NJ thanks for providing the links.
I also thought I would point out that this is a type of hollow concrete box bridge.
It is not 3' or 4' of solid concrete, it is a couple of 10" to 14" decks.
Still amazing but much more believable that slicing a solid concrete bridge.
Zoom in on the first picture where you can see the bucket has punched a hole through the bottom deck in to the void.