Mackinac Bridge ( "English respelling pronunciation"> MAK -in-aw ) is a hanging bridge that stretches Strait of Mackinac to connect Upper and Lower Peninsulas of the US state of Michigan. Opened in 1957, a 26,372-foot (4,995 mi; 8,038 km) bridge (known as the "Big Mac " and " Mighty Mac ") is the world's 20th longest span and the longest suspension bridge between anchorages in the western hemisphere. The Mackinac Bridge is part of Interstate 75 and Lake Michigan and the Huron component of the Great Lakes Circle Tours across the straits; this is also a segment of the National National Scenic Trail National US State. The bridge connects St. Ignace on the north end with the village of Mackinaw City in the south.
Imagined since the 1880s, the bridge was designed by engineer David B. Steinman and completed in 1957 just after decades of struggle to begin construction.
Video Mackinac Bridge
Length
The bridge opened on November 1, 1957, connecting two peninsula that were connected for decades by ferry. A year later, the bridge was officially dedicated as "the longest suspension bridge in the world between anchors", enabling superlative comparisons with the Golden Gate Bridge, which has a longer middle range between towers, and San Francisco-Oakland Bay Bridge, which has an anchorage in the middle.
It remains the longest suspension bridge with two towers between the anchors in the western hemisphere. A longer anchorage-to-anchorage range has been built in the eastern hemisphere, including Akashi Kaiky? Bridge in Japan (6,532 feet or 1,991 m). But the length of the ascent to Mackinac makes the coastline along the coastline to 5 miles (8 km) longer than Akashi-Kaikyo (2.4 miles or 3.9 km).
The bridge's main span length is 3,800 feet (1,158 m), making it the third longest suspension range in the United States and the 20th longest suspension range worldwide. It is also one of the longest bridges in the world as a whole.
Maps Mackinac Bridge
History
Initial history
The Algonquian people who lived in the strait area prior to the arrival of Europeans in the 17th century called this region the Michilimackinac , which is widely understood as the Great Turtle. This is thinking of referring to what is now called Mackinac Island. The interpretation of this word is disputed by the experts. Trading posts in the Strait of Mackinac attract peak populations during the summer trading season; they are also developed as inter-meeting places.
When the exploitation of state mineral and wood resources increased during the 19th century, the area became an important transportation hub. In 1881 three railway lines reached the Straits, Central Michigan, Grand Rapids & Indiana, and Detroit, Mackinac & amp; Marquette, jointly founded the Mackinac Transport Company to operate the railroad car ferry service across the strait and connect the two peninsula.
The increase of the highway along the eastern coast of the Lower Peninsula brought increased car traffic to the Straits region beginning in the 1910s. The state of Michigan started a car ferry service between Mackinaw City and St. Louis. Ignace in 1923; eventually operating nine ferries that will carry as many as 9,000 vehicles per day. Backup traffic can stretch as far as 16 miles (26 km).
Package for bridge
After the opening of the Brooklyn Bridge in 1883, local residents began to imagine that such structures could reach the straits. In 1884, the shopkeeper in St. Ignace published a newspaper ad containing a reprint of an artist's conception of the Brooklyn Bridge under the title "The proposed bridge across the Strait of Mackinac".
The idea of ​​the bridge was discussed in the Michigan Legislature as early as the 1880s. At that time, the Straits of Mackinac area became a popular tourist destination, especially after the creation of Mackinac National Park in Mackinac Island in 1875.
At a meeting of 18 July 1888 the board of directors of Grand Hotel on Mackinac Island, Cornelius Vanderbilt II proposed that the bridge was built on the strait, from a design similar to that later built across the Firth of Forth in Scotland. This will promote trade in the region and help extend the resort season of the hotel.
Decades passed without formal action. In 1920, Michigan state highway commissioners advocated the construction of a floating tunnel across the Strait. At the invitation of the state legislature CE Fowler of New York City submitted a plan for a long series of bridges and bridges across the Cheboygan Channel, 17 miles (27 km) southeast of Mackinaw City, to St. Ignace, using Bois Blanc, Spherical, and Mackinac Islands as a follow-up step.
Formal planning
In 1923, the state legislature ordered the State Highway Department to build a ferry service across the strait. More and more people use ferries to cross the straits every year, and as they do, the movement to build bridges increases. Chase Osborn, a former governor, writes,
"Michigan brings together, and a stunning new route through Michigan to Lake Superior and the Northwest United States is expanding, through the Straits of Mackinac.It can not continue to grow as it should with a clunky and inadequate ferry for every part of the year."
By 1928, ferry services had become so popular and so expensive to operate that Michigan Governor Fred W. Green ordered the department to study the feasibility of building bridges across the straits. The Department considers the idea feasible, estimating a $ 30 million (equivalent to $ 338 million in 2016).
In 1934, the Michigan Legislature created the Mackinac Straits Bridge Authority to explore possible methods of building and funding the proposed bridges. The Legislature authorizes the Authority to seek funding for the project. In the mid-1930s, during the Great Depression, when many infrastructure projects received federal assistance, the Authority twice attempted to obtain federal funds for the project but to no avail. The United States Army Engineer Corps and President Franklin D. Roosevelt supported the project but Congress never allocated funds. Between 1936 and 1940, the Authority selected a route for the bridge based on a preliminary study. Borings made for detailed geological studies of the route.
The initial plan for this bridge featured a 3-lane road, a railway crossing under a narrow span, and an anchor center-center suspension configuration similar to the San Francisco-Oakland Bay Bridge design. Since this would require drowning the harbor docks in the deepest areas of the Strait, the practicality of this design might be questioned. A concrete cross road, about 4,000 feet (1,219 m), stretches from the north coast, built in shallow water from 1939 to 1941. However, the unique engineering challenge was created by the overwhelming power operating against the base of the bridge, since the lake froze during the seasons cold, causing a huge iceberg to put great pressure on the bridge.
At that time, with funding for the project still uncertain, further work was postponed due to the outbreak of World War II. The Mackinac Straits Bridge Authority was removed by the state legislature in 1947, but the same agency created the new Mackinac Bridge Authority three years later in 1950. In June 1950, the engineers were retained for the project the. At that time, it was reported that cars queuing for ferries in Mackinaw City did not reach St. Ignace up to five hours later, and the typical capacity of 460 vehicles per hour can not match the 1600 forecast for a bridge.
After a report by engineers in January 1951, the state legislature authorized the sale of $ 85 million (equivalent to $ 633 million in 2016) in bonds for the construction of the bridge on April 30, 1952. However, a weak bond market in 1953 forced a further delay of one year before the bond can be issued.
Engineering and construction
David B. Steinman was appointed as design engineer in January 1953 and by the end of 1953, estimates and contracts had been negotiated. A Civil Engineer at the firm, Abul Hasnat, made an initial plan for the bridge. The estimated total cost at the time was $ 95 million (equivalent to $ 698 million in 2016) with an estimated settlement on November 1, 1956. The toll collected was to pay the bridge within 20 years. Construction began on May 7, 1954. The United States Steel Corporation's bridge division was awarded a contract of more than $ 44 million (equivalent to $ 320 million in 2016) to build a steel superstructure.
The construction, staged using the 1939-41 crossroads, takes three and a half years (four summers, no winter construction) for a total cost of $ 100 million and the lives of five workers. Contrary to popular belief, none of them are buried at the Bridge. It opened to traffic as scheduled on November 1, 1957, and the ferry service was discontinued on the same day. The Bridge was officially dedicated on June 25, 1958.
G. Mennen Williams was governor during the construction of the Mackinac Bridge. He started the tradition of governor who led the Mackinac Bridge Walk on every Labor Day. US Senator Prentiss M. Brown has been called "the father of the Mackinac Bridge," and was honored with a special memorial warning sign made by the Mackinac Bridge Authority.
The bridge officially reached its 100 million crossing just forty years after its dedication, on June 25, 1998. The 50th anniversary of the opening of the bridge was celebrated on November 1, 2007 in a ceremony hosted by the Mackinac Bridge Authority in a park view adjacent to the road St. Ignace.
The history of bridge design
The Mackinac Bridge design is directly influenced by the lessons learned from the first Tacoma Narrows Bridge, which failed in 1940 due to its instability in strong winds. Three years after the disaster, Steinman has published the theoretical analysis of suspension-bridge stability issues, which recommend that future bridge designs include deep truss to support the bridge deck and open grid roads to reduce wind resistance. Both of these features are incorporated into the Mackinac Bridge design. Rigid frames are open to reduce wind resistance. The road deck is formed as an airfoil to provide lift in high winds, and the two-lane center is an open grid to allow for vertical airflow (upwards), which simply lifts the elevator, making the road stable in wind design up to 150 miles per hour ( 240 km/h).
Facts and numbers
The Mackinac Bridge is currently a toll bridge on Interstate 75 (I-75). Prior to the I-75 arrival, the bridge carried US Highway 27 (US $ 27). It is one of only three I-75 segments tolling; the other is half America from the International Bridge near Sault Ste. Marie, Michigan, and Alligator Alley in Florida. The current toll amount is $ 4.00 for the car and $ 5.00 per axle for the truck. The Mackinac Bridge Authority raised tolls in 2007 to fund a $ 300 million renovation program, which will completely replace the bridge deck.
Every Labor Day, the bridge is open for pedestrians to Mackinac Bridge Walk.
The painting of the bridge takes seven years, and when the painting of the bridge is over, it begins again. The painting project is currently starting in 1999 and is expected to take 20 years to complete because lead paint needs to be removed, resulting in additional disposal requirements.
The bridge celebrates 150 million vehicles that flew on 6 September 2009.
- The length of the crooked cable to the crooked cable dock: 7,400 feet (2,256 m).
- The total width of the road: 54 feet (16.5 m)
- Two outer lanes: 12 feet (3.7 m) wide each
- Two inner lanes: 11 feet (3.4 m) wide each
- Shopping center: 2 feet (0.61 m)
- Wide catwalk, sidewalk and rail: 3 feet (0.91 m) on each side
- Rigid frame width in suspended range: 68 feet (20.7 m).
- The depth of a rigid truss: 38.1 feet (11.6 m)
- Highway height in mid range: approximately 200 feet (61 m) above water level.
- Vertical distance at normal temperature:
- 155 feet (47 m) in the center of the main suspension range.
- 135 feet (41 m) at 3,000 feet (914 m) navigation channel limit.
- Construction cost: $ 99.8 million (equivalent to $ 669 million in 2016)
- Altitude tower above water: 552 feet (168 m)
- Max. the depth of the tower under water: 210 feet (64 m)
- Water depth below center of bridge, 250 feet (76 m)
- The total length of cable in the main cable: 42,000 miles (68,000 km).
- Total vehicle crossings, 2005: 4,236,491 (average 11,608 per day)
- Speed ​​limit: 45 miles per hour (72 km/h) for passenger cars, 20 miles per hour (32 km/h) for heavy trucks. Large trucks should also leave a distance of 500 feet (150 m) in front.
Jobs and major crash victims
Five workers were killed during the construction of the bridge.
- Diver Frank Pepper climbed too fast from 140 feet (43 m) deep on September 16, 1954. Despite being rushed to the decompression room, a forty-six-year-old man died of a bend.
- James LeSarge was twenty-six years old losing his balance on October 10, 1954, and falling into caisson. He fell 40 feet (12 m) and possibly died of a head injury caused by a collision with a cross-linked steel beam inside caisson. Albert Abbott died on October 25, 1954. The forty-year-old boy fell four feet (1.2 m) into the water while working on an 18-inch (46 cm) wide beam. Witnesses suspect he had a heart attack.
- Jack Baker and twenty-eight-year-old Robert Koppen died in a catwalk collapsing near the north tower on June 6, 1956. Koppen's body was never found. Because both are their first day at work.
The five men were immortalized on a plaque near the north end of the bridge (Bridge View Park). Contrary to folklore, no body is embedded in the concrete.
One worker has died since the bridge is over. Daniel Doyle fell from 60 to 70 feet (18 to 21 m) from the scaffold on August 7, 1997. He survived the fall but became a victim of water temperature 50Ã, Â ° F (10Ã, Â ° C). His body was found the next day at 95 feet (29 m) of water.
Two vehicles fell off the bridge.
- On September 22, 1989, Leslie Ann Pluhar died when her 1987 Yugo fell on a 36 inch (91 cm) tall fence. The combination of strong winds and excessive speed was initially blamed. The investigation then indicates the driver has stopped his car on an open steel grating in the bridge span and that a gust of wind through the lattice blew his vehicle off the bridge, though this is not supported by the measured wind speeds recorded at and around the bridge. at the time of the accident.
- On March 2, 1997, Richard Alan Daraban piloted the Ford Bronco in 1996. It was later determined to commit suicide.
On September 10, 1978, a small private plane carrying US Marine Corps Major Virgil Osborne, Captain James Robbins and Captain Wayne W. Wisbrock crashed into one of the cable hanging cables as they flew in thick fog. The impact tore the wings off the plane, which then fell into the Strait of Mackinac. The three men were killed.
Since this bridge is inaccessible to pedestrians, the suicide by jumping from the bridge has been rare, with the latest confirmed cases occurring on December 31, 2012. There were about a dozen suicides by people jumping off the bridge.
Cross the bridge
Some individuals have difficulty crossing the bridge, a phenomenon known as gephyrophobia. The Mackinac Bridge Authority has a Driver Assistance Program that provides drivers for those with gephyrphobia, or anyone more comfortable having others who drive them across. Over a thousand people use this service every year. Those interested can arrange, either by phone or with toll collectors, to have their car or motor driven to the other end. There are no additional charges for this service. Bicycles and pedestrians are usually not allowed on the bridge. Exceptions are allowed for motorists from two annual bike tours. Every day, at a cost of $ 5.00, the Authority will transport cyclists and vehicles across the bridge.
Tourists across from Mackinac Bridge can listen to AM radio broadcasts that tell the history of the bridge and provide updates on driving conditions.
Bridge Walk
The Mackinac Bridge Walk has been held every year since 1958, when headed by Governor G. Mennen Williams. The first trip was held during the Bridge Service Ceremony held at the end of June, and was held on Labor Day since 1959. The school bus from the local district transported pedestrians from Mackinaw City to St. Ignace to start running. Thousands of people, traditionally led by the Michigan Governor, cross the five mile (8 km) range on foot from St. John's. Ignace to Mackinaw City. Before 1964, people walked on the Bridge from Mackinaw City to St. Ignace. Prior to 2017, two bridge lines will remain open to public transport traffic; This policy was changed in 2017 to cover the entire bridge to public vehicle traffic during the event. The Bridge Walk is the only day of the year where climbers can climb this North Country National Scenic Trail.
Tourism
During the summer, the Upper Peninsula and Mackinac Bridge have become major tourist destinations. In addition to visitors to Mackinac Island, the bridge attracts interest from a diverse group of tourists including bridge enthusiasts, bird watchers, and photographers.
In media
On June 25, 1958, to coincide with the 1958 1958 opening celebration of November 1957, the US Postal Service (USPS) released a 3 Â ¢ warning stamp featuring a newly constructed bridge. It was titled "Connecting Michigan Peninsulas" and 107,195,200 copies were published. USPS once again honored the Mackinac Bridge as the subject of priority $ 4.90 priority stamps in 2010, which went on sale Feb. 3. The authority of the bridge and MDOT launched a stamp, which featured the landmark "gulls' eye view, by passing it. freighter below. Artist Dan Cosgrove works from panoramic photographs to create works of art. This is one of the few designs Cosgrove has produced for the USPS.
On April 24, 1959, Captain John S. Lappo, an officer at the Strategic Air Command, operating from Lockbourne AFB flew his Boeing B-47 Stratojet under the bridge. After the General military court, he was sentenced to life.
The long documentary entitled Build Mighty Mac was produced by Hollywood filmmaker Mark Howell in 1997 and featured on PBS. The program featured many interviews with key people who built the structure and included returning a 16mm color recording of the bridge construction.
The history and construction of the bridge was featured in the 2003 episode of the TV show Channel History of Modern Marvels.
On July 19, 2007, the Detroit Science Center unveiled an 80-foot (24 m), 19-foot (5.8 m) scale model of the Mackinac Bridge. The exhibition was part of the 50th anniversary celebration of the country's bridge. Sherwin-Williams provides original Mackinac Bridge colored paint for the project.
The bridge and the maintenance crew were featured in the episode of the Discovery Channel TV Entertainment show on Gross Jobs on August 7, 2007. Host Mike Rowe and the crew spent several days filming the episode in May 2007.
MDOT also featured a bridge on the cover of a 2007 state highway map to celebrate its 50th anniversary.
See also
- List of longest suspension bridges
Note
References
The work cited
Further reading
External links
- Mackinac Bridge Authority
- Long Comparison
- Mackinac Bridge photographing and facts
- Keep an eye on Mighty Mac, Starting Point, 2007
- Web cams that monitor Mackinac Bridge
- A view over the iconic Mackinac Bridge connecting two Michigan peninsula, 2014
- Historical American Engineering Record (HAER) no. MI-329, "Mackinac Strait Suspension Bridge"
Source of the article : Wikipedia
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