Last month marked the anniversary of the Mackinac Bridge, which opened to traffic on Nov. 1, 1957. “The Mighty Mac,” a suspension bridge spanning the Straits of Mackinac between Lake Michigan and Lake Huron, connects the lower and upper peninsulas of Michigan.
Prior to the construction of the bridge, a fleet of nine ferries would carry as many as 9,000 vehicles per day, with traffic backups stretching as far as 16 miles. The design of the Mackinac Bridge was directly influenced by the lessons of the first Tacoma Narrows Bridge, which failed Nov. 7, 1940, due to instability in high winds.
Three years after the Tacoma Narrows disaster, engineer David Steinman published a theoretical analysis of suspension bridge stability problems, which recommended that future bridge designs include deep stiffening trusses to support the bridge deck and an open grid roadway to reduce wind resistance. In January 1953, Steinman was appointed as the design engineer for the Mackinac Bridge, where his recommendations were incorporated.
The bridge opened according to schedule, Nov.1, 1957, despite the many hazards of marine construction in harsh weather over the turbulent Straits of Mackinac. The opening ended decades of the two peninsulas being solely linked by ferries. A year later, the bridge was formally dedicated as the world’s longest suspension bridge between anchorages.
By stating “between anchorages,” the bridge could be considered longer than the Golden Gate Bridge. At 8,614 feet (2,626 m), the Mackinac Bridge is still the longest suspension bridge between anchorages in the Western Hemisphere. The length of the bridge’s main span is 3,800 feet (1,158 m), which makes it the third-longest suspension span in the United States and twelfth longest worldwide.
In his later life, Steinman took interest in poetry and his enthusiasm for bridge building was reflected in his writing. Among Steinman’s poems was his ode to the Mighty Mac:
The Bridge at Mackinac
In the land of Hiawatha
Where the white man gazed with awe
At a paradise divided
By the straits of Mackinac
Men are dredging, drilling, blasting
Battling tides around the clock
Through the depths of icy water
Driving caissons down to rock
Fleets of freighters bring their cargoes
From the forges and the kilns
Stones and steel – ten thousand barge-loads
From the quarries, mines, and mills
Now the towers, mounting skyward
Reach the heights of airy space
Hear the rivet-hammers ringing
Joining steel in strength and grace
High above the swirling currents
Parabolic strands are strung
From the cables, packed with power
Wonder-spans of steel are hung
Generations dreamed the crossing
Doubters shook their heads in scorn
Brave men vowed that they would build it
From their faith a bridge was born
There it spans the miles of water
Speeding millions on their way
Bridge of vision, hope and courage
Portal to a brighter day
The Mackinac Bridge was recognized by ASCE as a National Historic Civil Engineering Landmark in 2009.