Tech Directions - April 2008 - (Page 9)

technology’s past Dennis Karwatka d.karwat@morehead-st.edu The Hoosac Tunnel It was the first significant tunnel built in America. Its nearly five-mile length went through the Hoosac Mountain in the Berkshires of western Massachusetts, just east of North Adams. The Hoosac Tunnel project began in 1851 and opened for rail traffic in 1875. The Albany and Western Railroad operated between Boston and the Hudson River, which connected with the Erie Canal at Albany. The Erie Canal served as the gateway to America’s interior and was the most important transportation route in the country. The railroad’s tracks crossed the Berkshire Mountains near Pittsfield, MA, at a particularly steep and circuitous section. This meant the locomotives could not pull many loaded cars. Because Boston was losing business to rival ports, political leaders in Massachusetts looked for other rail options. A tunnel through the Hoosac Mountain seemed the most feasible solution. The state of Massachusetts approved the project in the amount of $2 million. Promoters ceremoniously broke ground in 1851 at the tunnel’s east portal. Hopes ran high for speedy completion because the workers had the use of a new type of tunnelboring machine. A steam engine rotated bits that cut a groove around a 24'-diameter circle. Explosive gunpowder then loosened the central rock core. The device did not work as expected, and the workers returned to more traditional methods that used hand drilling and gunpowder. Using a sledgehammer and an iron rod, they hammered 3'deep holes into the tunnel face. Gunpowder placed in the holes exploded out chunks of rock, which the workers removed before repeating the process. The maximum drilling rate was no more than 60' per month. One early decision was to dig a large vertical shaft along a ridge and about halfway between the tunnel’s portals. The hole was over 1,000 feet deep and wide enough to send workers down. It allowed digging at four tunnel faces at the same time. That central shaft is now used for tunnel ventilation. No aspect of the Hoosac Tunnel project was more significant than its use of compressed-air equipment. Pneumatic tools first saw use in the construction of the Mount Cenis Tunnel through the Alps between France and Italy, which began in 1857. Many of the boring tools used in that project operated with compressed air. In the United States, in 1866, Fitchburg technologist Charles Burleigh designed The Hoosac Tunnel in 1915, a pneumatic drill showing its original two tracks that was both less, it stands within the front ranks lightweight and durable. His of all the massive projects of its carriage-mounted percussion drills time. operated at 250 strokes per minute. The air came from a twin-cylinder compressor powered by water that References flowed in the nearby Deerfield River. Gladden, Washington. (1870, DecemExhaust air from the drills had the ber). The Hoosac Tunnel. added benefit of providing some Scribner’s Magazine, 143–159. ventilation. The Hoosac Tunnel Jacobs, David, & Neville, Anthony E. equipment helped launch the Ameri(1968). Bridges, Canals, and Tuncan pneumatic tool industry. nels. American Heritage PublicaAs the tunnel drillers moved tions. toward each other, shaft alignment Meyer, William B. (1985, Fall). Ameriwas always a concern. A small error can Heritage of Invention and in heading could cause shafts to Technology, 53–57. miss each other entirely. But when the Hoosac Tunnel drillers finally Dennis Karwatka is professor met each other in 1873, the offset emeritus, Department of Industrial was only 1-1/2" horizontally and 9/ and Engineering Technology, More16" vertically. By contrast, the head (KY) State University. slightly longer Mount Cenis Tunnel had an offset of 18". Two sets of tracks were laid and the Hoosac Tunnel opened to train traffic in 1875. Its final cost was about $17 million. The tunnel was enlarged in 1927 and changed to a single track in the 1950s. Still in use, it measures 4-3/4 miles in length and is the fourth-longest railway tunnel in America. Impressive construction projects of the 19th century usually dominate their surroundings. The Brooklyn Bridge and the Washington Monument are two examples. But the superbly engineered Hoosac Tunnel is inconspicuously located in northwestern Massachusetts. Nonethe- www.techdirections.com TECHNOLOGY’S PAST 9 Library of Congress http://www.techdirections.com

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Tech Directions - April 2008 Technically Speaking Contents Direct from Washington The News Report Technology's Past Technology Today Mastering Computers A Bridge to the Future Aeronautics Study Takes Off! Glider Design for Beginners Project Engineer in the Heavy Construction Industry for Renewable Energy Annual Buyers' Guide More than Fun

Tech Directions - April 2008

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