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The original Nalley Valley Viaduct was built from 1969 to 1971 by Donald M. Drake Company of Portland, Oregon for $3.67 Million. Photo of Nalley Valley in the early stages of building the original SR 16/I-5 Nalley Valley interchange.The Viaduct's tetrapod structures weigh nearly 400 tons each.The SR 16/I-5 Nalley Valley interchange was constructed with unique tetrapod (four-legged) columns, the first of their kind in Washington.The original Nalley Valley Viaduct and interchange was open to traffic after a ribbon-cutting event October 29, 1971. Facing the camera, from left to right, Gene Lewis (Master of Ceremonies), Mr. Kerslake (District 3 Engineer), Mr. Whitacre (President Tacoma C. of C.), Mr. Johnson (Mayor of Tacoma) and Mr. Parker (State Highway Commission).