In the city of Duluth, Minnesota, one bridge has been keeping people safe for more than a century. It’s the only lift-span bridge design of its kind in the world, and it’s a true feat of engineering. The bridge has withstood fires, ice jams, and many other threats.
It’s called the Duluth Aerial Lift Bridge, one of the city’s most iconic landmarks.
The Duluth Aerial Lift Bridge
The Duluth Aerial Lift Bridge was built between 1901 and 1905. Boats can pass under the bridge and avoid boat traffic as they make their way into the Duluth-Superior harbor. The bridge was designed so that the center section could be raised to allow tall ships to pass through.
Today, the bridge is used primarily by recreational boats although it is still open for commercial traffic.
Operated by a bridge tender, the center section is lowered and raised according to a published lift schedule. The Duluth Aerial Lift Bridge is among the most recognizable landmarks in the city 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 1900s, Duluth needed a way to connect its city center with Minnesota Point. But there was one major problem: the only way to get there was over Lake Avenue and across the Duluth Ship Canal. This meant that every time a boat wanted to pass through, they had to wait for hours while trains, cars, and people could cross the bridge.
So, what did they do? They built an aerial lift bridge!
The Duluth Aerial Lift Bridge is a span-drive moveable lift bridge. Lake Avenue and the Duluth Ship Canal link Duluth and Minnesota Point. The construction project of the Duluth Lift Bridge was done by the Modern Steel Structural Company. It was planned and built by Thomas McGilvray and CAP Turner, respectively.
A gondola was hung from the underside of the truss of the original 1901 to 1905 Duluth Lift Bridge by an inverted steel tower. This truss is still in use. Over the years, an elevated highway replaced the traversing platform, steel towers were extended, and new structural support was included in the original towers to bear the roadway’s counterweight. All of this work was completed in 1929.
In 1994, a new bridge was built next to the Duluth Lift Bridge which is now used as a bicycle and pedestrian crossing.
Spanning 153 meters, the Duluth Lift Bridge can be raised or lowered in under 15 minutes. The Duluth Aerial Lift Bridge stretches 390 feet between towers. The roadway rises to its highest point at 63 feet above water level, above the average water level of Lake Superior, and above the Duluth Ship Canal’s normal shipping level.
Purpose of the Duluth Aerial Lift Bridge
The Duluth Aerial Lift Bridge is a deck-type bascule bridge that spans the Duluth Ship Canal in Duluth, Minnesota. It was built in 1905 and has been continuously used since then.
The purpose of this bridge is to allow ships to pass through while still allowing cars and pedestrians to cross over safely and avoid cross-river traffic. The city began building plans for the bridge in the late 1800s. Local business owners lobbied for years to have it built because they wanted access to the larger shipping markets beyond the Duluth harbor area.
Since they were unable to afford or build one themselves, they appealed to outside sources like the state government and private industry to subsidize the cost of its construction.
Who Built the Duluth Aerial Lift Bridge?
CAP Turner or Claude Allen Porter Turner was a structural engineer who built many structures and bridges, mainly in Iowa, Minnesota, and Wisconsin. He is best known for building the Duluth Lift Bridge, which many consider a feat of engineering.
At the time when it was constructed, it was the first bridge of its kind in North America and in the West. Duluth Lift Bridge was also the first stiff-girded bridge 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 modified in 1929. It’s 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, which mainly involved replacing the operator’s house and selecting structural steel parts. Extensive repairs have been made to its abutments, deck grating, equipment, superstructure, lighting system, and guardrail. It is also cleaned and repainted periodically.
From 1999 to 2000, the Duluth Aerial Lift Bridge received a major renovation which included replacing most of its deck and cables as well as repainting it.
The most recent repair was in 2009. In the last batch of repairs, the floor beams were replaced because they had corroded from exposure to water and corrosion-causing elements (such as 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 sections of the bridge are raised to allow tall ships to pass through and lowered so that cars and pedestrians can cross over.
The bridge is 390 feet and can be raised to a full height of 135 feet. The bridge has a length of 153 meters, 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 gear rack which then turns the camshafts that raise and lower the bridge. The gears are lubricated by grease which is stored in a reservoir on either side of the lift towers.
The Duluth Lift Bridge is in Duluth, Minnesota, a Midwestern region in the United States. The bridge connects Duluth’s downtown to its waterfront and serves as a major connection between US Highway 53 (I-535) and St. Louis County Highway 61, which runs parallel to Lake Superior’s shoreline for most of its length.
The bridge can be viewed from many points around Duluth. You can go to the Thompson Hill Information Center along 8525 West Skyline Parkway for sweeping views or see it up close at Canal Park. Canal Park is Duluth’s main attraction, with shops and major restaurants lining both sides of the canal that goes through the town’s center. You’ll also find street performers throughout downtown Duluth playing music or performing acrobatics for passersby.
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 pedestrian bridge walkway that allows you to cross between them.
Duluth Aerial Lift Bridge Today
Today, the Duluth Aerial Lift Bridge is one of the most popular attractions in the city. The city has heavily invested in maintaining the infrastructure of the bridge, ensuring its safety for tourists and commuters who use it every day.
The bridge is as busy as ever and traffic has become a problem. The bridge handles an annual average of 7,000 cars per day and as many as 15,000 vehicles during 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 at the bridge is considered an honorable role. In 2016 and 2018, two of the bridge’s five operators retired and a rare opportunity suddenly became available.
Since the bridge is open 24/7, its staff must raise and lower the bridge on schedule to ensure its nonstop operation. Bridge operators monitor and control the Duluth Lift Bridge from the Pilot House, a small room in the middle of the structure.
The First Snowstorm That Paralyzed the Duluth Arial Lift Bridge
After operating for over a hundred years, the Duluth Aerial Lift Bridge became inoperable in 2019 for the first time since its construction. A snowstorm left almost two feet of ice and snow while the bridge froze over and couldn’t be lifted as usual. Maintenance crews worked tirelessly to remove ice and get it working again.
Wrapping Up the Duluth Aerial Lift Bridge
The Duluth Lift Bridge does more than connect Canal Park with Park Point and provide access to the Duluth-Superior harbor. It’s 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, the American Society of Civil Engineers designated it as a National Historic Civil Engineering Landmark.
If you’d like to see the Duluth Aerial Lift Bridge for yourself, time your visit during the peak shipping season from May to October. During the off-season, fewer ships are passing through so you may not get to enjoy the experience as much.
While you’re in the area, check out 31 Things to Do in Duluth, Minnesota.