Throwback Thursday: Water Under the Bridge, Danger Under the Water
This blog post was written by Dan Antonellis in honor of Brooklyn Bridge Opening Day, which was Wednesday! After 14 years of construction, the Brooklyn Bridge opened to traffic on May 24, 1883, connecting Manhattan and Brooklyn for the first time in history. Dubbed the “eighth wonder of the world,” the bridge changed New York City forever.
Fill a bathtub with water and find a drinking glass. Flip the glass upside down and push it to the bottom of the tub. The water from the tub won’t get inside the glass because of the air trapped inside. It’s about air pressure, physics and other science-related topics I won’t even attempt to explain in this post.
Now stay with me. Picture tiny people standing inside that glass on the bottom of the tub, chipping away at the porcelain with miniature picks and shovels. The air in that glass will eventually run out, so you’ll need a tube poking out of the top of the glass and up and out of the water so that good air can come in and bad air can get out. After all, these tiny people need to breathe as they continue picking away and digging at the bottom of your tub.
Holding a glass upside down at the bottom of the bathtub is the basic premise behind one of the most intriguing and dangerous feats in U.S. engineering and construction history — the building of the underwater foundations that would lie at the bottom of New York’s East River and support the massive towers of the historic Brooklyn Bridge.
The Great Bridge
The vision for “The Great Bridge” (later named the Brooklyn Bridge) was simple enough — to connect Manhattan and Brooklyn and open travel and trade between the two independent cities. (Brooklyn was its own city until it was annexed by New York City in 1898.) The bridge would eventually span 1,600 feet across the river, connecting two masses of land that had been separated by water for millions of years.
The Brooklyn Bridge was designed like most suspension bridges. While they differ aesthetically and hold distinct places in history, they all share certain visual and engineering characteristics in common. Cables that stretch from bridge towers to the highways like giant spider webs. Roads seemingly suspended in air — many of which can span from 2,000 to 7,000 feet long. And of course, the massive towers that stand tall and strong, anchoring the bridge components to the earth and literally holding it all together. Those towers need to be firmly grounded and dug into bedrock, like any other tall structure.
Back in 1869, long before the days of pounding piles into the ground using sophisticated equipment and heavy machinery, there were men, picks and shovels. And plenty of danger to go around.
Suspension bridges require towers to anchor the massive cables that support the structure and roadway. The iconic Brooklyn Bridge towers rise 275 feet in the air. But it’s what occurred under the water line that is the most compelling story behind the bridge’s construction.
The bridge’s two massive towers were built using caissons (pronounced KAY-sins). These were giant upside-down boxes made of southern yellow pine (remember my upside-down glass-in-tub metaphor). The wooden planks of the caisson were bound together by simple nails, with tar to fill the cracks so that water couldn’t seep in.
The caissons, with no bottoms, were submerged until they reached the river bed, 78 feet down on the Manhattan side and 44 feet on the Brooklyn side. Each of these huge underwater caissons would serve as jobsites for 225 men responsible for manually digging the bottom of the muddy river bed until they hit “rock bottom,” or bedrock that was firm enough to support the bridge.
The workers, known as “sandhogs,” were immigrants — mostly Irish, German and Italian — who were paid $2 a day. They would pile into boats early in the morning, just before dark or just before midnight depending on their shifts, and they’d set out for the construction site a few hundred feet from shore where the stone towers would eventually begin to rise from the water.
They’d step off the boats onto creaky wood platforms and descend one by one into a hole, into complete darkness. They would eventually come to a hatch, turn a wheel and descend into an iron chamber called an airlock. And then they’d be sealed within. Claustrophobia be damned.
To get down to the caisson, the airlock would be lowered into the river and filled with compressed air, which would lead to excruciating pain because it dissolved a dangerous amount of gas into the workers’ bloodstreams. Once at the bottom, the trap door of the airlock would open and the workers would climb down into the caisson. And into another dark world.
One at a time, the men would descend a ladder into the actual caisson structure. They would hear the wooden walls creak and settle from the 5,000 pounds of water pressure pushing on the box. Pressurized air was flooded into the chamber to keep the walls from blowing in and the workers from suffocating.
It was hot, muggy, wet and uncomfortable down there — just the conditions you’d expect at the bottom of a deep river. The dense air gave them blinding headaches, itchy skin, bloody noses and slowed heartbeats. They fought the darkness with the soft glow of gas lamps, candles and lanterns.
And then their grueling work would begin. The men would swing their picks and chip away at the river floor. Conversation was minimal. There was much work to be done, and the language barriers among the immigrant workers stymied passing conversation.
To say this was dangerous and difficult work would be a gross understatement (almost as gross as the conditions at the bottom of the river). The men would pick and dig through boulders, rocks and muddy sediment, finding fossils and other mysterious objects along the way. Bathroom breaks were brief and not at all private—buckets in the far corners of the caisson served the purpose well enough.
As the workers dug deeper into the river bed, the caisson would continue to sink deeper into the ground. That’s because as the workers in the caisson were digging at the bottom of the East River, other workers above the river line were constructing the bridge towers. The 60,000 pounds of granite from the towers actually pushed the caissons further into the ground as the workers continued to dig.
The arduous manual labor never stopped, and there would be weeks of digging before the caisson would drop even just a few inches. Dynamite or other explosives obviously weren’t options in an enclosed box under the water. So they just kept digging. By hand.
Leaks were always a threat. At times the water from the East River, which continuously pushed against the sides of the caisson, would seep inside and fill the work area with water. Men would need to quickly patch the cracks with tar to plug the leaks. To keep the work moving. And to stay alive.
After grueling shifts at the depths of the river, the workers would eventually return to the surface. That led to even greater physical challenges.
Most workers returned too quickly, causing nitrogen bubbles in their blood—the bends, then known as “Caisson disease.” All this in an era with no decompression chambers, or even ibuprofen. More than 100 workers suffered from the disease, experiencing joint pain, paralysis, convulsions, numbness, speech impediments and, in some cases, death.
In fact Washington Roebling, who was the Chief Engineer of the project and inventor of the caissons (and veteran of the Civil War, including the battles of Gettysburg and Antietam) suffered from the bends himself after helping to fight a fire in one of the caissons—the condition left him partially paralyzed for the rest of his life. He was forced to watch through a telescope while his wife Emily took charge of the construction project. The bridge had already claimed his father, John Augustus Roebling, who was the original visionary and designer of the Brooklyn Bridge. John Roebling died of tetanus after crushing his foot between a boat and a dock while surveying the bridge location before construction began.
Eventually, 14 years after construction began, the digging under the river was complete. The abandoned caissons lingered below to play out a second act as formwork: concrete was poured into the caissons, becoming part of the foundation. They remain there to this day, under the East River, silent and invisible monuments to the men who toiled in appalling and dangerous conditions under the waterline. The anonymous men who built the Brooklyn Bridge.
Construction of the bridge required 600 workers and cost $15 million (more than $320 million in today’s dollars). Now 135 years old, this iconic feature of the New York City skyline still carries approximately 150,000 vehicles and pedestrians every day. Most of whom never heard about how it was built, about the brave men who built it, or the secrets that lie at the bottom of the river bed, still supporting the beautiful and iconic bridge above.
This post was written by Suffolk Construction’s Vice President of Marketing and Communications Dan Antonellis. If you have questions, Dan can be reached at firstname.lastname@example.org or you can connect with him on LinkedIn here.
Credit where credit is due
The inspiration behind this post and the “bathtub” metaphor came from the podcast The Memory Palace, Episode 81, “Below, from Above.” The Memory Palace podcast, led by master storyteller Nate DiMeo, is a great find for people who love history, appreciate a good story and believe that “truth is stranger than fiction.” Do yourself a favor and plug in to The Memory Palace and start listening! This post also drew inspiration from master historian and national treasure David McCullough and his wonderfully written book The Great Bridge.