Thursday, January 12, 2012
Seattle and its suburbs are divided by Lake Washington, a 33.8-square-mile remnant of the ice ages. The lake presents a formidable obstacle to would-be bridge builders. It is too deep, and its bed too soft, to be spanned by a normal bridge. So almost 50 years ago, Washington state opted for a bridge that floats -- a 7,578-foot monster of a bridge on pontoons.
Now, as the bridge nears the end of its design life, the state is building a brand-new replacement floating bridge. At 7,710 feet, it will be even longer than the old record holder. A single one of its hulking concrete pontoons will be as long as a football field and weigh as much as 23 Boeing 747 jets.