Godfrey, Kneeland, Jr. (ed.) / The Wisconsin engineer
Volume 59, Number 4 (January 1955)
White, Richard N.
The Mackinac Straits bridge, pp. 20-22
-U. S. Steel Photo Fig. 1.-Two main steel towers rise majestically 552 feet above water from piers founded on rock approxi- mately 195 feet below lake level. These main towers support cables for a center span of 3800 feet, second only to the 4200 feet of the Golden Gate Bridge in San Francisco. The total length of the bridge and approaches is 26,195 feet, while the suspension bridge, 8,614 feet from anchorage to anchorage, is the longest in the world. The Mackinac Straits Bridge A GREAT MAN-MADE LINK NOW BEING BUILT BETWEEN UPPER MICHIGAN AND THE LOWER PART OF THAT STATE by Richard N. White, ce'56 A Short History of Bridges Undoubtedly the first bridges were formed by -Mother Nature-fallen logs across streams, natural arches formed bv erosion, and similar devices. Man soon came to imitate these structures, and then started to improve on them and devise new and different types of bridges. India was the birthplace of the modern sus- pensionl bridge an(l the cantilever bridge. Mesopotamia, in 4000 B.C., produced the first true arch bridge; and the Romans, who usually needed many bridges in a short time, built the pontoon and timber trestle bridges during their military conquests. After Rome the Church became the chief bridge- lbuilders because of the unruly order and dangerous traveling conditions. As the Renaissance came into being, Leonardo da Vinci drew plans for portable and bascule bridges, and Palladio first used the truss, which is the framework of most modern bridges. Many large masonry arch bridges were being constructed at this time, especially in Paris. It was also in the Renaissance period that the bridgebuilders became known as civil engineers and gained stature in the eyes of the public. It was not until the 18th century that bridges were designed using some type of scientific analysis. The first engineering school was headed by Jean Perronet who has been called the father of modern bridgebuild- ing. A few years later iron and wrought iron came into use as a building material, and many new wrought iron truss type bridges were constructed. However, during the 1870's and 1880's about 25 railroad bridges THE WISCONSIN ENGINEER 2()
This material may be protected by copyright law (e.g., Title 17, US Code).| For information on re-use, see http://digital.library.wisc.edu/1711.dl/Copyright