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This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (October 2007) |
| Mackinac Bridge | |
|---|---|
 | |
| Carries | 4 lanes of Interstate 75 |
| Crosses | Straits of Mackinac |
| Locale | Mackinaw City and St. Ignace, Michigan |
| Maintained by | Mackinac Bridge AuthorityMackinac Bridge Authority |
| Design | Suspension bridge |
| Longest span | 3,800 feet (1,158 m) |
| Total length | 26,372 feet (8,038 m) |
| Width | 68 feet (20.7 m) |
| Height | 522 feet (159 m) |
| Vertical clearance | 200 feet (61 m) |
| Clearance below | 155 feet (47 m) |
| AADT | 11,600 |
| Opening date | November 1, 1957 |
| Toll | $1.50 per axle for passenger vehicles ($3.00 per car). $3.50 per axle for motor homes. $3.50 per axle for commercial vehicles.Mackinac Bridge Authority. Mackinac Bridge Authority reminds motorists tolls go up March 1. Retrieved on 2008-03-06. |
| Connects: Mackinaw City and St. Ignace | 
|
| Maps and aerial photos | |
The Mackinac Bridge (pronounced /ˈmækɨnɔː/, with a silent "c" at the end of the word), is a suspension bridge spanning the Straits of Mackinac to connect the non-contiguous Upper and Lower peninsulas of the U.S. state of Michigan. Envisioned since the 1880s, the bridge was completed only after many decades of struggles to begin construction. Designed by engineer David B. Steinman, the bridge (familiarly known as "Big Mac" and "Mighty Mac") connects the city of St. Ignace on the north end with the village of Mackinaw City on the south.
Contents |
The bridge opened on November 1, 1957, ending 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". This designation was chosen because the bridge would not be the world\'s largest using another way of measuring suspension bridges, the length of the center span between the towers; at the time that title belonged to the Golden Gate Bridge, which has a longer center span. By saying "between anchorages", the bridge could be considered longer than the Golden Gate Bridge, and also longer than the suspended western section of the San Francisco-Oakland Bay Bridge. (That bridge has a longer total suspension but is a double bridge with an anchorage in the middle.)
The Mackinac Bridge is the longest suspension bridge with two towers between anchorages (8,614 feet) (2,626 m) in the Western Hemisphere. Much longer anchorage-to-anchorage spans have been built in the Eastern Hemisphere, including the Akashi-Kaikyo Bridge in Japan (12,826 feet) (3,909 m). However, because of the long leadups to the anchorages on the Mackinac, from shoreline to shoreline it is much longer than the Akashi-Kaikyo (5 miles compared to 2.4 miles).
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.
Before the construction of the bridge, the typical way to cross the Straits of Mackinac was by ferry. A fleet of nine ferries could carry up to 9,000 vehicles per day. Traffic backups sometimes stretched to Cheboygan, Michigan, 16 miles (26 kilometers) away from Mackinaw City. Year-round boat service across the straits had been abandoned as impractical because of the cold winters which would often freeze the water across the entire strait. Following the opening of the Brooklyn Bridge in 1883, local residents began to imagine such a structure could span the straits. In 1884, a store owner in St. Ignace published a newspaper advertisement that included a reprint of an artist\'s conception of the Brooklyn Bridge with the caption "Proposed bridge across the Straits of Mackinac."
A Mackinac Island ferry passing in front of the Mackinac Bridge.
The idea of the bridge was discussed in the Michigan Legislature as early as the 1880s. At the time the area was becoming a popular tourist destination, including the creation of Mackinac National Park on Mackinac Island in 1875.
Despite the perceived necessity for the bridge, several decades elapsed with no formal plan. In 1920, the Michigan state highway commissioner advocated the construction of a floating tunnel across the straits. At the invitation of the state legislature, C. E. Fowler of New York City put forth a plan for a long series of causeways and bridges across the straits from Cheboygan, 17 miles (27 km) southeast of Mackinaw City, to St. Ignace, using Bois Blanc, Round, and Mackinac Island as intermediate steps.
In 1923, the state legislature ordered the State Highway Department to re-establish ferry service across the strait. By 1928, however, the service had become so expensive to operate that Michigan Governor Fred Green ordered the department to study the feasiblity of building a bridge across the strait. The department deemed the idea feasible, estimating the cost at 30 million dollars.
In 1934, the Michigan Legislature created the Mackinac Straits Bridge Authority of Michigan, to study the feasiblity of the bridge, and authorized the Authority to sell bonds for the project. In the mid 1930s, the Authority twice attempted to obtain federal funds for the project but was unsuccessful, despite the endorsement of the United States Army Corps of Engineers and President Franklin D. Roosevelt. Nevertheless, between 1936 and 1940, a route was selected for the bridge and borings were made for a detailed geological study of the route.
The preliminary plans for the bridge featured a 3-lane roadway, a railroad crossing on the underdeck of the span, and a center-anchorage double-suspension bridge configuration similar to the design of the San Francisco-Oakland Bay Bridge. Since this would have required sinking an anchorage pier in the deepest area of the Straits, the practicality of this design may have been questionable. A causeway, approximately 4,000 feet (1,219 m), extending from the northern shore, was constructed with concrete road fragments from 1939-1941.
At that time, with funding for the project still uncertain, further work was put on hold because of World War II. The Authority was abolished by the state legislature in 1947 but was reauthorized three years later in 1950. In June 1950, engineers were retained for the project. Following a report by the engineers in January 1951, the state legistature authorized the sale of 85 million dollars in bonds for bridge construction on April 30, 1952. However, a weak bond market in 1953 forced a delay of over a year before the bonds could be issued.
G. Mennen Williams was governor during the construction of the Mackinac Bridge. He began the tradition of the governor leading the Mackinac Bridge Walk across it every Labor Day.Governor G. Mennen Williams
View of the bridge looking north across the Straits of Mackinac
David B. Steinman was appointed as the design engineer in January 1953. By the end of 1953, estimates and contracts had been negotiated, and construction began on May 7, 1954. The American Bridge Division of United States Steel Corporation was awarded a contract of over 44 million dollars to build the steel superstructure. Construction took three and a half years (4 summers, no winter construction) and cost the lives of five men who worked on the bridge. It opened to traffic on schedule on November 1, 1957, and was formally dedicated on June 25, 1958. The bridge officially achieved its 100 millionth crossing exactly forty years after its dedication, on June 25, 1998. The 50th anniversary of the bridge\'s opening was celebrated in a ceremony hosted by the Mackinac Bridge Authority at the viewing park adjacent to the St. Ignace causeway on November 1, 2007.
The design of the Mackinac Bridge was directly influenced by the 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 trusses to support the bridge deck and an open-grid roadway to reduce its wind resistance. Both of these features were incorporated into 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, while 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 up to 150 m.p.h.
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Mackinac Bridge at night
Mackinac Bridge during a snowstorm(Picture taken from a road that leads up to the Bridge View Park).
Five workers died during the construction of the bridge.
All five men are memorialized on a plaque near the bridge\'s southern end. Contrary to folklore, no bodies are embedded in the concrete.Michigan History Magazine July/August 2007Frequently Asked Questions. Mackinac Bridge Authority (2008). Retrieved on 2008-02-15.
One worker has died since the bridge was completed.
Two vehicles have fallen off the bridge.
The Mackinac Bridge Authority has a "Drivers Assistance Program" that provides drivers for those uncomfortable with driving across the Mackinac Bridge. Those interested can arrange, either by phone or with the toll collector, to have their cars driven to the other end. There is no additional fee for this service.
Travelers across the Mackinac Bridge can listen to a special radio broadcast which recounts the history of the bridge and provides updates on driving conditions
Wikimedia Commons has media related to:
| History of Michigan | |
|---|---|
| Timeline |
Glaciation · Paleo-Indian · Archaic · Woodland · Algonquian · French · British · Territory · State |
| Native |
Ojibwa · Potawatomi · Menominee · Fox · Sac · Ottawa · Mascouten · Kickapoo · Miami |
| Colonial |
Fur Trade · Coureurs des Bois · Iroquois Wars · New France · Detroit · Fox Wars · Fort Michilimackinac · Seven Years\' War · Peace of Paris · Pontiac\'s Rebellion · Royal Proclamation · Indian Reserve · Quebec Act · Revolutionary War · Treaty of Paris |
| United States |
Northwest Territory · Jay Treaty · Treaty of Saginaw · Treaty of Chicago · Chicago Road · Toledo War · Clinton-Kalamazoo Canal · Patriot War · Treaty of La Pointe · Civil War · Auto Makers · River Rouge Plant · Ambassador Bridge · Detroit–Windsor Tunnel · Flint Sit-Down Strike · Mackinac Bridge · 12th St. Riot · Gerald Ford |
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