[steve in DC]

About half way between those two people you will see the walkway go up and over a speedbump.

That speedbump was not in the original design!

That's the buckling.

[AFreeBird]

Also, if you load the high res version (pic 1); if you look back towards the middle (maybe a little aft of the middle) of the sail just under the walkway, you'll see what appears to be a slight bulge there too.