In the city of Duluth, Minnesota, a bridge has kept people safe for more than a century. It is the only lifting span bridge design of its kind in the world and a true masterpiece of engineering. The bridge has withstood fires, ice jams, and many other threats.
It's called the Duluth Aerial Lift Bridge and is one of the city's most recognizable landmarks.
The Duluth Aerial Lift Bridge
ThatDuluth airlift bridgewas built between 1901 and 1905. Boats can pass under the bridge and avoid boat traffic when entering Duluth-Superior Harbor. The bridge was designed so that the center section could be raised to allow tall ships to pass.
Today, the bridge is primarily used by pleasure boats, although it is still open to commercial traffic.
operated by abridge tender, the middle section will be lowered and raised according to a published timetable. The Duluth Aerial Lift Bridge is one of the city's most recognizable landmarks and continues to play an important role in the community.
The Duluth Lift Bridge is one of two remaining lift bridges in Minnesota. The other is the Saint Louis River Bridge, which crosses the St. Louis River near Cloquet, Minnesota.
History of the Duluth Aerial Lift Bridge
In the early 1900's, Duluth needed a way to connect its downtown area to Minnesota Point. But there was one big problem: the only way to get there was via Lake Avenue and the Duluth Ship Canal. This meant they had to wait for hours each time a ship wanted to pass through while trains, cars and people could cross the bridge.
So what did they do? You built a lift bridge!
The Duluth Aerial Lift Bridge is a movable span-drive lift bridge. Lake Avenue and the Duluth Ship Canal connect Duluth and Minnesota Point. The Duluth Lift Bridge construction project was undertaken by the Modern Steel Structural Company. It was designed and built by Thomas McGilvray and CAP Turner.
A nacelle was suspended from an inverted steel tower at the bottom of the truss of the original 1901–05 Duluth Lift Bridge. This traverse is still in use. Over the years, an elevated roadway replaced the traverse platform, steel towers were lengthened, and new structural supports were added to the original towers to support the roadway counterweight. All this work was completed in 1929.
In 1994, a new bridge was built alongside the Duluth Lift Bridge, which is now used as a bicycle and pedestrian crossing.
The 153 meter span Duluth Lift Bridge can be raised or lowered in less than 15 minutes. The Duluth Aerial Lift Bridge spans 390 feet between towers. The roadway rises to its highest point at 63 feet above sea level, above the average water level of Lake Superior and above the normal navigation level of the Duluth Ship Canal.
Purpose of the Duluth Aerial Lift Bridge
The Duluth Aerial Lift Bridge is a deck typebascule bridgespanning the Duluth Ship Canal in Duluth, Minnesota. It was built in 1905 and has been in continuous use ever since.
The purpose of this bridge is to allow ships to pass through while allowing cars and pedestrians to cross safely and avoid traffic crossing the river. The city began building plans for the bridge in the late 1800s. Local business owners lobbied for construction for years because they wanted access to the larger shipping markets beyond the Duluth port area.
Unable to afford or build one themselves, they appealed to outside sources such as the state government and private industry to subsidize the cost of construction.
Who built the Duluth lift bridge?
CAP Turner or Claude Allen Porter Turner was a structural engineer who built many structures and bridges, primarily in Iowa, Minnesota, and Wisconsin. He is best known for building the Duluth Lift Bridge, considered by many to be a feat of engineering.
At the time of its construction, it was the first bridge of its kind in North America and the West. The Duluth Lift Bridge was also the first bridge to use rigid chords and the first to use an overhead pulley for propulsion.
When was the Duluth Aerial Lift Bridge built?
The Duluth Aerial Lift Bridge was built between 1901 and 1905 and rebuilt in 1929. It is the oldest lift bridge in Minnesota and the second oldest in the United States.
The Duluth Lift Bridge has been repaired four times since 1929. The bridge's antique appearance has been preserved through restoration work that mainly involved replacing the operator's house and selecting steel members. Extensive repairs were made to abutments, deck grids, equipment, superstructure, lighting system and crash barrier. It is also regularly cleaned and repainted.
From 1999 to 2000, the Duluth Aerial Lift Bridge underwent a major renovation, replacing and repainting most of the decks and cables.
The last repair was in 2009. During the last repair, the floor joists were replaced because they were corroded from exposure to water and corrosion-causing elements (e.g. road salt).
Duluth Aerial Lift Bridge features
The Duluth Aerial Lift Bridge is one of the most unique bridges in the world. It is a lift bridge where parts of the bridge are raised to allow tall ships to pass and lowered to allow cars and pedestrians to cross.
The bridge is 390 feet long and can be raised to a full height of 135 feet. The bridge is 153 meters long, making it one of the longest cantilever bridges in the world!
Span drive configuration
The Duluth lift bridge has two spans, each with two drive motors and two lift motors. Each motor is connected to a vertical shaft that turns the rack, which then turns the camshafts that raise and lower the bridge. The gears are lubricated with grease stored in a reservoir on either side of the masts.
The Duluth Lift Bridge is inDuluth, Minnesota, a region in the Midwest of the United States. The bridge connects downtown Duluth to the waterfront and serves as the primary link between US Highway 53 (I-535) and St. Louis County Highway 61, which parallels the Lake Superior shoreline for most of its length.
The bridge can be viewed from many points around Duluth. You can walk to the Thompson Hill Information Center along 8525 West Skyline Parkway for expansive views, or get up close at Canal Park. Canal Park is Duluth's main attraction, with shops and great restaurants lining either side of the canal that runs through downtown. You'll also find street performers throughout downtown Duluth playing music or performing acrobatics for passers-by.
The Duluth Aerial Lift Bridge was designed by Edward Paine, who also designed the nearby Aerial Lift Bridge over Lake Superior. The two bridges are connected by a footbridge that allows you to cross them.
Duluth Aerial Lift Bridge today
Today, the Duluth Aerial Lift Bridge is one of the city's most popular attractions. The city has invested heavily in maintaining the bridge's infrastructure to ensure its safety for tourists and commuters who use it on a daily basis.
The bridge is busier than ever and traffic has become a problem. The bridge carries 7,000 cars per day on an annual average and up to 15,000 vehicles in the summer peak season.
Wanted: Duluth Lift Bridge Operators
The Duluth Lift Bridge is a tourist attraction and a source of pride for the local community. Working on the bridge is considered an honorable role. In 2016 and 2018, two of the bridge's five operators retired and suddenly a rare opportunity presented itself.
Because the bridge is open 24 hours a day, personnel must raise and lower the bridge on a scheduled basis to ensure uninterrupted operations. Bridge operators monitor and control the Duluth Lift Bridge from the Pilot House, a small room in the center of the structure.
The first snowstorm to shut down Duluth's Arial Lift Bridge
After over a hundred years of operation, the Duluth Aerial Lift Bridge became inoperable in 2019 for the first time since its construction. A blizzard left almost two feet of ice and snow in its wake while the bridge froze over and could not be lifted as usual. Maintenance teams worked tirelessly to remove ice and get it running again.
Packing up the Duluth Aerial Lift Bridge
The Duluth Lift Bridge not only connects Canal Park to Park Point and provides access to Duluth Superior Harbor. It is a historic bridge and an engineering marvel.
In June 1973, the bridge became part of the National Register of Historic Places. Five years ago, in 2017, it was designated a National Historic Civil Engineering Landmark by the American Society of Civil Engineers.
If you want to see the Duluth Aerial Lift Bridge for yourself, plan your visit during the May through October peak shipping season. Fewer ships pass through in the off-season, so you may not enjoy the experience as much.
If you're in the area, take a look around31 things to do in Duluth, Minnesota.