Umm, stand down OHSA, they had safety ropes and harnesses. You can clearly see it around 3:44 where they are sweeping the metal off. In a lot of other cases, the crew are behind railings when there is no clear harnesses. Looks pretty careful to me and I would be surprised if there was not an inspector there the entire time.
What I never noticed before was the cool little hopper that the loader hauled off the bridge. In fact, those things that the loaders moved on the tracks with were neat as well.