Although Washington State is ground zero for the most numerous and biggest floating bridges, it's by no means the only place you'll find them. Countries around the world maintain their own permanent, pontoon-based constructions.
As with the Seattle area, in Georgetown, Guyana, water (in the form of the Demerara River) was making it hard for the city to grow economically. So in 1978, Guyana built the Demerara Harbor bridge to connect communities and allow for more commercial expansion.
At 1.2 miles (2 kilometers) long, it's the fourth-longest pontoon bridge in the world. It supports a two-lane road and incorporates 122 steel pontoons. Like its Washington cousins, this bridge has suffered its share of problems: deterioration due to lack of maintenance, ship collisions and the sinking of sections due to heavy tides.
As in Washington, Norway has its share of water near population centers. That fact helped spawn a need for the Nordhordland Bridge, which has a floating section that's 4,088 feet (1,246 meters) long. There are 10 pontoons under the bridge of varying sizes, which help the deck cross a fjord and connect to a more traditional, cable-stayed bridge.
Not all currently existing bridges are so large or so new. The Dongjin Bridge in China, for example, has been in use since the Song Dynasty, which took place between 960 and 1279. This (400 meter) bridge still uses wooden boats -- about 100 of them -- to provide buoyancy for the wooden plank deck. The boats are secured to each other with chains.
Regardless of their construction or age, floating bridges have been a part of human transportation for centuries. Not only have they conquered many winds and waves, but they've also stood the test of time. And they'll be around for a long time to come, as long as people still need to find their way across deep waters.
- Army Technology. "CNIM." Army-technology.com. (Sept. 5, 2011) http://www.army-technology.com/contractors/engineering/cnim1/
- Bridge Hunter. "Brookfield Floating Bridge." Bridgehunter.com. (Sept. 5, 2011) http://bridgehunter.com/vt/orange/brookfield-floating/
- Bridge Watcher. "Amazing Bridges of China." Bridgewatcher.com. Apr. 10, 2011. (Sept. 5, 2011) http://bridgewatcher.com/amazing-bridges-of-china/
- Chen, Wai-Fah and Lian Duan. "Bridge Engineering Handbook." CRC Press. 1999.
- China Unique Tour. "The Four Most Famous Ancient Bridges in China." Chinauniquetour.com. (Sept. 5, 2011)http://www.chinauniquetour.com/html/all/200992/arts-6169.html
- Davis, William Stearns. "Readings in Ancient History." Allyn and Bacon. 1912.
- Defence Research and Development Organisation. "Amphibious Floating Bridge and Ferry System." Drdo.gov.in. (Sept. 5, 2011) http://drdo.gov.in/drdo/English/index.jsp?pg=Affs.jsp
- Engineering Sights. "Albert D. Rossellini (Evergreen Point) Floating Bridge." Engineeringsights.org. (Sept. 5, 2011) http://www.engineeringsights.org/SightDetail.asp?Sightid=126&id=&view=k&name=&page=26&image=0
- Global Security. "Improved Float Bridge (Ribbon Bridge)." Globalsecurity.org. (Sept. 5, 2011) http://www.globalsecurity.org/military/systems/ground/rb.htm
- Goodall, David M. "27 Years of Bridge Engineering with Federal Highway Administration." Fhwa.dot.gov. April 7, 2011. (Sept. 5, 2011) http://www.fhwa.dot.gov/infrastructure/blazer16.cfm
- Harrell, Debera Carlton. "Disaster Strikes the 520 Bridge in Video Simulation." Seattlepi.com. April 4, 2007. (Sept. 5, 2011) http://www.seattlepi.com/local/transportation/article/Disaster-strikes-the-520-bridge-in-video-1233367.php
- Herodotus. "The Histories of Herodotus." The G.P. Putnam's Sons. 1885.
- History Channel. "Military Bridge." History.com. (Sept. 5, 2011) http://www.history.com/topics/military-bridge
- History Link. "Lacey V. Murrow Memorial Bridge (Lake Washington Floating Bridge) Sinks on Nov. 25, 1990." Historylink.org. (Sept. 5, 2011) http://www.historylink.org/index.cfm?displaypage=output.cfm&file_id=2002
- History Link. "Hood Canal Bridge Sinks During a Severe Storm on Tuesday, Feb. 13, 1979." Historylink.org. (Sept. 5, 2011) http://www.historylink.org/index.cfm?DisplayPage=output.cfm&File_Id=5501
- Lahanas, Michael. "Ancient Greek Inventions." Mlahanas.de. (Sept. 5, 2011) http://www.mlahanas.de/Greeks/InventionsF.htm
- Land of Six Peoples. "Twenty-Five Years On…What's Next for the Demerara Harbour Bridge?" Landofsixpeoples.com. July 22, 2003. (Sept. 5, 2011) http://www.landofsixpeoples.com/news303/ns3072213.htm
- Macaulay, G. C. "The History of Herodotus." Gutenberg.org. (Sept. 5, 2011) http://www.gutenberg.org/files/2456/2456-h/book7.htm
- Mercer Island Historical Society. "The Concrete Floating Bridge." Mihistory.org. (Sept. 5, 2011) http://www.mihistory.org/bridge.html
- Osborn, Kris. "Army Floating Bridge Helps Gulf of Mexico Oil Spill." Ng.mil. May 27, 2010. (Sept. 5, 2011) http://www.ng.mil/news/archives/2010/05/052810-Army.aspx
- Troyano, Leonardo Fernandez. "Bridge Engineering: A Global Perspective." Thomas Telford Publishing. 2003.
- Vermont Public Radio. "Brookfield Floating Bridge Off Limits for Vehicles." Vpr.net. May 16, 2008. (Sept. 5, 2011) http://www.vpr.net/news_detail/80561/
- Washington State Department of Transportation. "SR 104 – Hood Canal Bridge Project – Complete March 2010." Wsdot.wa.gov. (Sept. 5, 2011) http://www.wsdot.wa.gov/projects/sr104hoodcanalbridgeeast/
- Washington State Department of Transportation. "SR 104 – Hood Canal Bridge – 2009 Frequently Asked Questions." Wsdot.wa.gov. (Sept. 5, 2011) http://www.wsdot.wa.gov/Projects/SR104HoodCanalBridgeEast/faq.htm#howmany
- Washington State Department of Transportation. "SR 520 Bridge Facts." Wsdot.wa.gov. (Sept. 5, 2011) http://www.wsdot.wa.gov/projects/sr520bridge/questions.htm
- Washington State Department of Transportation. "SR 520 Program – Costs, Funding and Tolling." Wsdot.wa.gov. (Sept. 5, 2011) http://www.wsdot.wa.gov/Projects/SR520Bridge/financing.htm
- Washington State Legislature. "I-90 Bridge Technical Review." Leg.wa.gov. April 8, 2008. (Sept. 5, 2011) http://www.leg.wa.gov/JTC/Meetings/Documents/I90_Technical_Review.pdf
- Web Archive. "The Nordhordland Bridge." Web.archive.org. 1994. (Sept. 5, 2011) http://web.archive.org/web/20060209233657/http://www.vegvesen.no/region_vest/prosjekter/nordhordlandsbrua/brosjyre_1994.pdf