Great Lakes Moving Bridges: How they work and why we love them

Great Lakes Moving Bridges: How they work and why we love them
November 2, 2022 James Proffitt, Great Lakes Now

They stop dozens of vehicles creating traffic jams so that a single boat can dawdle through and sometimes they make us late. They’re usually very old and expensive to maintain and operate and holy smokes, they move slow as cold molasses.

But seriously, aren’t they great?

“It can definitely be an inconvenience, but in all reality it’s only a few minutes every hour,” Port Clinton Mayor Mike Snider said. “So it’s not really a big deal. And plus it’s just a really cool thing to have in our city.”

He pointed out that people visiting Port Clinton, Ohio which is situated where the Portage River meets Lake Erie, are often intrigued by the drawbridge. In fact, some tourists who arrive at the Jet Express, a ferry that takes people to and from South Bass Island, actually miss their ferry and take the next one simply to stay on the mainland and watch the bridge open and close.

“People are always excited to see it opening,” Snider said, making the caveat that his statement does not always include drivers stopped in traffic waiting to cross. “It’s been around almost 100 years and it’s actually on our city seal.”

Moving bridges historically played, and still do, crucial roles in the development and commerce of dozens of Great Lakes cities. And folks who have never seen one operate are often mesmerized by their sheer size and the fact they really do move – just like in the movies during car chases.

Milwaukee awash with moving bridges

While the city ranks 31st in the nation for population size, it ranks second in the nation – behind Chicago – in number of moving bridges, with about 20 inside the city limits. And not many people depend on the bridges for their livelihood more than Jake Chianelli, owner of the Milwaukee Boat Line. His two vessels carry people beneath nearly a dozen moving bridges to get down the Milwaukee River and onto Lake Michigan.

His tours, which narrate the history of Milwaukee, include the history of its bridges, of course.

“They’re a massive highlight of the tours,” he said. “Unlike Chicago, which raised its bridges 10 feet after it burned down, in Milwaukee there’s not a lot of clearance. So we do have the most number of bridge openings per year in the nation. It’s a mix of bascule bridges and vertical lift bridges.”

The difference, he said, is that bascule bridges have two moving spans that meet in the middle, each raising upward to its own side of the river. On lift bridges, the entire deck rises and lowers like an elevator. The bridges, according to Chianelli, help tell the city’s history, including why some of the streets are crooked and why some bridges approach the river at an angle. The reason? The Milwaukee Bridge War.

The city’s three original founders were competitive, so much so that two of the three intentionally constructed street grids that did not line up, eventually requiring bridges that ran diagonally across the river. A brief period of rivalry between the trio of original settlements included destruction of bridges and skirmishes between each communities’ residents during the 1840s. Things settled down after Kilbourntown, Juneautown and Walker’s Point were incorporated into the City of Milwaukee a short time later.

Of course that history is long past, Chianelli said, and the city operates a first-class transportation system when it comes to bridges. Just one hiccup in bridge operations could put his business under water, literally and figuratively. Without every bridge opening and closing properly, he can’t get customers on the water and to the lake.

“It’s been a few years but they had some broken parts, especially with the hydraulic components probably made in the 1960s, and it took maybe a month to get the parts in,” he said. “So the city brought in a crane and lifted up a bridge and put some I-beams down and the bridge would stay up and the road stayed closed.”

While the city operates a top-notch collection of bridges, it isn’t out of pure generosity. The Rivers and Harbors Appropriation Act of 1899 requires that navigable waterways in the United States be reasonably free of major obstructions, such as bridges. And if bridges do obstruct traffic, the United States Coast Guard has the authority to remove or rebuild them. Thus, boats on federal waterways have the right to get through. And free of charge.

Chianelli and other operators with regular schedules often work with bridge operators. In other cases, vessels hail a bridge operator either on a marine radio or via cell phone. Some bridges have set times they open and close, with boat operators idling until the scheduled opening.

In Duluth, however, the bridges provide much more than a practical way for ships and boats to access Duluth Harbor.

Duluth’s two special bridges: Minnesota Slip and Aerial Lift

Most moving bridges are vintage, but not the Minnesota Slip Bridge, which was constructed in 1991 at a cost of about $800,000. While it allows recreational boats docked in the slip to access Lake Superior during the season, it also allows pedestrians and bike traffic to move between a popular shopping district and the city’s convention and entertainment center to the tune of about a half million people a year. It raises between 2,500 and 3,000 times per season, remaining lowered from November through April.

But the city’s most iconic bridge is the Aerial Lift Bridge, a monster that raises its deck to a height of 135 feet above the waters of the Duluth Ship Canal, allowing all vessels to easily pass below. The city often features the lift bridge on its logos and public imagery.

“The bridge is considered to be a local landmark and was added to the National Register of Historic Places in 1973,” Aerial Lift Bridge supervisor David Campbell said. “It provides a connection from the Canal Park district of the city out to Minnesota Point. Many visitors will come to Duluth and make it a point to stop by and see a 1,000-foot lake vessel pass under the bridge.”

While it lifts for commercial marine traffic on demand, the bridge also operates on the hour and half hour for recreational vessels during the season. During some winter months, mariners must request an opening 12 hours in advance to pass under.

“Construction began in 1929 and it became operational in 1930,” Campbell said. “The roadway lifting section weighs approximately 1,000 tons and each counterweight weighs around 500 tons.”

According to Campbell, the physical act of raising and lowering the bridge is simple for operators – it’s keeping traffic and people in check that’s the most difficult.

“It doesn’t matter what time of day, what day of the week, you see people do things that make you shake your head,” he said. “We control traffic, we put the gates down but the one thing we cannot control is the people, and what they’re going to do. There’s times people want to hang on the bottom or they’ll want to run onto the bridge, so the job is much more stressful than it is physical.”

Despite the stress, he said, operators stick around.

“Most people once they’re at the bridge they’re here 15, 20 years. We’ve had people retire after putting in 30 years,” Campbell said.

Drawbridges embraced by Milwaukee Riverkeeper

Cheryl Nenn describes Milwaukee Riverkeeper as a science-based advocacy organization whose aim is to protect water quality and wildlife habitat. So how does that mission intersect with drawbridges? Nenn, a long-time waterkeeper, said they protect about 900 square miles of watershed, which ends around downtown Milwaukee.

“People see us out and about on the river often doing our work and these bridges are a very active part of the city,” she said. “We try to connect people to the river through clean-up and paddle events and other projects. A lot of people, their main connection to the river is driving over these bridges everyday. But also, boaters are connected to the river through the bridges, since most all of them require bridge openings.”

Nenn said getting onto the water in Milwaukee is a great experience and one that tends to make people think about and care more about the city’s rivers.

“Seeing the city from that perspective is really an amazing way to see Milwaukee – I think that’s a big part of the character of town and it really ties to the history of the city,” she said.

The three major Milwaukee rivers at one time provided crucial market access to timber and other natural resources in southeast Wisconsin at a time when river traffic was paramount, and the same is true for most Great Lakes rivers and their moving bridges.

“They started out for industry, though now they’re more for recreation,” said Nathan Holth, a bridge historian who operates a site that documents historical bridges in the U.S.

Now, most moving bridges serve the needs of the general public and recreational river traffic like tours, sailboats, smaller commercial operators and pleasure boaters.

“But in Chicago for instance, the Calumet River bridges are still used by commercial barges and other industrial traffic,” Holth said. “And the reason for moving bridges there and in most cities is there isn’t a lot of room to build long, high approaches because you’re right in the middle of downtown.”

Moving bridges are finely tuned machines

At first glance, it would appear that some amazingly powerful mechanism must be in play to move bridge spans or decks slowly up and down. But the truth is, it doesn’t take much power at all, despite the massive weight of the spans, explains an Ohio Department of Transportation, or ODOT, official.

“Each leaf of the bascule spans in Port Clinton weighs 675,000 pounds,” said Tim Keller, an administrator at ODOT’s Office of Structural Engineering. “The main mechanisms are motors that drive a shaft connected to gears that raise the bridge. The counterweights are concrete blocks with lead shot that fill the voids in the concrete.”

Those massive 330-plus ton counterweights are hidden from public view underground on either riverbank, and are measured down to the pounds to balance each span perfectly, much like equal weights on either end of a playground teeter-totter. A video posted by Holth explains how moving bridges and counterweights work. With the counterweights matched to the span weights, very little energy is required to raise and lower them.

The Port Clinton drawbridge, constructed in 1933, received a major overhaul and was shut down during a 10-month period spanning 2017 and 2018, at a price tag of $13.5 million. The bridge, according to ODOT Historic Bridge Program Manager Tom Barrett, was partly designed by a prolific architect who worked for the state from the 1930s through the 1970s, Josephine Powers.

And very handsomely designed it was, Holth said, citing the classic design and matching control houses at either end.

“That bridge is a particularly good example of where they really wanted it to look nice,” he said. “Aesthetics played a big part so they really designed it to look beautiful.”

In earlier days bridges often had multiple tenders, Holth said, since there was a responsibility not only for road traffic on both sides of the bridge, but also for anything beneath the bridge and approaching the bridge from two directions. But that’s changed with closed-circuit TV and video cameras. In some cases, bridge operators at one site operate other bridges, up to three total, remotely. That practice has come under fire recently after a Rhode Island man died after being caught on a rising bridge in Milwaukee. The bridge was being operated remotely from another bridge house. But incidents involving injury or death on drawbridges are rare.

Everybody loves something giant that moves

“I’ve definitely seen a bunch of tourists stand by in awe of the bridges,” said Ian Thompson, communications director at Visit Milwaukee. “It’s definitely something you just don’t see many other places, at least from the travels I’ve been able to complete. Especially the lift bridges.”

Thompson said sometimes bridges close for maintenance, though he’s never seen one completely stop working mid-raising or lowering.

“The public works department does a pretty good job of ensuring that all our bridges are well maintained and of course, planning accordingly for that,” he said.

Nenn said that while Chicago has more bridges, Milwaukee tops the nation in bridge openings at more than 27,000 per year.

“They really are wonderful,” she said. “They’re beautiful structures and that’s why we’ve been active in trying to preserve them and really big advocates of water access for kayaks, canoes and motorized boats.”

And Holth agrees.

“There’s a lot of engineering going on when it comes to any moving bridge, and for me I have an appreciation for the designs, intricacy like the rivets and a lattice truss design, geometry,” he said. “But for most regular people I think it’s just that they move.”

Barrett attributes moving bridges’ popularity to a combination of things.

“Moveable bridges literally stop traffic and there’s a boat coming through, you have the water and all the fun stuff going on at once,” he said.

Campbell said for him and his staff, the bridges are cool, though remain a serious task at hand. Not so for everyone else.

“The Aerial Lift Bridge is the icon of the city, no doubt, and it’s a huge tourist attraction in this area,” he said. “If there’s a boat coming in there’s people line up on the pier to watch, especially in the summer the Canal Park District is very busy. When we start going up everybody starts running to the pier to watch the bridge and see what’s coming in.”

Catch more news at Great Lakes Now: 

Coastal craft beers come to Lake Superior

A look back on Queen Elizabeth’s Great Lakes tour

Featured image: The Chicago River has bridges that open and bridges that stay open. (Photo Credit: Sandra Svoboda/Great Lakes Now)


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