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Main Street Bridge (Hillsboro, Oregon)
Encyclopedia
Main Street Bridge is a tied concrete arch bridge located in Hillsboro, Oregon
, United States
. The bridge carries light rail
traffic over Main Street and 18th Street on TriMet
’s MAX Blue Line
that runs from Gresham
to Hillsboro. Completed in 1997, the 425 feet (130 m) long bridge was built with a 78 feet (24 m) tall arch in the center. It is located between the 12th Avenue Station
and the Fair Complex Station
.
structure with the center pier
as an arch support straddling the road. Used in lieu of a center support, the arch is 110 feet (34 m) wide and 75 feet (23 m) tall. Six cables measuring four inches (102 mm) in diameter run from the arch to the main structure of the bridge at the center. The two ends of the reinforced concrete
arch are connected to each other underground using a post-tension tie beam, making the structure a tied arch.
, built in 1917. After abandonment of freight service on the line in the mid-1970s, the city required the successor railroad Burlington Northern to remove the old crossing, in 1977. In September 1997, the construction of the bridge structure was completed. The “golden spike” of the Westside light rail line was driven with the final pieces of track of the project installed on this bridge in October 1997. Passenger service on the $964 million project began on September 12, 1998.
Hillsboro, Oregon
Hillsboro is the fifth-largest city in the U.S. state of Oregon and is the county seat of Washington County. Lying in the Tualatin Valley on the west side of the Portland metropolitan area, the city is home to many high-technology companies, such as Intel, that compose what has become known as the...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. The bridge carries light rail
Light rail
Light rail or light rail transit is a form of urban rail public transportation that generally has a lower capacity and lower speed than heavy rail and metro systems, but higher capacity and higher speed than traditional street-running tram systems...
traffic over Main Street and 18th Street on TriMet
TriMet
TriMet, more formally known as the Tri-County Metropolitan Transportation District of Oregon, is a public agency that operates mass transit in a region that spans most of the Portland metropolitan area in the U.S. state of Oregon...
’s MAX Blue Line
MAX Blue Line
The MAX Blue Line is a 33 mile light rail line in the MAX Light Rail system in the Portland metropolitan area in the U.S. state of Oregon. Operated by TriMet, the line runs between Hillsboro and Gresham, via downtown Portland...
that runs from Gresham
Gresham, Oregon
- Demographics :As of the census of 2000, there were 90,205 people, 33,327 households, and 22,695 families residing in the city. The population density was 4,071.6 people per square mile . There were 35,309 housing units at an average density of 1,593.8 per square mile...
to Hillsboro. Completed in 1997, the 425 feet (130 m) long bridge was built with a 78 feet (24 m) tall arch in the center. It is located between the 12th Avenue Station
Washington/Southeast 12th Avenue (MAX station)
The Washington/Southeast 12th Avenue station is a light rail station on the MAX Blue Line in Hillsboro, Oregon. Hillsboro's West Precinct is near the station...
and the Fair Complex Station
Fair Complex/Hillsboro Airport (MAX station)
The Fair Complex/Hillsboro Airport station is a light rail station on the MAX Blue Line in Hillsboro, Oregon, United States. It is the 16th stop westbound on the Westside MAX, and the last westbound stop prior to crossing the Main Street Bridge...
.
Design
The bridge is a post-tension box girderBox girder
A box or tubular girder is a girder that forms an enclosed tube with multiple walls, rather than an or H-beam. Originally constructed of riveted wrought iron, they are now found in rolled or welded steel, aluminium extrusions or pre-stressed concrete....
structure with the center pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...
as an arch support straddling the road. Used in lieu of a center support, the arch is 110 feet (34 m) wide and 75 feet (23 m) tall. Six cables measuring four inches (102 mm) in diameter run from the arch to the main structure of the bridge at the center. The two ends of the reinforced concrete
Reinforced concrete
Reinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...
arch are connected to each other underground using a post-tension tie beam, making the structure a tied arch.
History
After more than a decade of studies and designing, construction on the Westside MAX light rail line began in 1993. In 1997, construction on the Main Street Bridge began. The bridge was designed by BRW to cross what is planned to be five lanes of traffic on Main Street. The city of Hillsboro required the bridge to be able to cross over the planned widening of the roadway without using a center support column, so as to prevent the kind of accidents that had plagued a previous crossing at the same location, a wooden trestle bridge of the Oregon Electric RailwayOregon Electric Railway
The Oregon Electric Railway was an interurban railroad line in the U.S. state of Oregon that linked Portland to Eugene. Service from Portland to Salem, Oregon, began in 1907. The Spokane, Portland and Seattle Railway purchased the system in 1910, and extended service to Eugene in 1912...
, built in 1917. After abandonment of freight service on the line in the mid-1970s, the city required the successor railroad Burlington Northern to remove the old crossing, in 1977. In September 1997, the construction of the bridge structure was completed. The “golden spike” of the Westside light rail line was driven with the final pieces of track of the project installed on this bridge in October 1997. Passenger service on the $964 million project began on September 12, 1998.
External links
- Benjamin, Adam J. Portland MAX: East-West MAX (Blue). world.nycsubway.org