Editing Mackinac Bridge (section)

===History of the bridge's design===
[[File:Mackinac Bridge-2.jpg|thumb|upright|View of a bridge tower]]
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The design of the Mackinac Bridge was directly influenced by the lessons from the [[Tacoma Narrows Bridge (1940)|first Tacoma Narrows Bridge]], which failed in 1940 because of its instability in high winds. Three years after that disaster, Steinman had published a theoretical analysis of suspension-bridge stability problems, which recommended that future bridge designs include deep stiffening [[truss]]es to support the bridge deck and an open-grid roadway to reduce its wind resistance. Both of these features were incorporated into the design of the Mackinac Bridge. The stiffening truss is open to reduce wind resistance. The road deck is shaped as an airfoil to provide lift in a cross wind, and the center two lanes are open grid to allow vertical (upward) air flow, which fairly precisely cancels the lift, making the roadway stable in design in winds of up to {{convert|150|mph|km/h}}.