> A reporter asked how the new bridge would be secured to the old substructure. "It’s 400 tons," said Walter Heller ... "Nobody’s going to pick it up and take it home."

I don't think the reporter meant "secured" in the sense of preventing theft. Is a 400-ton bridge heavy enough not to rattle and damage the surrounding concrete if 18-wheelers repeatedly cross it at high speed? Or flip over if a train hits it from below?