Mackinac Bridge

The Mackinac Bridge is a suspension bridge spanning the Straits of Mackinac to connect the Upper and Lower Peninsulas of the U.S. state of Michigan. Opened in 1957, the 26,372-foot (8.038 km) bridge (familiarly known as "Big Mac" and "Mighty Mac") is the world's 19th-longest main span and the longest suspension bridge between anchorages in the Western Hemisphere.

The bridge opened to traffic on November 1, 1957. The Mackinac Bridge Authority is committed to preserve and maintain the State of Michigan’s single largest asset and one of the world’s leading suspension bridges to provide safe, pleasurable and expedient passage over the Straits of Mackinac for economic benefit and improved quality of life. The Mackinac Bridge is currently the fifth longest suspension bridge in the world. The Mackinac Bridge is the longest suspension bridge in the western hemisphere. The total length of the Mackinac Bridge is 26,372 feet. The length of the suspension bridge (including anchorages) is 8,614 feet. The length from cable bent pier to cable bent pier is 7,400 feet. Length of main span (between towers) is 3,800 feet.

The width of the roadway is 54 feet. The outside lanes are 12 feet wide (2), the inside lanes are 11 feet wide (2), the center mall is 2 feet wide, and the catwalk, curb and rail width is 3 feet on each side – totaling 54 feet. The stiffening truss width in the suspended span is 68 feet wide making it wider than the roadway it supports.The height of the roadway at mid-span is approximately 200 feet above water level. The vertical clearance at normal temperature is 155 feet at the center of the main suspension span and 135 feet at the boundaries of the 3,000 ft. navigation channel.

All suspension bridges are designed to move to accommodate wind, change in temperature, and weight. It is possible that the deck at center span could move as much as 35 feet (east or west) due to high winds. This would only happen under severe wind conditions. The deck would not swing or “sway” but rather move slowly in one direction based on the force and direction of the wind. After the wind subsides, the weight of the vehicles crossing would slowly move it back into center position.

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