Lacey V. Murrow Memorial Bridge
47.58978355 - 122.26826191Koordinaten: 47 ° 35 ' 23.2 " N, 122 ° 16' 5.7 " W
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The Lacey V. Murrow Memorial Bridge, originally Lake Washington Floating Bridge and Mercer Iceland Bridge is a floating bridge in the U.S. state of Washington. It is used by the eastward leading carriageway of Interstate 90 to the crossing of Lake Washington between Seattle through Mercer Iceland, the carriageway for traffic to use the north -west parallel to the Lacey V. Murrow Memorial Bridge Homer M. Hadley running Memorial Bridge.
The Lacey V. Murrow Memorial Bridge is named for Lacey V. Murrow, former head of the Office of Road Washington and was with a length of 2019 meters at the opening of 1940, the longest floating bridge in the world. It was not surpassed until 1963 by a few kilometers north Situated 2310 meters long Governor Albert D. Rosellini Bridge - Evergreen Point.
Together with the eastern portals of the Mount Baker Ridge Tunnel is the Lacey V. Murrow Memorial Bridge an official monument of the city of Seattle and a national monument of the American Association of Civil Engineers ASCE.
History
Early 20th century has been looking for ways to improve the development of the east coast of Lake Washington from Seattle. The Lake Washington has an average depth of 30 m, which elaborately made a bridge with pillars to impossible. Engineer Homer Hadley, who was employed during the First World War with the construction of concrete ships, therefore, suggested the construction of a floating bridge. The authorities were skeptical about the idea and the construction of a privately funded toll bridge also did not seem to be possible because the banks were not receptive to the proposal and it was Hadley 's Folly, German " Hadley's Folly " referred to. Only George Lightfoot and the politically active publisher Miller Freeman, both residing in Mercer Iceland, supported the idea of a bridge to enhanced accessibility to home. During the Great Depression, as were state funds for execution of construction projects available, Hadley presented the proposal to the then director of the Washington State Highway Department Lacey V. Murrow, who was fascinated by the proposal and let him implement.
The bridge was henceforth referred to as the Lake Washington Floating Bridge. The design of reinforced concrete was developed by Hadley. It comprised a floating bridge in reinforced concrete dual carriageway and four lanes. The bridge was part of the Lake Washington Bridge Project, which included not only the floating bridge also the west adjoining twin-tube Mount Baker Ridge Tunnel and the East Channel Bridge, and U.S. Highway 10, which later became Interstate 90, according to Bellevue Mercer Iceland Seattle leads. The Lake Washington Floating Bridge consisted of 25 floating bridge with anchored in the lake bottom pontoons made of concrete and the two bridge spans designed as a tied arch bridges. These were mounted on both sides so that they could follow the movements of the floating bridge. The superstructure of the floating bridge was a box girder of reinforced concrete. On the east side a field of floating bridge was designed as a thrust bridge, whose moving part could be retracted into a pocket in the center of the adjacent fixed field to allow larger ships to pass through. The roadways were pivoted laterally guided around the pocket.
Construction began in December 1938, the opening took place on 2 July 1940. Until 1946, the bridge was a toll road. The bridge has already led to the beginning of much more traffic than expected. They contributed significantly to the fact that Mercer Iceland developed from a summer resort to a suburb of Seattle and the once predominantly agricultural Bellevue the fourth largest city in the state was.
In 1967, the bridge was renamed in honor of the recently deceased in Lacey in Lacey V. Murrow Memorial Bridge.
In 1981, the 60 m long bridge thrust contained in the building was expanded and replaces the array with the roads pivoted by a normal straight field. This could often leading to traffic accidents body that could only be driven at a reduced speed, be eliminated. The location was especially dangerous because depending on time of day, the direction of the middle two lanes was changed with variable message signs to increase the capacity in the main traffic direction. This caused the vehicle driver had to drive around to the left or right of the obstacle depending on the track selection. In addition, a metal joint was at a shallow angle over the roadways. Therefore, it was at this point that, German " bulge " was referred to as the bulge, again and again to serious accidents.
The traffic load had over the years the planned capacity far exceeded, so that the operation of the bridge was becoming increasingly difficult. A renovation was urgently needed. You could be addressed after the opening of the 1989 completed parallel to the existing bridge extending Homer M. Hadley Memorial Bridge. During this repair work, the Lacey V. Murrow Memorial Bridge sank on November 25, 1990 in a storm and had to be replaced by a new building which was completed in 1993. The Lacey V. Murrow Memorial Bridge now manages only traffic to the east, while traffic to the west, the Homer M. Hadley Memorial Bridge used.
Sinking of the bridge in 1990
The Lacey V. Murrow Memorial Bridge sank on November 25, 1990 due to a number of human errors and wrong decisions. The trigger was the intention to renew the road surface and to widen the bridge by attaching lateral cantilever beam, so that the width of the lanes would again meet the requirements of the Interstate Highway System. The Washington State Department of Transportation ( WSDOT ) decided to separate the unused components, such as the sidewalks on both sides of the roadway support by high-pressure water jets. The water used in this case was under environmental law as dirty and was not allowed to enter the Lake Washington.
Engineers analyzed the pontoons used in the original bridge construction of the bridge and found that they were oversized. It was therefore decided to store the contaminated water temporarily in the pontoons, so the watertight seal doors were removed to the cavity in the interior of the pontoons.
On Thanksgiving weekend 1990 ( November 22 to 24 ) penetrated during heavy storm rain and sea water in some of the no longer sealed pontoons. As a construction worker discovered the damage on November 24, they immediately began with the evacuation of the pontoons. Nevertheless, sank on 25 November, a 850 -meter-long section of the bridge with the mounted therein dirty water and several tons of building material in the lake. After one of the pontoons had filled with water, were gradually moved to more pontoons in depth in a chain reaction. The steel cables that connected the pontoons together, could not be resolved under load. Since the bridge was completely closed due to construction and slowly sank, no one was injured. The process was recorded by cameras and broadcast live on television. The damage amounted to 69 million dollars.
Ten years before the demise of the Lacey V. Murrow Memorial Bridge, the Hood Canal Bridge had fallen in similar circumstances. Meanwhile, also announced that the Governor Albert D. Rosellini Bridge - Evergreen Point is undersized for the local environmental conditions.