Mackinac Island in Mackinac County, Michigan — The American Midwest (Great Lakes)
The Mackinac Bridge
The Mackinac Bridge is a magnificent sculpture of steel, wire and concrete. Two support cables flow like giant waves over the main towers which rise more than 550 feet above the Straits of Mackinac. These cables, composed of thousands of strands of wire tightly wrapped together, are anchored in giant concrete blocks which are 8,614 feet apart, making it the longest single-unit suspension bridge in the western hemisphere.
During deer hunting season before the bridge was built, automobiles lined up from Mackinaw City to Cheboygan - a distance of 15 miles! - waiting to cross the straits in car ferries.
Erected by Mackinac Associates and Mackinac State Historic Parks.
Location. 45° 52.658′ N, 84° Touch for map. Marker is located in a pull-out on the west side of the highway, overlooking the Straits of Mackinac and the Mackinac Bridge. Marker is in this post office area: Mackinac Island MI 49757, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within 3 miles of this marker, measured as the crow flies. The Ice Bridge (here, next to this marker); British Landing (a few steps from this marker); Post Cemetery (approx. 1.8 miles away); Skull Cave (approx. 1.9 miles away); Fort Holmes (approx. 1.9 miles away); a different marker also named Fort Holmes (approx. 1.9 miles away); Grand Hotel (approx. 2.1 miles away); Mackinac Conference (approx. 2.1 miles away). Touch for a list and map of all markers in Mackinac Island.
Also see . . .
1. History of the Bridge. The five-mile bridge, including approaches, and the world’s longest suspension bridge between cable anchorages, was 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 bridge was officially begun amid proper ceremonies on May 7 & 8, 1954, at St. Ignace and Mackinaw City. (Submitted on April 5, 2019, by Cosmos Mariner of Cape Canaveral, Florida.)
2. History of the Bridge Design (Wikipedia). The design of the Mackinac Bridge was directly influenced by the lessons from the first Tacoma Narrows Bridge, which failed in 1940 because of its instability in high winds. Steinman 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 design of the Mackinac Bridge. The road deck is shaped as an airfoil to provide lift in a cross wind, and 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 of up to 150 MPH. (Submitted on April 5, 2019, by Cosmos Mariner of Cape Canaveral, Florida.)
Categories. • Bridges & Viaducts •
Credits. This page was last revised on April 5, 2019. This page originally submitted on April 5, 2019, by Cosmos Mariner of Cape Canaveral, Florida. This page has been viewed 99 times since then. Photos: 1, 2, 3, 4. submitted on April 5, 2019, by Cosmos Mariner of Cape Canaveral, Florida.