Facts & Figures

Facts & Figures

The Mackinac Bridge is currently the fifth longest suspension bridge in the world.  The bridge opened to traffic on November 1, 1957.  The following facts and figures are quoted from David Steinman's book "Miracle Bridge at Mackinac".
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LENGTHS

Total Length of Bridge (5 Miles) 26,372 Ft.
8,038 Meters
Total Length of Steel Superstructure19,243 Ft.
5,865 Meters
Length of Suspension Bridge (including Anchorages)8,614 Ft.
2,626 Meters
Total Length of North Approach 7,129 Ft. 2,173 Meters
Length of Main Span (between Main Towers) 3,800 Ft.
1,158 Meters


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HEIGHTS AND DEPTHS

Height of Main Towers above Water
552 Ft168.25 Meters
Maximum Depth to Rock at MidspanUnknownUnknown
Maximum Depth of Water at Midspan295 Ft.90 Meters
Maximum Depth of Tower Piers below Water210 Ft.64 Meters
Height of Roadway above Water at Midspan199 Ft.61 Meters
Underclearance at Midspan for Ships 155 Ft.47 Meters
Maximum Depth of Water at Piers142 Ft.43 Meters
Maximum Depth of Piers Sunk through Overburden105 Ft.32 Meters


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CABLES

Total Length of Wire in Main Cables42,000 Miles
67,592 km
Maximum Tension in Each Cable16,000 Tons
14,515,995 kg
Number of Wires in Each Cable12,580
Weight of Cables11,840 Tons10,741,067 kg
Diameter of Main Cables24 1/2 Inches62.23 cm
Diameter of Each Wire 0.196 Inches .498 cm






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WEIGHTS

Total Weight of Bridge 1,024,500 Tons 929,410,766 kg
Total Weight of Concrete931,000 Tons844,589 kg
Total Weight of Substructure 919,100 Tons833,793,495 kg
Total Weight of Two Anchorages 360,380 Tons 326,931,237 kg
Total Weight of Two Main Piers 318,000 Tons 288,484,747 kg
Total Weight of Superstructure 104,400 Tons94,710,087 kg
Total Weight of Structural Steel 71,300 Tons 64,682,272 kg
Weight of Steel in Each Main Tower 6,500 Tons5,896,701 kg
Total Weight of Cable Wire 11,840 Tons 10,741,067 kg
Total Weight of Concrete Roadway 6,660 Tons6,041,850 kg
Total Weight of Reinforcing Steel
3,700 Tons3,356,584 kg


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RIVETS AND BOLTS

Total Number of Steel Rivets 4,851,700
Total Number of Steel Bolts 1,016,600



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DESIGN AND DETAIL DRAWINGS

Total Number of Engineering Drawings4,000
Total Number of Blueprints 85,000

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MEN EMPLOYED

Total, at the Bridge Site3,500
At Quarries, Shops, Mills, etc. 7,500
Total Number of Engineers 350





IMPORTANT DATES

Mackinac Bridge Authority Appointed  June, 1950
Board of Three Engineers Retained  June, 1950
Report of Board of Engineers January, 1951
Financing and Construction Authorized by Legislature April 30, 1952
D.B. Steinman Selected as Engineer January, 1953
Preliminary Plans and Estimates Completed
March, 1953
Construction Contracts Negotiated March, 1953
Bids Received for Sale of Bonds December 17, 1953
Began Construction May 7, 1954
Open to traffic November 1, 1957
Formal dedication June 25-28, 1958
50 millionth crossing September 25, 1984
40th Anniversary Celebration
November 1, 1997
100 millionth crossing June 25, 1998