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40-571: The West Seattle Bridge , officially the Jeanette Williams Memorial Bridge , is a cantilevered segmental bridge that serves as the primary connection between West Seattle and important highways such as State Route 99 (and the tunnel through downtown ), the Spokane Street Viaduct , and Interstate 5 . It was built between 1981 and 1984 after the previous bascule bridge was deemed inoperable as

80-664: A cantilever bridge. The Forth Bridge is a notable example of an early cantilever bridge. This bridge held the record for longest span in the world for twenty-nine years until it was surpassed by the Quebec Bridge . The engineers responsible for the bridge, Sir Benjamin Baker and Sir John Fowler , demonstrated the structural principles of the suspended span cantilever by sitting in chairs and supporting their colleague, Kaichi Watanabe , in between them, using just their arms and wooden poles. The suspended span, where Watanabe sits,

120-410: A federal highway regulator, stated that there would essentially be no chance of the project receiving federal funds for completion. Tiemann also quipped, "Short of a tug knocking it down (which could trigger federal special bridge replacement funds), there is nothing else. And you certainly wouldn't want to go that route." In March 1978, several prominent West Seattle residents filed a petition to organize

160-507: A hinge in the girder. Heinrich Gerber was one of the engineers to obtain a patent for a hinged girder (1866) and is recognized as the first to build one. The Hassfurt Bridge over the Main river in Germany with a central span of 124 feet (38 metres) was completed in 1867 and is recognized as the first modern cantilever bridge. The High Bridge of Kentucky by C. Shaler Smith (1877),

200-504: A pin, usually after forcing the union point apart, and when jacks are removed and the bridge decking is added the bridge becomes a truss arch bridge . Such unsupported construction is only possible where appropriate rock is available to support the tension in the upper chord of the span during construction, usually limiting this method to the spanning of narrow canyons. World's longest cantilever bridges (by longest span): Forward Thrust The Forward Thrust ballot initiatives were

240-610: A resolution to lower the speed limit and to request that the WSDOT remove the word "Freeway" from signs marking the entrances to the Spokane Street Viaduct and the West Seattle Bridge. The West Seattle Bridge was renamed as the Jeanette Williams Memorial Bridge on July 6, 2009, in honor of councilmember Williams, who had been instrumental in securing political support for the construction of

280-530: A result of being struck by the freighter Antonio Chavez in 1978. The high-level bridge was closed in March 2020 after cracks in the underside were found to be growing rapidly, necessitating a major repair amid the COVID-19 pandemic . The Seattle Department of Transportation conducted repairs over a two-and-a-half-year period and reopened the bridge on September 17, 2022. Bicycles are usually not allowed on

320-402: A secession referendum, with the hopes of finding state funding for a new bridge to serve their independent city. The secession campaign was required to gather 29,000 signatures for a ballot measure, but were unable to meet the threshold before the northern or westbound drawbridge was permanently closed and all east–west traffic was funneled over the southern span. On June 11, 1978, a ship struck

360-553: A series of bond propositions put to the voters of King County , Washington in 1968 and 1970, designed by a group called the Forward Thrust Committee . Seven of the twelve propositions in 1968 were successful; four of the remaining propositions were repackaged for a vote in 1970, when they were defeated in the darkening local economic climate of the Boeing Bust. One of the most visible accomplishments of

400-486: A three-mile (5 km) arterial between West Seattle and Interstate 5 (which comprises a road formerly known as the " West Seattle Freeway "). The navigational clearance height of the high-level West Seattle Bridge is 140 feet (43 meters). The low-level Spokane Street Bridge of swing-span design spans the west channel of the Duwamish River immediately north of the high-level bridge. The low-level bridge carries

440-557: Is a concrete double-leaf swing bridge that was constructed traffic formerly carried by the West Spokane Street Bridge . It carries Southwest Spokane Street over the Duwamish River , connecting Harbor Island to West Seattle . It has two separate end-to-end swing-span sections, each 480 feet (150 m) long. Its construction was finished in 1991, replacing an earlier bridge destroyed by a collision . It

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480-505: Is formed by two cantilever arms extending from opposite sides of an obstacle to be crossed, meeting at the center. In a common variant, the suspended span , the cantilever arms do not meet in the center; instead, they support a central truss bridge which rests on the ends of the cantilever arms. The suspended span may be built off-site and lifted into place, or constructed in place using special travelling supports. A common way to construct steel truss and prestressed concrete cantilever spans

520-424: Is in the center. The wooden poles resist the compression of the lower chord , while the outstretched arms support the tension of the upper chord. The placement of the brick counterweights demonstrates the action of the outer foundations. Cantilever Bridge.—A structure at least one portion of which acts as an anchorage for sustaining another portion which extends beyond the supporting pier. A simple cantilever span

560-472: Is named after Spokane Street, which itself is named after Spokane, Washington , which is named after the Spokane people . Each 7,500-short-ton (6,800 t) leaf of the bridge floats on a 100-inch (2.5 m) steel barrel in hydraulic oil , situated in center piers at each side of the river. As the bridge intersects the river at an oblique angle, both leaves rotate only 45 degrees (one-eighth turn) to clear

600-405: Is to counterbalance each cantilever arm with another cantilever arm projecting the opposite direction, forming a balanced cantilever ; when they attach to a solid foundation, the counterbalancing arms are called anchor arms . Thus, in a bridge built on two foundation piers, there are four cantilever arms: two which span the obstacle, and two anchor arms that extend away from the obstacle. Because of

640-547: The Niagara Cantilever Bridge by Charles Conrad Schneider (1883) and the Poughkeepsie Bridge by John Francis O'Rourke and Pomeroy P. Dickinson (1889) were all important early uses of the cantilever design. The Kentucky River Bridge spanned a gorge that was 275 feet (84 metres) deep and took full advantage of the fact that falsework, or temporary support, is not needed for the main span of

680-434: The "mid-2022" reopening were incurred by a multi-month concrete workers strike. The bridge reopened to traffic on September 17, 2022, two months later than originally expected. The repaired structure is expected to have a 95 percent chance of lasting until 2060; a future replacement was studied as part of the repair program along with an option to immediately replace the damaged bridge. The Spokane Street Viaduct section

720-769: The 1970 defeats. It disbanded formally in 1974. Seattle Mayor Dorm Braman was also a strong backer of the 1968 initiatives. The US$ 118 million passed in 1968 in support of the Department of Parks and Recreation was, at the time, the largest parks and recreation bond issue ever passed in the United States. The failure of the rapid transit propositions meant that a nearly $ 900 million federal funding earmark that had been secured by U.S. Senator Warren Magnuson if local bonds passed went instead to fund Atlanta, Georgia 's MARTA . The elections took place February 13, 1968, and May 19, 1970. Each initiative required

760-625: The 1970s, the West Spokane Street Bridge was one of Seattle's worst bottlenecks, due to the large number of ships in Duwamish Waterway and the frequent bridge openings. City leaders began planning a higher bridge, without a drawbridge, in the 1960s. Planning for the bridge was hampered by difficulties in receiving funding. In large part, this is because the bridge was not a designated highway. A 1968 Forward Thrust ballot measure included $ 16.7 million in funding for

800-674: The Forward Thrust levy was the eventual building of the Kingdome, ultimately the first home of the Seattle Seahawks and Seattle Mariners. The initiatives were variously under the aegis of METRO (the Municipality of Metropolitan Seattle ), King County, and the city of Seattle. (METRO and King County merged in 1992.) The Forward Thrust Committee was founded by James R. Ellis and effectively disbanded shortly after

840-429: The bridge, largely to receive votes from West Seattle residents. Other funding sources included a state program for funding urban streets and money from a maintenance fund. After a long drawn-out process , three companies eventually bid to design the bridge for $ 1.5 million. However, the city engineer chose a fourth company that was financially connected to the speaker of the state house. The price from this fourth company

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880-487: The bridge. The bridge spans the east and west channels that form the mouth of the Duwamish River at Elliott Bay , crossing over Harbor Island . Its main approaches are Fauntleroy Way S.W. from the west and the Spokane Street Viaduct from the east. Drivers heading east over the West Seattle Bridge can continue (via the Spokane Street Viaduct) east to Interstate 5 at Columbian Way (exit 163), forming

920-606: The bridge. However, all directional signs continue to carry the name "West Seattle Bridge." From 2008 to 2013, the Spokane Street Viaduct section between Interstate 5 and State Route 99 was rebuilt and widened. The widened roadway has three lanes in each direction and shoulders. A new westbound on and off ramp was built at 1st Avenue South and replaced the dangerous 4th Avenue South off-ramp. A new eastbound off-ramp to 4th Avenue South opened August 16, 2010. Cantilever bridge The steel truss cantilever bridge

960-441: The construction of the bridge. All directional signs still carry the name "West Seattle Bridge", many of which had formerly borne the designation "West Seattle Freeway". The bridge caused an increase in property values as well as a development boom, as developers constructed new multi-family housing. This new development also led to an increase in traffic volumes throughout the neighborhood. A monorail extension to West Seattle in

1000-455: The council from 1970 to 1989, lobbied Congress for the bridge and successfully secured funds with help from Senator Warren Magnuson . The smaller Spokane Street Bridge which parallels it was built at the same time. The replacement bridge was opened in 1984. The West Seattle Bridge was renamed as the Jeanette Williams Memorial Bridge on July 6, 2009, in honor of councilmember Williams, who had been instrumental in securing political support for

1040-469: The deck were discovered during a routine inspection. The girder wall cracks had grown to 2 ft (0.61 m) within a month, while the hollow girder cracks had been noticed during inspections. An earlier report from 2014 speculated that earlier cracks had been caused by the 2001 Nisqually earthquake . On April 15, SDOT announced that the bridge will be closed until at least 2022 because of more extensive damage found and estimated time to complete bracing for

1080-436: The early 2000s was planned to use the West Seattle Bridge, with elevated columns over the center barrier. The plan was later scaled down to a single-track guideway over the bridge and abandoned entirely in 2005 over cost concerns. After completion of the high-level bridge, a lower bridge was needed to carry traffic between Harbor Island and West Seattle . The " Spokane Street Bridge " (or the " West Seattle Low-Level Bridge ")

1120-410: The girder or truss and meant that longer spans could be built. Several 19th-century engineers patented continuous bridges with hinge points mid-span. The use of a hinge in the multi-span system presented the advantages of a statically determinate system and of a bridge that could handle differential settlement of the foundations. Engineers could more easily calculate the forces and stresses with

1160-411: The need for more strength at the balanced cantilever's supports, the bridge superstructure often takes the form of towers above the foundation piers. The Commodore Barry Bridge is an example of this type of cantilever bridge. Steel truss cantilevers support loads by tension of the upper members and compression of the lower ones. Commonly, the structure distributes the tension via the anchor arms to

1200-411: The old bridge , which left it open and unrepairable. Because of this, the project qualified for funds from the federal Office of Special Bridge Replacement. However, with many other damaged bridges to replace, this program alone did not have sufficient funding. While federal lawmakers were opposed to appropriating funds to a high-level bridge, Seattle City Council member Jeanette Williams , who served on

1240-609: The outermost supports, while the compression is carried to the foundations beneath the central towers. Many truss cantilever bridges use pinned joints and are therefore statically determinate with no members carrying mixed loads. Prestressed concrete balanced cantilever bridges are often built using segmental construction . Some steel arch bridges (such as the Navajo Bridge ) are built using pure cantilever spans from each side, with neither falsework below nor temporary supporting towers and cables above. These are then joined with

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1280-489: The repair project. In November 2020, mayor Jenny Durkan announced that the city would focus on repairing the bridge for $ 47 million with a projected opening of 2022. An option to replace the damaged section with a new steel span would have been completed in 2025 or 2026 and cost $ 390 million to $ 522 million. Kraemer North America was selected as the main contractor for the bridge repair project in May 2021. Delays on

1320-568: The shipping channel instead of the 90-degree turn of most swing spans. It is claimed to be the only bridge of its type in the world and it has received several awards for its innovation, including the Outstanding Engineering Achievement Award of the American Society of Civil Engineers in 1992. On March 23, 2020, SDOT began a long-term closure of the bridge for emergency repairs after cracks in

1360-411: The surface-level Spokane Street and has a navigational clearance of 45 feet (14 meters). Spokane Street has long been used as designation for the streets running along the latitude of the current West Seattle Bridge. Construction on the " West Spokane Street Bridge " (a bascule drawbridge ) was completed in 1924, and the bridge lasted over fifty years. Then (in 1978) the portion of the bridge carrying

1400-460: The westbound lanes of the bridge was rammed by the Chavez. The bridge formerly carrying the eastbound lanes remained open until 1984, at which point the high-level bridge (the "West Seattle Bridge") was opened. The low-level bascule bridge remained open until 1991, when the " Spokane Street Bridge " (a swing bridge) was opened. The bridge that preceded the "West Seattle Bridge" as we know it today

1440-409: Was a major engineering breakthrough when first put into practice, as it can span distances of over 1,500 feet (450 m), and can be more easily constructed at difficult crossings by virtue of using little or no falsework . Engineers in the 19th century understood that a bridge that was continuous across multiple supports would distribute the loads among them. This would result in lower stresses in

1480-505: Was a swing bridge after the water main had been rerouted elsewhere. A more permanent bascule bridge was constructed in 1924, which lasted for several decades. In 1945, one of Seattle's oldest freeways (the "Spokane Street Viaduct") connected the bridge to Beacon Hill . Prior to the construction of Interstate 5 in Washington , the viaduct was separated from the bridge by the main north–south corridor: U.S. Route 99 in Washington . By

1520-401: Was called the "West Spokane Street Bridge". Before any permanent bridge was built along the line of Spokane Street, there had been three temporary bridges, built c.  1900 , c.  1910 , and c.  1918 . The first one was basically a swinging gate in what had been primarily built as a water main; the second was a swing bridge that also carried a water main, and the third

1560-495: Was one of Seattle's first freeways, built in 1945. Upon completion of the West Seattle Bridge in 1984, the road comprising the Spokane Street Viaduct and the West Seattle Bridge was referred to as the "West Seattle Freeway". However, a series of fatalities led to recognition that the aging Spokane Street Viaduct portion was unsafe to be used as a high-speed roadway. In 1997, the Seattle City Council unanimously adopted

1600-519: Was triple the cost of the other three. This was a result of a series of bribes involving the head of the House Transportation Committee, the city engineer and others. Despite the 68 percent support in the 1968 ballot measure, the state withdrew its urban streets money due to the scandal. In 1976 and 1977, the conspirators were placed on trial and imprisoned. After the scandal, the project was considered dead. Norbert Tiemann,

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