The Mackinac (pronounced Mackinaw) Bridge is a very special bridge for a lot of reasons so it made sense for me to use it for Jake’s Sunday Post for this week. I talked about how important it is from the perspective of people living in the Upper Peninsulas of Michigan in an earlier post you can find here. It is a beautiful bridge that is situated in a beautiful setting, spanning the Straits of Mackinac that connects the very large fresh-water bodies of Lake Michigan and Lake Huron. It feels like a jewel sparkling in the rural and sometimes rugged beauty of northern Michigan.
When it was finished in 1957 it was the longest suspension bridge in the world. Now the Akashi Kaikyo Bridge in Japan (built in 1998) is the longest with a total suspension of 12,826 feet. The Great Belt Bridge in Halsskov-Sprogoe, Denmark (built in 1998) is the second longest with a total suspension of 8,921 feet. The Mackinac Bridge is the longest suspension bridge in the western hemisphere, having a suspension of 8,614 feet. The total length of the Mackinac Bridge is 26,372 feet or 5 miles.
A northern Michigan newspaper reported in early 1884 that the experiment to provide all-year service across the Straits by boat had failed, and a bridge or tunnel would be required if there were to be travel between the peninsulas. Ideas were proposed in the ensuing years, including a floating tunnel. In 1923 the Michigan legislature ordered the State Highway Department to establish a ferry service at the Straits. Within five years traffic on this facility became so heavy that the governor ordered a study of bridge feasibility. This was a huge undertaking because of the depth of the water, the strong current, and the harsh winter conditions. It would be expensive. Interest was renewed several times in the ensuring years until work was finally begun in spring of 1954. The bridge was designed by the great engineer Dr. David B. Steinman. It opened to traffic on November 1, 1957 according to schedule, despite the many hazards of marine construction over the turbulent Straits of Mackinac.
The engineering of this bridge is mind-boggling (not surprising seeing I marvel at all engineering). All suspension bridges are designed to move to accommodate wind, change in temperature, and weight. It is possible that the deck of the Big Mac at center span could move as much as 35 feet (east or west) due to severe wind conditions. The deck does not swing or “sway” but rather moves slowly in one direction based on the force and direction of the wind. After the wind subsides, the weight of the vehicles crossing will slowly move it back into center position. As I said, this is one amazing bridge.
Information for this post came from the Michigan Department of Transportation website, where you can obtain more interesting facts about the bridge and see more pictures. http://www.mackinacbridge.org/about-the-bridge-8/
To see more photos of bridges, click on this link: http://jakesprinters.wordpress.com/2013/06/23/sunday-post-bridge/