Lacey V. Murrow Memorial Bridge (right), looking east toward Mercer Island

The Lacey V. Murrow Memorial Bridge is the second longest floating bridge in the world, at 6,620 feet (2,019 meters). It carries the eastbound lanes of Interstate 90 across Lake Washington from Seattle to Mercer Island, Washington. The original two-way, four-lane toll bridge was designed by the engineer Homer Hadley (1885-1967) and constructed of reinforced concrete in 1940. Tolls were removed in 1946. It sank in a storm on November 25, 1990, while it was undergoing refurbishing & repair. The current bridge was built in 1993. The Interstate 90 floating bridges across Lake Washington, looking east from Seattle toward Mercer Island. ... The Interstate 90 floating bridges across Lake Washington, looking east from Seattle toward Mercer Island. ... A pontoon bridge Pontoon bridges are floating bridges supported by floating pontoons with sufficient buoyancy to support the bridge and dynamic loads. ... t Interstate 90 is the longest interstate highway in the United States. ... Lake Washington is the second largest natural lake in Washington state, USA, behind Lake Chelan, and the largest lake in King County. ... City nickname Emerald City City bird Great Blue Heron City flower Dahlia City mottos The City of Flowers The City of Goodwill City song Seattle, the Peerless City Mayor Greg Nickels County King County Area   - Total   - Land   - Water   - % water 369. ... Mercer Island is a city located in King County, Washington. ... Paying toll on passing a bridge. ... 1940 was a leap year starting on Monday (link will take you to calendar). ... November 25 is the 329th (in leap years the 330th) day of the year in the Gregorian calendar. ... 1990 is a common year starting on Monday of the Gregorian calendar. ... 1993 is a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ...

Formerly known as the "Lake Washington Floating Bridge", the original bridge included a movable span that could be retracted into a pocket in the center of the fixed span to permit large boats to pass. This design resulted in a roadway "bulge" that required vehicles to swerve twice across polished steel joints as they passed the bulge. A "reversible lane" system, indicated by lighted overhead lane control signals with arrow and 'X' signs, compounded the hazard by putting one lane of traffic on the "wrong" side of the bulge at different times of day in an effort to alleviate rush-hour traffic into or out of Seattle. There were many serious collisions on the bridge. The problems grew worse as the traffic load increased over the years and far outstripped the designed capacity. Renovation or replacement were essential and a parallel bridge, the Homer M. Hadley Memorial Bridge, was completed in 1989. Typical striping on an old-style suicide lane setup in the United States. ... Traffic lights can have several additional lights for filter turns or bus lanes. ... Homer M. Hadley Memorial Bridge (left), looking east toward Mercer Island The Third Lake Washington Bridge, officially the Homer M. Hadley Memorial Bridge, is the fifth longest floating bridge in the world, at 5,811 feet (1772 m). ... 1989 is a common year starting on Sunday of the Gregorian calendar. ...

The sinking of the original bridge was an example of human errors and decisions compounding to lead to disaster. The process started because the bridge needed resurfacing and was to be widened by means of cantilevered additions. The Washington State Department of Transportation decided to use hydrodemolition (high-pressure water) to remove unwanted material. Water from this hydrodemolition was considered contaminated under environmental law and could not be allowed to flow into Lake Washington. Engineers then analyzed the pontoons of the bridge, and realized that they were over-engineered and the water could be stored temporarily in the pontoons. The watertight doors for the pontoons were therefore removed. A large storm arose on November 22, 23, and 24, 1990 (the Thanksgiving holiday weekend). This filled some of the pontoons with rain and lake water. On November 24, workers noticed that the bridge was about to sink, and started pumping out some of the pontoons. However, on November 25, 850 meters of the bridge sank, ironically dumping the contaminated water into the lake along with tons of bridge material. The bridge sank when one pontoon filled and dragged the rest down because they were cabled together and there was no way to separate the sections under load. Fortunately, no one was hurt or killed, since the bridge was closed for renovation and the sinking took some time. All of the sinking was captured on film and shown on live TV. The Washington State Department of Transportation, or WSDOT, led by a Secretary and overseen by the Washington State Transportation Commission, is a Washington governmental agency that constructs, maintains, and regulates the use of the states transportation infrastructure. ... Water (from the Old English word wæter) is a colourless, tasteless, and odourless substance that is essential to all known forms of life and is known also as the most universal solvent. ... Environmental law is a body of law which addresses the system of complex and interlocking rules which seeks to protect from destruction or development the natural environment which may be endangered by human encroachment. ... A pontoon boat, like this small pleasure boat, typically floats and balances by means of two pontoons oriented in the direction of travel. ... November 22 is the 326th day (327th on leap years) of the year in the Gregorian calendar. ... November 23 is the 327th day of the year (328th in leap years) in the Gregorian Calendar, with 38 days remaining. ... November 24 is the 328th day (329th on leap years) of the year in the Gregorian Calendar. ... The First Thanksgiving, after the painting by Jean Louis Gerome Ferris (1863-1930) Thanksgiving is a holiday celebrated in much of North America, generally observed as an expression of gratitude, usually to God. ... Rain is a form of precipitation, other forms of which include snow, sleet, hail, and dew. ... November 25 is the 329th (in leap years the 330th) day of the year in the Gregorian calendar. ... An American family watching television in the 1950s. ...

See also

• Homer M. Hadley Memorial Bridge

Homer M. Hadley Memorial Bridge (left), looking east toward Mercer Island The Third Lake Washington Bridge, officially the Homer M. Hadley Memorial Bridge, is the fifth longest floating bridge in the world, at 5,811 feet (1772 m). ...

External links

• Bridge Camera, includes some weather information (http://traffic.wsdot.wa.gov/i90/bridge/I-90.htm)
• Report from engineering firm analyzing the sinking of the bridge (http://www.pubs.asce.org/WWWdisplay.cgi?9500186)
• History Link on the Bridge (http://www.historylink.org/_output.cfm?file_id=2002)
• Department of Transportation Sinking photos (http://www.wsdot.wa.gov/projects/SR520Bridge/sinkingbridges.htm)