The Hillsboro Main Street Bridge is a concrete

tied arch bridge A tied-arch bridge is an arch bridge in which the outward-directed horizontal forces of the arch(es) are borne as tension by a chord tying the arch ends rather than by the ground or the bridge foundations. This strengthened chord may be the deck ...

located in

Hillsboro, Oregon Hillsboro ( ) is a city in the U.S. state of Oregon and is the county seat of Washington County, Oregon, Washington County. Situated in the Tualatin Valley on the west side of the Portland metropolitan area, the city hosts many High tech, high-te ...

. The bridge carries

light rail Light rail (or light rail transit, abbreviated to LRT) is a form of passenger urban rail transit that uses rolling stock derived from tram technology National Conference of the Transportation Research Board while also having some features from ...

traffic on the

MAX Blue Line The MAX Blue Line is a light rail line serving the Portland metropolitan area in the U.S. state of Oregon. Operated by TriMet as part of MAX Light Rail, it connects Hillsboro, Oregon, Hillsboro, Beaverton, Oregon, Beaverton, Portland, and Gres ...

over Main Street and 18th Street. Completed in 1997, the bridge was built with a arch in the center. It is located between Washington/Southeast 12th Avenue station and the

Hillsboro Airport/Fairgrounds station Hillsboro Airport/Fairgrounds, formerly Fair Complex/Hillsboro Airport, is a light rail station on the MAX Blue Line, MAX Blue and MAX Red Line, Red lines in Hillsboro, Oregon, United States. It is the 16th stop westbound on the Westside MAX, an ...

Design

The bridge is a post-tension

box girder A box girder or tubular girder (or box beam) is a girder that forms an enclosed tube with multiple walls, as opposed to an i-beam, - or H-beam. Originally constructed of wrought iron joined by riveting, they are now made of rolled steel, rolled ...

structure with the center

pier A pier is a raised structure that rises above a body of water and usually juts out from its shore, typically supported by piling, piles or column, pillars, and provides above-water access to offshore areas. Frequent pier uses include fishing, b ...

as an arch support straddling the road.Cortright, Robert. 2003. ''Bridging the World''. Wilsonville, Or: Bridge Ink. Used in lieu of a center support, the arch is wide and tall.Arch support for Tri-Met extension; engineers in Hillsboro, Oregon, constructed a concrete arch over a roadway without using a center support, so that the arch can support bridge cables for the light rail overpass; Transit Update. ''

Railway Age ''Railway Age'' is an American trade magazine for the rail transport industry. It was founded in 1856 in Chicago (the United States' major railroad hub) and is published monthly by Simmons-Boardman Publishing Corporation. History The magazine ...

'', November 1997 No. 11, Vol. 198; Pg. 27; 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, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ...

arch are connected to each other underground using a post-tension tie beam, making the structure a

tied arch A tied-arch bridge is an arch bridge in which the outward-directed horizontal forces of the arch(es) are borne as tension by a chord tying the arch ends rather than by the ground or the bridge foundations. This strengthened chord may be the deck ...

History

After more than a decade of studies and designing, construction on the Westside MAX light rail line began in 1993.Westside light rail the MAX Blue Line extension.
TriMet. Retrieved on October 8, 2007. 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 A trestle bridge is a bridge composed of a number of short spans supported by closely spaced frames usually carrying a railroad line. A trestle (sometimes tressel) is a rigid frame used as a support, historically a tripod used to support a st ...

of the

Oregon Electric Railway The Oregon Electric Railway (OE) was an interurban streetcar, interurban railroad line in the U.S. state of Oregon that linked Portland, Oregon, Portland to Eugene, Oregon, Eugene. History Service from Portland to Salem, Oregon, Salem began in ...

, built in 1917 with a vehicle clearance height of just 10 feet, 6 inches.Boatwright, JoAnn (September 15, 1998). "Bridge new ‘gateway to city’". ''

The Hillsboro Argus ''The Hillsboro Argus'' was a twice-weekly newspaper in the city of Hillsboro, Oregon, from 1894 to 2017, known as the ''Washington County Argus'' for its final year. The ''Argus'' was distributed in Washington County, Oregon, United States. First ...

'', p. 8A. After abandonment of freight service on the line in the mid-1970s, the city required the successor railroad, the

Burlington Northern Railroad The Burlington Northern Railroad was a United States–based railroad company formed from a merger of four major U.S. railroads. Burlington Northern operated between 1970 and 1995. Its historical lineage begins in the earliest days of railroad ...

, to remove the old crossing, in 1977. In September 1997, the construction of the current bridge structure was completed.Oliver, Gordon and Don Hamilton (August 29, 1997). "MAX moves west: New rail stations will go on-line". ''

The Oregonian ''The Oregonian'' is a daily newspaper based in Portland, Oregon, United States, owned by Advance Publications. It is the oldest continuously published newspaper on the West Coast of the United States, U.S. West Coast, founded as a weekly by Tho ...

'', p. A1. 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.Oliver, Gordon and Don Hamilton (September 9, 1998). "Go west, young MAX". ''

''. Passenger service on the $964 million project began on September 12, 1998.

References

External links

* {{Hillsboro Oregon Bridges completed in 1997 Buildings and structures in Hillsboro, Oregon MAX Blue Line Concrete bridges in Oregon Tied arch bridges in the United States Railroad bridges in Oregon 1997 establishments in Oregon Transportation in Hillsboro, Oregon Box girder bridges in the United States Bridges in Washington County, Oregon