More than just oddly engaging, the time-lapse video above of one of the new 520 bridge pontoons just barely fitting through the Ballard locks is also a reminder of the engineering constraints on the project. Anything wider would've had to have been constructed on Lake Washington.

And if you're hankering for more video of giant floating slabs of concrete, after the jump we have five pontoons being floated from their casting facility in Aberdeen, WA: