[Qubert]

My personal proposal would be making the Silver line run express under I-66 after East Falls Church then under K st with stops at Foggy Botton, Farragut, McPherson Sq, Mt Vernon Sq, then turn south under Captial St NW, then turn down Massachusetts to stop at Union Station (thus relieving the Red Line), continue south down 2nd St NE/SE and then turn down L st SW with stops at Navy Yard and Waterfront, then take over the Yellow Line bridge and replace the Yellow south of L'Enfant to Huntington.

Pros:

Creates Metro's first express line for some of the farthest reaches of the system. Orange line pax from Vienna benefit through the transfer at East Falls Church and Silver line pax wanting Arlington can switch to Orange.

The Green Line is now totally seperate, allowing a tremendous increase in service to the southern sections.

Relieves the Red by having Union Station pax be able to access the CBD via the westbound Silver.

Gives pax in Alexandria/Springfield/Crystal City a direct connection to Union Sta and Navy Yard