As the new State Route 520 floating bridge nears completion in Seattle, the 31 original bridge pontoons are ready for removal. Rather than breaking them up, the Washington Department of Transportation (WSDOT) will tow them through the Seattle ship canal and Ballard Locks to Puget Sound.  In an epic display of recycling, they will be delivered to True North Projects, which will market them around the world as floating docks, storage platforms, or breakwaters.  The WSDOT website has background about the SR 520 project in general and the True North website has lots of information about the pontoons’ construction and potential uses.  If you want a pontoon, this is your opportunity.  Even if you don’t, you may be interested in how pontoons are built and how they can be used when not supporting a highway.

Lake Washington Bridge 7-25-16

The pontoons for the new bridge were built in various places, as far away as Aberdeen on Washington’s Pacific Coast, and towed to Seattle. Upon arrival, some were found to be cracked and leaking.  A panel of experts studied the problem and recommended a solution.  A combination of repairs and modified casting methods was implemented, with the result that the new pontoons are in place and in use.  This is a reminder that what might at first appear to be a relatively simple task (make a big concrete box to support a bridge) can lead to unexpected and complex problems.  But smart and experienced people can solve problems, for which we should all be grateful.