One of many trusses supporting the bridge for 80 years.
About 85 years ago an engineer relying on a slide rule, pencil and good education, determined the design loads that this truss would have to carry, assigned a safety factor, and calculated the dimensions of all the components that make it up. Plans were drawn with pencil and drafting tools for constructing the multitude of individual bridge parts. The plan set documented every detail like rounded edges, length, width, thickness, rivet holes and assembly. The process was repeated for each unique piece of the bridge. The plans were passed on to a mill where the steel was rolled, cut, stamped, milled and drilled into the various components. Thousands of prefabricated parts were then transported to a site in the wilderness where another crew of workers assembled this truss and all the others into a bridge that has stood for 80 years and now carries 20,000 cars and 2,000 heavy trucks per day.