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Buy the "Great Projects" videos and companion book at ShopPBS. |
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Keeping Traffic Moving Depressing the Central Artery posed an altogether different problem in tunneling: Here the engineers had to dig a tunnel under the old elevated roadway. The new, underground roadway had to be wider than the old roadway above. And, the artery had to remain in place to carry traffic. To solve the problem, engineers built two buried walls along the entire length of the Central Artery and laid giant beams from one wall to the other to prop up the highway. |
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  How engineers contained and controlled the Colorado and Mississippi rivers. Thomas Edison lights up New York City; Sam Insull brings power to Chicago; and TVA electrifies rural America Constructing the George Washington Bridge Putting a major highway under Boston  |
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