SR 520 - Pontoon Float-out 101 - Pontoon Construction Project - July 2012

WSDOT is building pontoons in Aberdeen that will be used for the new SR 520 floating bridge. Floating out these massive concrete structures is a complicated process, and this animation walks you through each of the steps.
Visit our website for more information: wsdot.wa.gov/Projects/SR520Bridge

[@jamiewalshdesigns]

Nice animation. Good job.

[@Being_Unidirectional]

How these huge pontoons float?

[@wsdot]

Good question. Floating bridges are made of large water-tight concrete pontoons connected rigidly end-to-end, upon which the roadway is built. Despite their heavy concrete composition, the weight of the water displaced by the pontoons is equal to the weight of the structure (including all traffic), which allows the bridge to float.

[@Being_Unidirectional]

@@wsdot Still i didn't understand 🙏🏼

[@Being_Unidirectional]

@@wsdot i understand but how can tje weight of pontoons(made of concrete) be equal to weight of water... Is thier density same?

[@wsdot]

@@Being_Unidirectional While the outside structure of the pontoons is made of concrete, the pontoons are made up of multiple hollow, watertight cells. Since the pontoons are so large and deep, they displace a lot of water. This volume of water displaced weighs more than the weight of the pontoons, which enables the pontoons to float. (Think Icebergs!) The hollow cells inside the pontoons helps keep the overall weight low enough to float. If you want to learn more, we'd recommend researching the Archimedes' Principle - that's the science behind how pontoons float!

[@wsdot]

Please keep comments related to the video, comments not related to this video have been removed. You can learn more about our comment policy here: wsdot.wa.gov/Policy/blog.htm