You can read more about the capabilities at the paid washdcsubway app.
This free version updates the screen every 60 seconds.
With the paid version you can:
o change the update rate,
o display WMATA maps,
o display Rail Alerts (e.g. single tracking events)
o display all the stations for a particular Rail Line (e.g. Blue Line) with the stations in the travel order.
If you like the free version, then for the price of a cup of coffee you can buy the paid version.
P.S. If you use this free version, please click on one ad per day to help me out.
----The following is the description for the paid app:
I commute on the WMATA Metro Washington DC subway system five days per week. I tried several apps, but did not like them. So I wrote my own.
The purpose is to display the rail prediction electronic signs you see on the subway station platform. Each sign has three lines and shows when the next three trains will arrive. It will only show trains which will arrive within the next 20 minutes.
1. The capability to see many station's rail predictions at once. The default starting screen shows you every station in the WMATA Metro subway system along with all its rail prediction signs in a scrollable window. You can also select to see only transfer stations or only one rail line – for example the yellow line. When watching one rail line the stations are not in alphabetic order, but instead are in the real station order of that line.
2. The capability to see the rail incidents. This allows you to see where single tracking or disruptions are occurring which may impact your commute.
3. The capability to select the data updating rate. The default rate is 60 seconds and can be lowered as low as 20 seconds. The rail prediction information on WMATA’s web server is updated every 20 seconds.
4. The capability to automatically recover from an internet outage. Sometimes when I enter rail tunnels my Verizon Droid-X loses its 3G internet connection. This application will not bother you with any error messages. There is no need to click on anything to try again. The indicator on the top line of the phone shows there is no 3G internet connection, and the data being displayed by the application shows the time the rail prediction data was retrieved from the WMATA web server. Thus you can see how stale the rail predictions are. When your phone again gets an internet connection, this app will automatically try to get the rail prediction data from the WMATA web server.
5. When this app runs in the background it temporarily stops updating the rail prediction information to conserve data downloading. This means when you press the HOME button updating of the rail predictions will cease until such time that you press this app’s icon to resume its operation.
6. When the phone’s power button is pressed to place it into sleep mode, or the phone’s “Screen timeout” is reached, then this app will cease updating the rail predictions to conserve data downloading.
7. If you tap on the display it will change from black background with white text to become white background with black text. Just tap and see which you prefer.
8. This app is the closest one can get to a real-time display of the entire WMATA rail system.
Note: Sometimes WMATA's server fails and stops providing updated rail predictions to apps asking for MULTIPLE stations' information. You will see old information which never changes. This problem occurs to all apps which allow the user to view many stations at once. This is a problem on WMATA's server which I have no control over. Apps which only allow users to view one single station's rail predictions will often work during this WMATA server failure.