WSDOT has posted some really good timelapse videos of 520 construction.
The first here shows installing girders in Medina last weekend:
More below the fold (including some non-WSDOT videos I like).
Here is Bellevue Way semi-destructino from a few weeks ago:
Here’s a time lapse of Muni Rails being replaced in San Francisco:
Here’s a time lapse in slow motion, taken by a high-speed camera from a train.