Aerial Lift Bridge
Encyclopedia
The Aerial Lift Bridge is a major landmark in the port city of Duluth, Minnesota
. The span is a vertical lift bridge
, which is rather uncommon, but it began life as an extremely rare transporter bridge
—the first of just two such bridges ever constructed in the United States
. Originally built in 1905, the bridge was upgraded in 1929–30 to the current lifting design and continues to operate today. The bridge was added to the National Register of Historic Places
on May 22, 1973. A maritime museum maintained by the United States Army Corps of Engineers exists near the site of the bridge.
which was put through the thin but long sand spit named Minnesota Point
(commonly referred to as Park Point by locals) in 1870–71. The natural mouth of the St. Louis River is about seven miles (11 km) farther southeast, and is split between Minnesota
and Wisconsin
. Creating this gap in the tiny peninsula
meant that residents who lived on the new island
needed to have a way to get across. Several different transportation methods were tried, though they were complicated by the weather. Ferries
could work in the summer, but ice caused problems in colder months. A swinging footbridge
was used, but was considered rather rickety and unsafe.
In 1892, a contest was held to find a solution. The winning design came from John Alexander Low Waddell
, who drew up plans for a high-rise vertical lift bridge. The city of Duluth was eager to build the bridge, which would have been about 130 feet (40 m) wide. However, the War Department
objected to the design, and the project was canceled before it could be built. Waddell's design went on to be built in Chicago, Illinois as the slightly larger South Halsted Street Bridge (removed in 1932).
New plans were later drawn up for a structure that would ferry people from one side to the other. This type of span, which is known variously as an aerial transfer, ferry, or transporter bridge, had first been demonstrated in Bilbao
's Vizcaya Bridge in 1893 and one in France
in 1898. Duluth's bridge was inspired by the one in France, though the actual construction is quite different. The architect
was a city engineer, Thomas McGilvray.
When it was completed in 1905, the Aerial Bridge's gondola had a capacity of 60 short ton
s (54 tonne
) and could carry 350 people plus wagon
s, streetcars, or automobile
s. A trip across the canal took about one minute, and the ferry car moved across once every five minutes during busy times of the day. However, a growing population on Minnesota Point, a greater demand for cars, and an increase in tourism
soon meant that the bridge's capacity was being stretched to the limit.
A remodeling was planned that would remove the gondola and incorporate a lifting platform into the structure. Ironically, the firm finally commissioned with designing the new bridge was the descendant of Waddell's company. The new design, which closely resembles the 1892 concept, is attributed to C.A.P. Turner
. Reconstruction began in 1929. In order to ensure that tall ships could still pass under the bridge, the top span had to be raised to accommodate the new deck when raised. The support columns on either side were also modified so that they could hold new counterweight
s to balance the weight of the lifting portion. The new bridge first lifted for a vessel on March 29, 1930.
The bridge can be raised to its full height in about 3 minutes, and goes up 25 to 30 times daily during busy parts of the shipping season. The span is about 390 feet, or 120 meters. As ships pass, there is a customary horn-blowing sequence which is copied back. Long-short-long-short means to raise the bridge, and Long-short-short is a friendly salute.
. The city of Superior even went to federal court
to halt the construction. An injunction
to stop work sat waiting to be served one weekend in 1871, so an army of 50 volunteers was quickly dispatched by Duluth's administrators to the canal site so it could be completed before Monday rolled around. They succeeded in creating a 30 foot (9 m) wide channel, essentially making the injunction meaningless.
In 1888 Wilhelm Boeing, who owned 14 plots on either side of the canal, tried to stake a claim that he had the right to charge a toll to ships using the canal. In October 1889, he posted notices around the Twin Ports that a rope would be stretched across the canal and that all canal traffic would be stopped. It is unclear on whether he ever carried out his threat, however, the issue became moot when he died the following month in Detroit. His son, William E. Boeing, went on to found the Boeing
aircraft
company.
Duluth, Minnesota
Duluth is a port city in the U.S. state of Minnesota and is the county seat of Saint Louis County. The fourth largest city in Minnesota, Duluth had a total population of 86,265 in the 2010 census. Duluth is also the second largest city that is located on Lake Superior after Thunder Bay, Ontario,...
. The span is a vertical lift bridge
Lift bridge
A vertical-lift bridge or lift bridge is a type of movable bridge in which a span rises vertically while remaining parallel with the deck....
, which is rather uncommon, but it began life as an extremely rare transporter bridge
Transporter bridge
A transporter bridge is a type of movable bridge that carries a segment of roadway across a river. The gondola is slung from a tall span by wires or a metal frame. The design has been used to cross navigable rivers or other bodies of water, where there is a requirement for ship traffic to be...
—the first of just two such bridges ever constructed in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Originally built in 1905, the bridge was upgraded in 1929–30 to the current lifting design and continues to operate today. The bridge was added to the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on May 22, 1973. A maritime museum maintained by the United States Army Corps of Engineers exists near the site of the bridge.
Bridge history
The bridge spans a small canalCanal
Canals are man-made channels for water. There are two types of canal:#Waterways: navigable transportation canals used for carrying ships and boats shipping goods and conveying people, further subdivided into two kinds:...
which was put through the thin but long sand spit named Minnesota Point
Minnesota Point
Minnesota Point, also known as the Park Point neighborhood of Duluth, Minnesota, United States; is a long, narrow sand spit that extends out from the Canal Park tourist recreation-oriented district of the city of Duluth...
(commonly referred to as Park Point by locals) in 1870–71. The natural mouth of the St. Louis River is about seven miles (11 km) farther southeast, and is split between Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
and Wisconsin
Wisconsin
Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...
. Creating this gap in the tiny peninsula
Peninsula
A peninsula is a piece of land that is bordered by water on three sides but connected to mainland. In many Germanic and Celtic languages and also in Baltic, Slavic and Hungarian, peninsulas are called "half-islands"....
meant that residents who lived on the new island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...
needed to have a way to get across. Several different transportation methods were tried, though they were complicated by the weather. Ferries
Ferry
A ferry is a form of transportation, usually a boat, but sometimes a ship, used to carry primarily passengers, and sometimes vehicles and cargo as well, across a body of water. Most ferries operate on regular, frequent, return services...
could work in the summer, but ice caused problems in colder months. A swinging footbridge
Footbridge
A footbridge or pedestrian bridge is a bridge designed for pedestrians and in some cases cyclists, animal traffic and horse riders, rather than vehicular traffic. Footbridges complement the landscape and can be used decoratively to visually link two distinct areas or to signal a transaction...
was used, but was considered rather rickety and unsafe.
In 1892, a contest was held to find a solution. The winning design came from John Alexander Low Waddell
John Alexander Low Waddell
John Alexander Low Waddell was an American civil engineer and prolific bridge designer, with more than a thousand structures to his credit in the United States, Canada, as well as Mexico, Russia, China, Japan, and New Zealand...
, who drew up plans for a high-rise vertical lift bridge. The city of Duluth was eager to build the bridge, which would have been about 130 feet (40 m) wide. However, the War Department
United States Department of War
The United States Department of War, also called the War Department , was the United States Cabinet department originally responsible for the operation and maintenance of the United States Army...
objected to the design, and the project was canceled before it could be built. Waddell's design went on to be built in Chicago, Illinois as the slightly larger South Halsted Street Bridge (removed in 1932).
New plans were later drawn up for a structure that would ferry people from one side to the other. This type of span, which is known variously as an aerial transfer, ferry, or transporter bridge, had first been demonstrated in Bilbao
Bilbao
Bilbao ) is a Spanish municipality, capital of the province of Biscay, in the autonomous community of the Basque Country. With a population of 353,187 , it is the largest city of its autonomous community and the tenth largest in Spain...
's Vizcaya Bridge in 1893 and one in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
in 1898. Duluth's bridge was inspired by the one in France, though the actual construction is quite different. The architect
Architect
An architect is a person trained in the planning, design and oversight of the construction of buildings. To practice architecture means to offer or render services in connection with the design and construction of a building, or group of buildings and the space within the site surrounding the...
was a city engineer, Thomas McGilvray.
When it was completed in 1905, the Aerial Bridge's gondola had a capacity of 60 short 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...
s (54 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
) and could carry 350 people plus wagon
Wagon
A wagon is a heavy four-wheeled vehicle pulled by draught animals; it was formerly often called a wain, and if low and sideless may be called a dray, trolley or float....
s, streetcars, or automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s. A trip across the canal took about one minute, and the ferry car moved across once every five minutes during busy times of the day. However, a growing population on Minnesota Point, a greater demand for cars, and an increase in tourism
Tourism
Tourism is travel for recreational, leisure or business purposes. The World Tourism Organization defines tourists as people "traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes".Tourism has become a...
soon meant that the bridge's capacity was being stretched to the limit.
A remodeling was planned that would remove the gondola and incorporate a lifting platform into the structure. Ironically, the firm finally commissioned with designing the new bridge was the descendant of Waddell's company. The new design, which closely resembles the 1892 concept, is attributed to C.A.P. Turner
C.A.P. Turner
Claude Allen Porter Turner was an American structural engineer who designed a number of buildings and bridges, particularly in the midwestern U.S. states of Iowa, Minnesota, and Wisconsin....
. Reconstruction began in 1929. In order to ensure that tall ships could still pass under the bridge, the top span had to be raised to accommodate the new deck when raised. The support columns on either side were also modified so that they could hold new counterweight
Counterweight
A counterweight is an equivalent counterbalancing weight that balances a load.-Uses:A counterweight is often used in traction lifts , cranes and funfair rides...
s to balance the weight of the lifting portion. The new bridge first lifted for a vessel on March 29, 1930.
The bridge can be raised to its full height in about 3 minutes, and goes up 25 to 30 times daily during busy parts of the shipping season. The span is about 390 feet, or 120 meters. As ships pass, there is a customary horn-blowing sequence which is copied back. Long-short-long-short means to raise the bridge, and Long-short-short is a friendly salute.
Duluth Ship Canal history
The canal that runs under the bridge has quite a story of its own. Construction began in 1870, but became a contentious issue with the neighboring port of Superior, WisconsinSuperior, Wisconsin
Superior is a city in and the county seat of Douglas County, Wisconsin, United States. The population was 26,960 at the 2010 census. Located at the junction of U.S. Highways 2 and 53, it is north of and adjacent to both the Village of Superior and the Town of Superior.Superior is at the western...
. The city of Superior even went to federal court
Court
A court is a form of tribunal, often a governmental institution, with the authority to adjudicate legal disputes between parties and carry out the administration of justice in civil, criminal, and administrative matters in accordance with the rule of law...
to halt the construction. An injunction
Injunction
An injunction is an equitable remedy in the form of a court order that requires a party to do or refrain from doing certain acts. A party that fails to comply with an injunction faces criminal or civil penalties and may have to pay damages or accept sanctions...
to stop work sat waiting to be served one weekend in 1871, so an army of 50 volunteers was quickly dispatched by Duluth's administrators to the canal site so it could be completed before Monday rolled around. They succeeded in creating a 30 foot (9 m) wide channel, essentially making the injunction meaningless.
In 1888 Wilhelm Boeing, who owned 14 plots on either side of the canal, tried to stake a claim that he had the right to charge a toll to ships using the canal. In October 1889, he posted notices around the Twin Ports that a rope would be stretched across the canal and that all canal traffic would be stopped. It is unclear on whether he ever carried out his threat, however, the issue became moot when he died the following month in Detroit. His son, William E. Boeing, went on to found the Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
company.
See also
- Transporter bridgeTransporter bridgeA transporter bridge is a type of movable bridge that carries a segment of roadway across a river. The gondola is slung from a tall span by wires or a metal frame. The design has been used to cross navigable rivers or other bodies of water, where there is a requirement for ship traffic to be...
– other similar bridges in the world. - John A. Blatnik BridgeJohn A. Blatnik BridgeThe John A. Blatnik Bridge is the bridge that carries Interstate Highway 535 and U.S. Highway 53 over the Saint Louis Bay, a tributary of Lake Superior, between Duluth, Minnesota and Superior, Wisconsin. The bridge is long and rises up nearly above the water to accommodate the seaway shipping...
– the nearby Interstate 535Interstate 535Interstate 535 is a long Interstate Highway spur route of Interstate 35 in Minnesota and Wisconsin, in the United States. It is paired with U.S...
crossing in Duluth-Superior - Richard I. Bong Memorial BridgeRichard I. Bong Memorial BridgeThe Richard I. Bong Memorial Bridge, also known as the Bong Bridge, connects Duluth, Minnesota with Superior, Wisconsin via U.S. Highway 2. Opened on October 25, 1985, it is roughly 11,800 feet long. About 8,300 feet of that length is actually over water. It crosses over the Saint Louis Bay...
– the nearby U.S. Route 2U.S. Route 2U.S. Route 2 is an east–west U.S. Highway spanning across the northern continental United States. US 2 consists of two segments connected by various roadways in southern Canada...
crossing - Sky RideSky RideThe Sky Ride was an attraction built for the Century of Progress Exposition in Chicago, Illinois in 1933. It was a transporter bridge , designed by the bridge engineering firm Robinson & Steinman, that ferried people across the lagoon in the center of the fair...
– the other ferry bridge built in the U.S., an exhibit at the 1933–34 World's Fair, "Century of ProgressCentury of ProgressA Century of Progress International Exposition was the name of a World's Fair held in Chicago from 1933 to 1934 to celebrate the city's centennial. The theme of the fair was technological innovation...
," in Chicago - South Halsted Street Bridge – Waddell's bridge design as built in Chicago
- Stillwater Bridge – another lift bridge in Minnesota (connecting to Wisconsin)
External links
- Architecture and History of the Duluth Aerial Lift Bridge
- Duluth Aerial Lift Bridge Library of Congress, Historical American Engineering Record, Survey number HAER MN-44
- James Baughn and contributors, Historic Bridges of the United States:Duluth Aerial Lift Bridge
- Bridge raising video