The "Downtown" Circulator and Rosslyn, Virginia

The "K Street" Downtown Circulator bus route to Georgetown is part of the proposed cross-town streetcar route that would start at Minnesota Avenue and go west on Benning Road and H Street NE, connecting to Union Station, and providing service to the Convention Center and downtown, and then routing up K Street (and then M Street) to Georgetown.
Notice the similar painting schemes between the Downtown Circulator and the proposed DC streetcars? (Image from the streetcar section of the DDOT website).

Back in the streetcar days, this was the old 10/12 streetcar route, which went up through Georgetown, crossed the Key Bridge and did a turn around loop in Rosslyn.
The 10/12 line was abandoned in 1949. The green line on the bottom left of this DC Transit streetcar map from 1955 shows the stub of the streetcar route into Rosslyn, Virginia, with service provided by the 20 line. Image from Wikipedia, original source unknown.

Given the tunnel capacity issue for the blue and orange lines, I wonder if this kind of route extension to Rosslyn ought to be considered at some point for the streetcar and/or the Downtown Circulator, even sooner?

The DC Streetcar planning project is focused on transit strictly within the borders of DC proper (with the exception of proposals to run a streetcar line on Georgia Avenue that would cross the DC-Maryland state line and terminate at the Silver Spring Metro Station in Maryland. But maybe we need to be a little more broad minded...

As far as a streetcar is concerned, extending the line across the Key Bridge to Rosslyn would add a form of redundancy to the Blue and Orange lines (which desperately need more tracking capacity within the downtown DC core), and provide an alternative (not a replacement) for getting across the Potomac River.

If you ask me, adding under-river tunnel capacity should be included as part of the Dulles Corridor subway expansion project, which is thought of as a primarily Virginia project. But thinking in such constrained fashion is a mistake, as you can't add more trains and riders to a known capacity choke point (the Rosslyn-DC tunnel) without having "service degradation." And what if something happens to either the Yellow Line bridge over the Potomac, or the Blue-Orange Line tunnel?
From the "Talk about H Street" campaign produced by Kevin Palmer and Richard Layman. Image of the intersection at 8th and H Streets NE (c1940s) from the Leroy King Collection, curated by Lee H. Rogers.

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