NYC bridge flexing as subway passes [VIDEO]

[Neo]

Obviously bridges flex, but I had no idea it was this much. Below is a video of a bridge in New York City flexing as a subway passes (multiple times):

[Titoroski]

oh wow!

[Mith242]

Guess that's why they don't call it light rail.

[jarvismj]

Aren't bridges like that supposed to have little play in them? I know that you don't want them to be completely ridgid.

[Neo]

Aren't bridges like that supposed to have little play in them? I know that you don't want them to be completely ridgid.

Of course, but it's interesting to see just how much they do flex.

[lime light power]

Of course, but it's interesting to see just how much they do flex.

I went to U Penn architecture a long time ago and I remember walking on the bridges over the Schuylkill River from the downtown side to the Penn side and, obviously being an architecture student, remember watching the expansion joints in the bridge throughout the course of the year. Especially noticeable during the early winter as temperatures swung widely from midday to evening... the difference between the two could actually be many inches... from my memory the expansion "fingers" were easily 6 maybe even 8 inches... like everything bridges need to breath. One of my professors said, "When the bridge stops moving, that's when it's time to worry."... good video, nice to see it in action.