Wonder if the NG has the tunnels under DC manned?
LIVE DC Metro Train Map
https://gis.wmata.com/metrotrain/index.html
Just heard this on 8992kHz
http://websdr.ewi.utwente.nl:8901/
Having trouble converting a .wav audio file to something that will upload here. action going on 8992kHz today
Sounds similar to a old dial up modem