Abernethy Bridge
Encyclopedia
The Abernethy Bridge is a steel plate and box girder bridge
that spans the Willamette River
between Oregon City
and West Linn, Oregon
, USA. It is also known as the Oregon City Freeway Bridge and the I-205 Bridge as it carries Interstate 205
.
The bridge was opened on May 3, 1970 at a cost of $15.9 million. An $8 million seismic retrofit
began in 1999 and was completed in 2002.
The bridge structure contains 15 spans and 60 girders. The total length is 2,727 ft (831 m) and the vertical clearance at low river levels is 85 ft (26 m). The longest span is 430 ft (131m) and is sandwiched by two 300 ft (91 m) spans. The bridge carries six lanes of traffic (3 in each direction—two through lanes, and one merging lane). Interchanges are located at each end of the bridge—on the western end (in West Linn) is an interchange with Oregon Route 43; on the eastern end (in Oregon City) is an interchange with OR 99E. The bridge is somewhat unusual in that its western approach is located on a bluff overlooking the river, whereas the eastern end is located in a lowland just south of the confluence of the Willamette and Clackamas
rivers; as a result, westbound traffic on I-205 travels uphill the entire length of the bridge, and continues uphill for another half-mile before the freeway summits and heads back downhill, into the lower Tualatin River
basin.
The bridge was named for George Abernethy
who was the governor of the Provisional Government of Oregon
and later an Oregon City businessman. In 2008 the average traffic was 95,500 vehicles per day.
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...
that spans the Willamette River
Willamette River
The Willamette River is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is long, lying entirely in northwestern Oregon in the United States...
between Oregon City
Oregon City, Oregon
Oregon City was the first city in the United States west of the Rocky Mountains to be incorporated. It is the county seat of Clackamas County, Oregon...
and West Linn, Oregon
West Linn, Oregon
West Linn is a city in Clackamas County, Oregon, United States. Now a prosperous southern suburb of Portland, West Linn has a history of early development, prompted by the opportunity to harvest energy from nearby Willamette Falls. It was named after Senator Dr. Lewis Fields Linn of Ste...
, USA. It is also known as the Oregon City Freeway Bridge and the I-205 Bridge as it carries Interstate 205
Interstate 205 (Oregon-Washington)
Interstate 205 is a loop route that serves the Portland—Vancouver metropolitan area in the U.S. states of Oregon and Washington. I-205 is officially named the War Veterans Memorial Freeway, and is also known as the East Portland Freeway...
.
The bridge was opened on May 3, 1970 at a cost of $15.9 million. An $8 million seismic retrofit
Seismic retrofit
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers,...
began in 1999 and was completed in 2002.
The bridge structure contains 15 spans and 60 girders. The total length is 2,727 ft (831 m) and the vertical clearance at low river levels is 85 ft (26 m). The longest span is 430 ft (131m) and is sandwiched by two 300 ft (91 m) spans. The bridge carries six lanes of traffic (3 in each direction—two through lanes, and one merging lane). Interchanges are located at each end of the bridge—on the western end (in West Linn) is an interchange with Oregon Route 43; on the eastern end (in Oregon City) is an interchange with OR 99E. The bridge is somewhat unusual in that its western approach is located on a bluff overlooking the river, whereas the eastern end is located in a lowland just south of the confluence of the Willamette and Clackamas
Clackamas River
The Clackamas River is an approximately tributary of the Willamette River in northwestern Oregon, in the United States. As it drains an area of about , the Clackamas passes through mostly forested and rugged mountainous terrain in its upper reaches, and passes through agricultural and urban areas...
rivers; as a result, westbound traffic on I-205 travels uphill the entire length of the bridge, and continues uphill for another half-mile before the freeway summits and heads back downhill, into the lower Tualatin River
Tualatin River
The Tualatin River is a tributary of the Willamette River located in Oregon in the United States. The river is approximately long, and it drains a fertile farming region called the Tualatin Valley southwest and west of Portland at the northwest corner of the Willamette Valley...
basin.
The bridge was named for George Abernethy
George Abernethy
George Abernethy was an American pioneer, notable entrepreneur, and first governor of Oregon under the provisional government in what would become the state of Oregon in the United States...
who was the governor of the Provisional Government of Oregon
Provisional Government of Oregon
The Provisional Government of Oregon was a popularly elected government created in the Oregon Country, in the Pacific Northwest region of North America. It existed from May 2, 1843 until March 3, 1849. Created at a time when no country had sovereignty over the region, this independent government...
and later an Oregon City businessman. In 2008 the average traffic was 95,500 vehicles per day.