National Geographic : 1960 Apr
KODACHROMEBY NATIONALGEOGRAPHICPHOTOGRAPHERB. ANTHONYSTEWART© N.G .S . Floating Bridge: 100,000 Tons of Concrete and Steel Rest on Water World's heaviest structure afloat, the 20-year-old span saves travelers on U. S. Highway 10 a 14-mile detour around Lake Washington, whose 200-foot depths and unstable floor made a conventional bridge unfeasible. Held by massive 65-ton anchors, the four-lane roadway sways less than an inch in rough weather. A retractile unit in the span 514 permits passage of ocean vessels. This aerial view looks west from Mercer Island.