It’s 504 feet long and 80 feet high — the last of the five trussed spans that once formed the central third of the roadway from Oakland’s muddy shore to the forested knob of Yerba Buena Island. [...] even though two decks of asphalt and much of the steelwork has been removed, the homely structure still weighs roughly 3.2 million pounds. If you want a hint of how the latest act of deconstruction will take place, check out the four enormous green metal “wheels” that adorn the corners of the truss. The cables will lift the horizontal truss from its 60-year-old supports, swing it to the side and pivot it out to be lowered onto a pair of barges waiting below. The two barges then take a short voyage to the Port of Oakland, where the trussed section will be transferred to land and dismantled, with the individual beams winding up in recycling facilities across the Bay Area.