Hanging mics in a Bridge

Time: 1:47 AM
Location: East Juneau Avenue on the bridge over the Milwaukee River

I was walking over the bridge when I noticed I could put my mics through the grates that the cars passed over the bridge on. I put both mics through those grates and let them hang about 2 feet below the bridge. This led to a very low rumble sound which you can hear and almost feel.

Click here to see the location on my drift map.
Click here to listen.