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Show Pipe Arch Bridge. An engineering curiosity, said to be unique to this country and ti have only one parallel In Europe, Is the pipe arch bridge over the Sudbars river which carries Boston's water supply. The span is eighty feet, and the steel pipe, seven and one-half feet In diameter rises five and one-half one-half feet above the horizontal at the center. The pressure on the abutments abut-ments when the pipe Is filld with water Is great and is resisted by a mass of concrete forty feet thick behind be-hind each abutment. Across the curved tops runs a hand-railed foot bridge. The steel of the pipe in the arched portion is five-eighths of an inch in thickness. |