Morrison Bridge
Encyclopedia
The Morrison Bridge is a bascule bridge
that spans the Willamette River
in Portland, Oregon
.
The original Morrison Bridge was a wooden truss swing span bridge
completed on April 12, 1887 as the first Willamette River bridge in Portland and the longest bridge west of the Mississippi River
. It was first a toll bridge
(rates: horse drawn rig - US$0.15, team of horses - $0.20, pedestrian - $0.05) but went toll free in 1895. The second Morrison was another swing bridge that was built in 1905. It was not designed for automobiles and the 1958 replacement was long overdue.
The present bridge was built by Multnomah County
. It was completed on May 24, 1958 at a cost of $12.9 million. In 1961, Interstate 5 and Interstate 84
ramps were added. In 2011, the steel grating on the bascule deck was scheduled to be replaced with fiber-reinforced polymer panels to provide better traction for vehicles. However, due to environmental issues with the contractor, the work will not be completed until 2012. Access for bicycles and pedestrians is being improved in a $1.9 million project which began construction in March 2009. Multnomah County estimates a major seismic upgrade around 2020.
The bridge is the largest mechanical device in Oregon
. 36 ft. tall gears drive 940-ton
counterweights located inside each of the piers. The 69 ft. clearance is sufficient for most river traffic, requiring bridge openings only about 30 times a month. It currently carries 50,000 vehicles daily in six lanes. The canted windows of the control tower give the distinctive look of air traffic control
towers. It is named after John L. Morrison
, a Scottish
immigrant who built the first home on Morrison Street. The current bridge does not connect to Morrison Street at its west end because the second bridge was left in operation while the latest version was built.
In 1987 the Morrison Bridge became the first bridge illuminated by the Willamette Light Brigade. In 2007 the original 16 colored floodlamps illuminating the concrete piers were replaced by energy efficient and computer controlled LED
s.
Millions of colors may be selected for each of eight zones of the piers.
Static and animated patterns may be requested for a fee which ranges from $100 per night to $1200 per month.
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....
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...
in Portland, Oregon
Portland, Oregon
Portland is a city located in the Pacific Northwest, near the confluence of the Willamette and Columbia rivers in the U.S. state of Oregon. As of the 2010 Census, it had a population of 583,776, making it the 29th most populous city in the United States...
.
The original Morrison Bridge was a wooden truss swing span bridge
Swing bridge
A swing bridge is a movable bridge that has as its primary structural support a vertical locating pin and support ring, usually at or near to its centre of gravity, about which the turning span can then pivot horizontally as shown in the animated illustration to the right...
completed on April 12, 1887 as the first Willamette River bridge in Portland and the longest bridge west of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
. It was first a toll bridge
Toll bridge
A toll bridge is a bridge over which traffic may pass upon payment of a toll, or fee.- History :The practice of collecting tolls on bridges probably harks back to the days of ferry crossings where people paid a fee to be ferried across stretches of water. As boats became impractical to carry large...
(rates: horse drawn rig - US$0.15, team of horses - $0.20, pedestrian - $0.05) but went toll free in 1895. The second Morrison was another swing bridge that was built in 1905. It was not designed for automobiles and the 1958 replacement was long overdue.
The present bridge was built by Multnomah County
Multnomah County, Oregon
Multnomah County is one of 36 counties in the U.S. state of Oregon. Though smallest in area, it is the most populous as its county seat, Portland, is the state's largest city...
. It was completed on May 24, 1958 at a cost of $12.9 million. In 1961, Interstate 5 and Interstate 84
Interstate 84 in Oregon
In the U.S. state of Oregon, Interstate 84 travels east–west, following the Columbia River and the rough path of the old Oregon Trail from Portland east to Idaho. For this reason, it is also known as most of the Columbia River Highway No. 2 and all of the Old Oregon Trail Highway No. 6 . It...
ramps were added. In 2011, the steel grating on the bascule deck was scheduled to be replaced with fiber-reinforced polymer panels to provide better traction for vehicles. However, due to environmental issues with the contractor, the work will not be completed until 2012. Access for bicycles and pedestrians is being improved in a $1.9 million project which began construction in March 2009. Multnomah County estimates a major seismic upgrade around 2020.
The bridge is the largest mechanical device in Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. 36 ft. tall gears drive 940-ton
Ton
The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...
counterweights located inside each of the piers. The 69 ft. clearance is sufficient for most river traffic, requiring bridge openings only about 30 times a month. It currently carries 50,000 vehicles daily in six lanes. The canted windows of the control tower give the distinctive look of air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
towers. It is named after John L. Morrison
John L. Morrison (pioneer)
John L. Morrison arrived in Oregon Country in 1842 along with other famous Oregon pioneers Medorem Crawford, Asa Lovejoy, and Sidney Moss in the same wagon train. Morrison built the home of Francis Pettygrove in early Portland, Oregon. The street on which Pettygrove's house was located was named...
, a Scottish
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
immigrant who built the first home on Morrison Street. The current bridge does not connect to Morrison Street at its west end because the second bridge was left in operation while the latest version was built.
In 1987 the Morrison Bridge became the first bridge illuminated by the Willamette Light Brigade. In 2007 the original 16 colored floodlamps illuminating the concrete piers were replaced by energy efficient and computer controlled LED
Light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
s.
Millions of colors may be selected for each of eight zones of the piers.
Static and animated patterns may be requested for a fee which ranges from $100 per night to $1200 per month.