Originally Posted by blueDC
In the meantime, if they reduce enough blue line trains through Rosslyn and make it up with orange line trains, they can send more trains out from Vienna and Tysons (when completed) without impacting the current orange line schedule through the tunnel (which still leads to overcrowded trains as it is). Eight car trains will provide another duct tape's worth of relief. Sooner or later, another underwater tunnel will be needed. Likely under Georgetown?
If I remember correctly, the present tunnel under the Potomac is only one track and that's already a choke point with all the Orange and Blue trains during rush hour. What I read wasn't clear about how Metrorail might re-route Blue trains to the Yellow Line bridge across the Potomac. A majority of Virginian commuters who currently board the Blue Line in the mornings work in Northwest DC so they'd need to transfer at L'Enfant if their Blue trains take the Yellow Line bridge. Also, there'd need to be maintained a reasonable level of service to Arlington Cemetery.
My guess is also that any new tunnel would be at Georgetown. DC's a different city now and Georgetowners are really pining for a Metro station to the point that many of the merchants said they'd help pay for it, according to the Post a while back.