First Avenue South Bridge
Encyclopedia
The First Avenue South Bridge is a pair of double-leaf bascule
bridge
s built between 1956 and 1998 that carry State Route 99
over the Duwamish River
about three miles (5 km) south of downtown Seattle
, Washington.
The northbound span was built in 1956 to connect the industrial areas northeast of the Duwamish to the residential neighborhoods to the south and southwest. Between 1996 and 1998, the drawspan was retrofitted and the approaches completely demolished and rebuilt. The southbound span opened in 1996 and carried traffic in both directions for two years while the northbound span was rebuilt.
In 2001, the southbound span was damaged by the Nisqually earthquake
, knocking its piers 3 inches out of alignment, and was closed briefly for repairs.
From the original construction to February 1995 when the retrofit began, the First Ave S bridge had the highest motor vehicle accident
rate in Washington State.
Bascule bridge
A bascule bridge is a moveable bridge with a counterweight that continuously balances the span, or "leaf," throughout the entire upward swing in providing clearance for boat traffic....
bridge
Bridge
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
s built between 1956 and 1998 that carry State Route 99
Washington State Route 99
State Route 99, abbreviated SR 99, commonly called Highway 99, is a numbered state highway in the U.S. state of Washington extending just under from Fife in the south to Everett in the north, with a gap in Tukwila.-Southern division:...
over the Duwamish River
Duwamish River
The Duwamish River is the name of the lower of Washington state's Green River. Its industrialized estuary is known as the Duwamish Waterway.- History :...
about three miles (5 km) south of downtown Seattle
Seattle, Washington
Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...
, Washington.
The northbound span was built in 1956 to connect the industrial areas northeast of the Duwamish to the residential neighborhoods to the south and southwest. Between 1996 and 1998, the drawspan was retrofitted and the approaches completely demolished and rebuilt. The southbound span opened in 1996 and carried traffic in both directions for two years while the northbound span was rebuilt.
In 2001, the southbound span was damaged by the Nisqually earthquake
Nisqually earthquake
The Nisqually earthquake was an intraslab earthquake, occurring at 10:54 a.m. PST . on February 28, 2001, and was one of the largest recorded earthquakes in Washington state history. The quake measured 6.8 on the MMS and lasted approximately 45 seconds. The epicenter of the earthquake was Anderson...
, knocking its piers 3 inches out of alignment, and was closed briefly for repairs.
From the original construction to February 1995 when the retrofit began, the First Ave S bridge had the highest motor vehicle accident
Car accident
A traffic collision, also known as a traffic accident, motor vehicle collision, motor vehicle accident, car accident, automobile accident, Road Traffic Collision or car crash, occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction,...
rate in Washington State.