The bats came out in an incredible stream, I stayed for about a half hour until it became too dark to see. I was about 50 feet from the side of the old train tunnel, the bats came out at one point at about 1000 per second. They flew to the treeline, spiraled upwards, and then flew off. From where I was it looked like a bat tornado. The sound of the wings was incredible, as was the overpowering smell of ammonia! Many bats broke from the main group and flew around our viewing area nearly close enough to touch. We could hear many bat vocalizations as well.
Sorry for the video quality, it was getting quite dark. I see several other videos on YouTube of the same thing, search for Old Tunnel or Bat Emergence if you would like to see more of what I saw.
