Metro’s “passenger information displays” (PIDs) are the digital signs in the stations that announce upcoming train arrivals. I wrote my own “Web PIDs” app using the Metro Transparent Data Sets API to show the same information on the web. The initial view of the application presents a menu of station names. Selecting one or more stations embeds their codes in the URL, which you can bookmark to return to the same view. You’ll see the station codes in the URL, like below:
The above link shows arrival times at Farragut North, McPherson Square, and Mount Vernon Square. WMATA uses 3-character RTU (remote terminal unit) codes.
The data comes from WMATA’s web services, specifically Method 5: Rail Station Prediction. Using AJAX, the displays are updated every 20 seconds. I display all the data returned by the web service; sometimes there are more than 3 lines of information for a display. The data isn’t reliably available at (or near) end stations, a problem I’ve experienced as a passenger with Metro’s own signs.
An option at the bottom lets you display both sides of the track together, as you would see outside the station’s entrance, or displaying each direction separately, as you would see on side-by-side displays on the platforms. Four of the transfer stations have overlapping lines: Metro Center, L’Enfant Plaza, Gallery Place, and Fort Totten. These stations will show two sets of displays when selected.