MARC/VRE run-through

west point wrote:Not going to happen until all 4 tracks are fully operational from 1st street to ALX

True, it's early days yet. We need four tracks from ALX to L'Efant Plaza, so two can be passenger rail. Yes, we need the bridge as well.

But MARC to Alexandria (with a stop at Crystal City) can't come fast enough.

Apparently, a new FBI building may goose this process: WJLA.com

Maryland transportation officials seek input on extending MARC train service a day after FBI HQ announcement

Maryland Transportation Officials took to social media seeking input on extending MARC commuter rail service to Alexandria, Virginia.

It may not be a coincidence, because that would directly connect northern Virginia FBI employees to the Greenbelt station and the new headquarters.

Run-through service would require lower level tracks, much like the through Virginia Regionals and Florida and Carolina service.

Through MARC service to Philadelphia is already possible: there were a Maryland DOT (prior to the Maryland MTA) sponsored train, the Chesapeake, a through daily train between 30 Street Station and Washington Union Station
in the late 70s.

You’re assuming VRE equipment. MARC equipment will have no issues. It runs both high and low block.