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Drinking Water Week
American Water Works Association (5/6)
Drinking Water Week, May 4-10, is a unique opportunity for water professionals and the communities they serve to join together to recognize the vital role water plays in our daily lives.
American Wetlands Month
U.S. Environmental Protection Agency (5/2)
This May will mark the 18th anniversary of American Wetlands Month, a time when EPA and its partners celebrate the vital importance of wetlands to the Nation's ecological, economic, and social health. It is also a great opportunity to discover and teach others about the important role that wetlands play in our environment and the significant benefits they provide.
Great Lakes Regional Research Information Network (GLRRIN)
GLIN's May 2008 Site of the Month (5/1)
Established in 2006 by NOAA Sea Grant, GLIN and regional partners, GLRRIN provides a powerful means to foster collaboration, acquire funding, highlight research needs and issues, and increase the overall impact of Great Lakes research. GLRRIN is a free service and offers research-related news and upcoming events, and profiles of Great Lakes researchers and their current projects.
Mother Earth Water Walk
(4/28)
Two Anishinawbe Grandmothers, and a group of Anishinawbe Women and Men have taken action regarding the water issue by walking the perimeter of the Great Lakes. The 2008 Lake Michigan walk kicked off April 26.
Shipwrecks and Maritime Tales of the Lake Erie Coastal Ohio Trail
Ohio Sea Grant (4/24)
The shipwrecks within this website are a mere sampling of the hundreds of shipwreck sites located in the depths of Lake Erie. The goal is to make the visitor aware of the rich maritime history which lies beneath the surface of Ohio's Lake Erie.
Michigan Wildlife Conservancy
(4/21)
The Michigan Wildlife Conservancy provides the technical and financial assistance that landowners and managers need to restore and maintain wildlife habitat on their own land.
What's going on in your neighborhood this month? Meet other people and learn together at recreational and educational events! Our new dynamic calendar is updated daily with current educational events.
2 | The construction period: 1954-57
Because the bridge was in a remote area, financing the project was slow and difficult. The total cost of the project was upwards of $100 million (originally estimated at $70 million).
Construction began in 1954 and during the 42 months that followed hundreds of men worked on the various phases of the bridge construction.
The first step was to sink the large, double-walled cylinders that form the bases of the two main tower piers. These cylinders are called caissons (cay-säns). The caissons had to be sunk down into the bedrock on the lake floor, a great challenge for the divers involved.
When the foundation pillers were finished, the iron workers were brought in to string the massive cabling network! More than 500 workers were housed in St. Ignace, Mich., during this construction period.
A "catwalk" made of cyclone fence enabled the workers to navigate between the bridge towers, high above the lake below.
When finished, the cables were close to 25 inches in diameter. Each cable consists of 340 wires banded into a single strand; 37 strands are then assembled into a single cable. To complete the job and add extra strength, a covering is spun around each finished cable. More than 42,000 miles of wire were used in the two main bridge cables!
The last step was to construct the road surface. The inner lane on the middle span of the bridge includes an open grid riding surface. This was installed to allow wind forces to move through the bridge.
Images: Erecting the north tower and adding trusses and cables, courtesy "Picture Story of the Mackinac Bridge," 1978 Voyager Press; the Mighty Mac close to completion in 1956, courtesy Albert Ballert.
