Monday, May 27, 2013

Mackinac Bridge

Chronology:
February 5, 1884 - The Lansing Republican newspaper dated and reprinted a story from a former newspaper, the Grand Traverse Herald that pointed out the experiment to provide all-year service across the Straits by boat had failed, and if a great east-west route were ever to be established through Michigan a bridge or tunnel would be required. Both a tunnel or bridge was considered practicable by the editor but the only question in his mind was that of cost.

1883 - The Brooklyn Bridge is dedicated. This gave Mackinac Bridge backers encouragement.

1884 - A St. Ignace store owner reprinted an artist's conception of the famous New York structure in his advertising and captioned it "Proposed bridge across the Straits of Mackinac."

July 1, 1888 - The board of directors of the famous Grand Hotel at Mackinac Island held their first meeting and the minutes show that Cornelius Vanderbilt said: "We now have the largest, well-equipped hotel of its kind in the world for a short season business. Now what we need is a bridge across the Straits."

1889 - The great Firth of Forth Bridge in Scotland was completed.

1889 to 1920 - During the ensuing years there were a few farfetched ideas about the connection of Michigan's two peninsulas.

1920 - The state highway commissioner suggested a floating tunnel. He invited other engineers to suggest ideas for crossing the Straits. Mr. C. E. Fowler of New York City came forward with an ambitious project to solve the problem with a series of bridges and causeways that would start at Cheboygan, some 17 miles southeast of Mackinaw City, traverse Bois Blanc and Round Islands, touch the southern tip of Mackinac Island, and leap across the deep channel at St. Ignace.

1923 - The Michigan State Legislature ordered the State Highway Department to establish a ferry service at the Straits. Within five years traffic on this facility became so heavy that the late Governor Fred Green ordered the same agency to make a study of bridge feasibility. The report was favorable and its cost was estimated at 30 million dollars. Some strides to get the project underway were taken but it was eventually dropped.

1934 - The matter of the bridge was again revived and proposed as a suitable P.W.A. project. In the extra session of that same year the Legislature created the Mackinac Straits Bridge Authority of Michigan and empowered it to investigate the feasibility of such construction and to finance the work by issuance of revenue bonds.

May 1934 - The Authority began its studies and has been continuously active since that date.

1934 to 1936 - Although limited funds precluded full and complete preliminary studies, the Authority was able to reach the conclusion that it was feasible to construct a bridge directly across the Straits at an estimated cost of not more than $32,400,000 for a combined two lane highway and one-track railway bridge. In its studies the Authority utilized soundings made by the War Department Engineers and was aided by the gratuitous counsel and advice of engineers and contractors experienced in work of this magnitude."

The Authority made two attempts to obtain loans and grants from the Federal Emergency Administration of Public Works, but P.W.A. refused both applications despite endorsement by the U.S. Army Corps of Engineers and the report that the late President Roosevelt favored the bridge.

1936 to 1940 - Notwithstanding setbacks, bridge backers resumed their efforts with their usual vigor. A new direct route was selected, borings were made, traffic, geologic, ice and water current studies of a very comprehensive nature were completed. A mole or causeway jutting 4,200 feet into the Straits from St. Ignace south was constructed. Preliminary plans for a double suspension span were drawn and the possibility of a bridge became very real. But the Armies of Europe began to march and bridge progress came to a halt.

1947 - The State Legislature abolished the Mackinac Straits Bridge Authority.

1947 to 1950 - Again, the bridge backers swung into action and a citizens' committee was established to obtain legislation recreating a bridge authority.

1950 - The legislation was enacted, but it limited the newly created Authority to determine feasibility only. The law required the Authority to consult with three of the world's foremost long span bridge engineers and traffic consultants for advice on physical and financial feasibility.

June, 1950 - Mackinac Bridge Authority appointed and board of three engineers retained

January, 1951 - The Authority submitted a very favorable preliminary report, stating that a bridge could be built and financed with revenue bonds for $86,000,000 but because of the shortage of materials due to the Korean outbreak, legislation to finance and build the structure was delayed until early in 1952. Immediately, the Authority asked the Reconstruction Finance Corporation to purchase $85,000,000 worth of bonds.

April 30, 1952 - Financing and construction authorized by Legislature.

January, 1953 - D.B. Steinman selected as engineer.

March, 1953 - The Authority accepted the offer and was ready to offer its bonds for sale. There were not enough takers to guarantee successful underwriting. The money market had weakened. The preliminary plans and estimates were completed and construction contracts were negotiated.

Spring 1953 - In order to make the bonds more attractive, the Legislature passed an act during the whereby the operating and maintenance cost of the structure, up to $417,000 annually, would be paid for out of gasoline and license plate taxes.

June 1953 - Another effort to finance with this added inducement was likewise unsuccessful, but toward the end of the year the market recovered and $99,800,000 worth of Mackinac Bridge bonds were bought by investors all over the country. Contracts which had been awarded contingent upon this financing were immediately implemented.

December 17, 1953 -
Bids received for sale of bonds.

May 7 & 8, 1954 - The five-mile bridge, including approaches, and the world's longest suspension bridge between cable anchorages, had been designed by the great engineer Dr. David B. Steinman. Merritt-Chapman & Scott Corporation's $25,735,600 agreement to build all the foundations led to the mobilization of the largest bridge construction fleet ever assembled. The American Bridge Division of United States Steel Corporation, awarded a $44,532,900 contract to build this superstructure, began its work of planning and assembly. In U.S. Steel's mills the various shapes, plates, bars, wire and cables of steel necessary for the superstructure and for the caissons and cofferdams of the foundation, were prepared. The bridge was officially begun amid proper ceremonies at St. Ignace and Mackinaw City.

November 1, 1957 - The bridge opened to traffic according to schedule, despite the many hazards of marine construction over the turbulent Straits of Mackinac.

June 25 to 28, 1958 -
Formal dedication.

September 25, 1984 -
50 millionth crossing.

July 1, 1986 - The last of the Mackinac Bridge bonds were retired. Fare revenues are now used to operate and maintain the Bridge and repay the State of Michigan for monies advanced to the Authority since the facility opened to traffic in 1957.

November 1, 1997 - 40th Anniversary Celebration.

June 25, 1998 - 100 millionth crossing.

November 1, 2007 - 50th Anniversary Celebration.

Bridge Facts:

The Mackinaw Bridge is currently the third longest suspension bridge in the world.

LENGTHS
Total Length of Bridge: (5 Miles) 26,372 Ft. or 8,038 Meters
Total Length of Steel Superstructure: 19,243 Ft. or 5,865 Meters
Length of Suspension Bridge (including Anchorages): 8,614 Ft. or 2,626 Meters
Total Length of North Approach: 7,129 Ft. or 2,173 Meters
Length of Main Span (between Main Towers): 3,800 Ft. or 1,158 Meters

HEIGHTS AND DEPTHS
Height of Main Towers above Water: 552 Ft. or 168.25 Meters
Maximum Depth to Rock at Midspan: Unknown
Maximum Depth of Water at Midspan: 295 Ft. or 90 Meters
Maximum Depth of Tower Piers below Water: 210 Ft. or 64 Meters
Height of Roadway above Water at Midspan: 199 Ft. or 61 Meters
Underclearance at Midspan for Ships: 155 Ft. or 47 Meters
Maximum Depth of Water at Piers: 142 Ft. or 43 Meters
Maximum Depth of Piers Sunk through Overburden: 105 Ft. or 32 Meters

CABLES

Total Length of Wire in Main Cables: 42,000 Miles or 67,592 km
Maximum Tension in Each Cable: 16,000 Tons or 14,515,995 kg
Number of Wires in Each Cable: 12,580
Weight of Cables: 11,840 Tons or 10,741,067 kg
Diameter of Main Cables: 24 1/2 Inches or 62.23 cm
Diameter of Each Wire: 0.196 Inches or 0.498 cm

WEIGHTS
Total Weight of Bridge: 1,024,500 Tons or 929,410,766 kg
Total Weight of Concrete: 931,000 Tons or 844,589 kg
Total Weight of Substructure: 919,100 Tons or 833,793,495 kg
Total Weight of Two Anchorages: 360,380 Tons or 326,931,237 kg
Total Weight of Two Main Piers: 318,000 Tons or 288,484,747 kg
Total Weight of Superstructure: 104,400 Tons or 94,710,087 kg
Total Weight of Structural Steel: 71,300 Tons or 64,682,272 kg
Weight of Steel in Each Main Tower: 6,500 Tons or 5,896,701 kg
Total Weight of Cable Wire: 11,840 Tons or 10,741,067 kg
Total Weight of Concrete Roadway: 6,660 Tons or 6,041,850 kg
Total Weight of Reinforcing Steel: 3,700 Tons or 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

Photos:

Bridge view from staging area for Mighty Mac Bridge Bike Ride and while riding bike across the bridge:
































































Bridge view from Arnold Line Ferry on Lake Huron between St. Ignace and Mackinaw City:






































































































Bridge view from top of Old Makcinac Point Lighthouse:

























Bridge view from along shore of Lake Huron:


































Under side of bridge on Mackinaw City side:









Bridge view from along shore of Lake Michigan:









View of bridge at night:

























































View from Mackinac Island:
































Website: Mackinac Bridge

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