ashburn -- 6 mins (short turn at Westpark inbound, no shared track w/ Orange line)
SILVER -- Tyco Road -- 3 mins
(shuttle from Centreville via Dunn Loring, using WFC yard lead)
This color coding would allow Metro to use the planned West Falls Church yard lead to Dulles
and also pocket tracks immediately east (Westpark) and west (Tyco Road) of Tysons Corner,
to provisde easily identifiable Silver Line "shuttle service" from Centerville to Tyco Road
(Tysons West) via West Falls Church yard, in the event of an Orange line extension to Centerville.
The Wiehle Avenue spur will be connected to West Falls Church yard by a new grade-seprated pocket track in the Dulles Access Road just north of WFC station, which is connected to the yard by an existing two-track spur, tho' not in the outbound direction, unfortunately. That would have to be built as part of the Orange line extension along I-66 to Centerville.