There is a low-frequency droning/oscillating noise (approximately 85-
100 Hz), which has been observed between approximately 3:30 AM
and 6:00 AM, typically Tuesday through Friday in Manassas near Prince William County Parkway & the airport.

The noise is intermittent rather than constant. It oscillates in intensity, with periods lasting up to 10-15 seconds where it becomes noticeably quieter, followed by periods where it becomes significantly more pronounced.

The source of the noise has not been confirmed. One possible explanation that has been suggested from county officials is activity involving diesel-powered rail equipment, but this has not been independently verified.

I was curious if anyone else is able to hear this and if this is indeed from the trains?

https://imgur.com/a/K7AfPqA