The Transport Politic often showcases unique and clever transit solutions visualized by the site's author, Yonah Freemark. Recently he looked into the WMATA system and made an interesting proposal: a separated Blue Line, and running along it, another investment, a so-called Pink Line. Though Freemark's plan would add invaluable capacity and connectivity to our system, I believe a similar vision could be achieved without building another costly Potomac Crossing. That's not to say we shouldn't, but perhaps a closer term solution might look more like this:
View Pink Line in a larger map
The existing Potomac crossing where the Yellow Line connects Downtown and Pentagon City is underutilized and ought to have it's capacity increased before another crossing is built. This alternative combines the cross-Arlington connectivity that Freemark envisions without the circuitous route back through Rosslyn. This investment could be increased even more if the Green and Yellow Lines could be separated downtown, which might prove cheaper than the Blue Line separation. Another advantage would be that this line could just be an extension of the Silver Line, which would eliminate the need for a new line color.
New track miles are most valuable in the core. Unfortunately, they're also generally the most expensive new track miles. But the benefits to the entire region are huge across the entire system, making it a worthwhile investment. And it's about time we started considering "the rest of Arlington" more a part of the core.