Given the heavy (and ongoing) snowfall, Metro is only operating rail service in select underground locations, in order to prevent trains from getting stranded as accumulating snow makes it difficult to maintain contact with the third rail, and also to use existing tunnels to keep rail cars dry and operable, rather than buried in snow and exposed to the elements in Metro’s rail yards.

The adjusted service map looks like this:

Metro's snow map. Image from WMATA.

Riding the trains today, the service is essentially single-tracking in the underground portions of the system.  The segments of each open line in the middle have both tracks open, with each line essentially having two trains to cover the entire length of a line – they shuttle back and forth on a single track, passing each other on the double-tracked stretch in the middle.

Waits for the trains are long, and as is usual during single tracking operations, the PIDS aren’t all that reliable for train arrival times:

PID at U St, during snowpocalypse

In the single-tracked areas, the extra track is being used for train storage so that there are rail cars ready to enter service as soon as tracks are cleared:

Storage train riding out the storm at U St.

Metro did a good job of getting the system up and running again after the December 19th storm, opting to prepare the entire system for Monday’s rush rather than restore service immediately.  They’ll likely do the same this time around.