Mackinac Bridge History, Facts and Figures
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Mackinac Bridge Authority
N 415 I-75
St Ignace, MI 49781
(906) 643-7600
Thursday, Apr 23 - 1:35 PM
All Clear, Have a Pleasant Trip!
Full condition report
History
The “Mighty Mac”
Facts & Figures
History of the Bridge
Historical Construction Album
Michigan State Ferry Album
In Memory Of
Thursday, Apr 23 - 1:35 PM
All Clear, Have a Pleasant Trip!
Full condition report
Check out our views of the Bridge
Facts & Figures
The Mackinac Bridge is currently the seventh-longest suspension bridge in the world by total suspended length, and the longest suspension bridge in the western hemisphere.  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”.
LENGTHS
Total Length of Bridge (5 Miles)
26,372 Ft
8,038 Meters
Total Length of Steel Superstructure
19,243 Ft.
5,865 Meters
Length of Suspension Bridge (including Anchorages)
8,614 Ft.
8,614 Ft.
Total Length of North Approach
7,129 Ft.
2,173 Meters
Length of Main Span (between Main Towers)
3,800 Ft.
1,158 Meters
HEIGHTS AND DEPTHS
Height of Main Towers above Water
552 Ft
168.25 Meters
Maximum Depth to Rock at Midspan
Unknown
Unknown
Maximum Depth of Water at Midspan
295 Ft.
90 Meters
Maximum Depth of Tower Piers below Water
210 Ft.
64 Meters
Height of Roadway above Water at Midspan
199 Ft.
61 Meters
Underclearance at Midspan for Ships
155 Ft.
47 Meters
Maximum Depth of Water at Piers
142 Ft.
43 Meters
Maximum Depth of Piers Sunk through Overburden
105 Ft.
32 Meters
CABLES
Total Length of Wire in Main Cables
42,000 Miles
67,592 km
Maximum Tension in Each Cable
16,000 Tons
14,515,995 kg
Number of Wires in Each Cable
12,580
Weight of Cables
11,840 Tons
10,741,067 kg
Diameter of Main Cables
24 1/2 Inches
62.23 cm
Diameter of Each Wire
0.196 Inches
.498 cm
WEIGHTS
Total Weight of Bridge
1,024,500 Tons
929,410,766 kg
Total Weight of Concrete
931,000 Tons
844,588,992 kg
Total Weight of Substructure
919,100 Tons
326,931,237 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 Tons
94,710,087 kg
Total Weight of Structural Steel
71,300 Tons
64,682,272 kg
Weight of Steel in Each Main Tower
6,500 Tons
5,896,701 kg
Total Weight of Cable Wire
11,840 Tons
10,741,067 kg
Total Weight of Concrete Roadway
6,660 Tons
6,041,850 kg
Total Weight of Reinforcing Steel
3,700 Tons
3,356,584 kg
RIVETS AND BOLTS
Total Number of Steel Rivets
4,851,700
Total Number of Steel Bolts
1,016,600
DESIGN AND DETAIL DRAWINGS
Total Number of Engineering Drawings
4,000
Total Number of Blueprints
85,000
MEN EMPLOYED
Total, at the Bridge Site
3,500
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
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