Following up on my previous comments about Metro expansion and a new Yellow line, I wanted to add some graphical representation of these ideas.

First, the current Metro system:

View DC Metro in a larger map

My plan includes the Silver line as currently planned and under construction, as well as my conception of the new Blue line (shown in teal) as well as a separated Yellow line (shown in Goldenrod), with separation from both the Green like through DC and from the Blue line through Arlington and Alexandria.  The new lines only are here:

View DC Metro Expansion in a larger map

Combine both the current system and the new plans, and you get this:

View Combined Metro Map in a larger map

Old tracks are in blue, new tracks in yellow.

Obviously, these maps have no stations (yet).  It’s safe to assume that where two lines cross, you’d want to have some sort of a transfer station there.  With new lines crossing (thinking specifically of the intersection of North Capitol and H St), you could have a brand new Metro Center-esque station, linked by tunnel to the current Red line stop at Union Station.

The purpose of putting these lines on these streets is merely to define the corridors and ensure some feasiblity in terms of potential rights of way and station areas, but they shouldn’t be considered concrete decisions.