History Made Every Day™

Sandhogs and the Brooklyn Bridge

Sandhogs have had a part in New York City's most impressive, and toughest, construction projects ever since the 1870s, when they broke ground on their first big job—the iconic Brooklyn Bridge.

In 1867, New York legislators approved engineer John Augustus Roebling's plan for a suspension bridge over the East River between Manhattan and Brooklyn. Roebling's bridge would be a technological marvel: It would have the world's longest span (1,600 feet from tower to tower); it would be the first to use steel wires, cables and trusses; and it would be the first to excavate the riverbed by sending workers—the Sandhogs—armed with explosives into fire-prone underwater chambers called caissons.

Working in the Caissons

Roebling died after a freak accident just as construction was getting underway, and his son Washington took over the bridge project. It was the younger Roebling who designed the caissons that housed the project's Sandhogs—mostly immigrant workers who earned about $2 a day—as they prepared to sink the bridge's foundation into the riverbed. These caissons were airtight wooden chambers, 160 feet long and 100 feet wide, which were pinned to the river's floor by enormous granite blocks. Inside these giant boxes, the Sandhogs used shovels and dynamite to clear away the mud and boulders at the bottom of the river. Each week, the caissons inched closer to the bedrock.

Getting the Bends

To get down into the caissons, workers rode in small iron containers called airlocks. As the airlock descended into the river—44 feet to the Brooklyn caisson and 78 feet to the Manhattan one—it filled with compressed air. This air made it possible to breathe in the caisson and kept the water from seeping in, but it also dissolved a dangerous amount of gas into the workers' bloodstreams.

Underwater, the workers in the caisson were uncomfortable—the hot, dense air gave them blinding headaches, itchy skin, bloody noses and slowed heartbeats—but relatively safe. As they came back to the surface in the airlocks, however, the dissolved gases in their blood were quickly released. This often caused a constellation of painful symptoms known as "caisson disease": excruciating joint pain (many people called the disease "the bends" because those who had it were frequently unable to straighten their arms or legs) along with paralysis, convulsions, numbness, speech impediments, and in some cases, death. Even Roebling himself contracted the disease. Though he survived, he was an invalid for the rest of this life, and was forced to watch with a telescope while his wife Emily took charge of the bridge's construction.

By the early 20th century, scientists had figured out that if the airlocks traveled to the river's surface more gradually, slowing the workers' decompression, the bends could be prevented altogether. In 1909, New York's legislature passed the nation's first caisson-safety laws to protect the Sandhogs digging railway tunnels under the Hudson and East rivers.