“Imagine such a structure staggering and lurching in the grip of a real storm! Imagine what would happen to automobiles trying to cross it! But worst of all, imagine what would happen if the thing came apart!”—The Seattle Times editor C.B. Blethen on the construction of a floating bridge[1]
“C.E. Andrew, the project engineer, claimed it would be impossible to build a conventional bridge anchored on piers between Mercer Island and the western lake shore due to the depth of the water, which exceeds 200 feet in places.
The soft, muddy bottom of Lake Washington would require piers at least 350 feet, he said, longer than those used for the San Francisco–Oakland Bay Bridge.”[2]
Lake Washington is a deep lake with a soft muddy bottom, this makes conventional bridge design completely impossible. Homer M. Hadley a structural engineer was the first to come up with a solution to the problem: a bridge that floats. At first he was laughed at, the idea was called “Hadle’s Folly” by investment bankers he attempted to obtain funds from. But then he took his idea straight to Lacy V. Murrow, State Highway Director, who loved it.
“Designed by the engineer Homer Hadley (1885–1967), the bridge floats on hollow concrete pontoons. This technology was highly innovative at the time.”
““If Seattle will stop arguing over what it wants and decide on something ... funds will be available,” [senator] Magnuson said. “There is no objection whatever in Washington, D.C., to a pontoon bridge.” It came down to a Seattle City Council vote – 5 in favor, 4 against. “Hadley’s Folly” or Murrow’s bridge, it would be built.”[4]
There was much controversy over bridging Lake Washington with a floating bridge. People had 2 main fears, that the bridge may sink in a storm,and that it would be an eyesore. There was much campaigning for and against the bridge and it was approved by the Seattle City Council by a very narrow margin.
The bridge was built using floating hollow concrete pontoons linked together by steel cable and anchored into the lake bed by large anchors. How does it work?“Construction began on Jan. 3, 1939. The bridge – at the time the largest floating object ever built, and the only floating concrete bridge – would carry its first cars in 18 months.”[4]
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