At noon on May 3, 1929, a crew of ironworkers stood at the advancing tip of the Bayonne Bridge arch on the New Jersey shore, looking across the Kill Van Kull toward the opposite tip rising from the Staten Island side. More than a thousand feet of open air separated the two points. The tidal strait ran beneath them. The temporary restraining cables attached to the arch tip above them were taut under the weight of the four-hundred-foot steel rib that had been cantilevered out from the Bayonne shore over the preceding months.

If those cables failed, the tip of the arch and every man on it would drop into the water. The cables held. The ironworkers returned to their work. What they were building would take two more years to complete, and when finished it would be the longest steel arch ever built anywhere in the world.

The men building it were paid six dollars a day at a construction site about to face the worst economic collapse in American history. Their names exist in payroll records. They exist nowhere else a person might look for them today. The Kill Van Kull is a tidal strait three and a half miles long, separating the north shore of Staten Island from the Bayonne peninsula in New Jersey.

It connects Newark Bay to the west with the Upper Bay of New York Harbor to the east. In 1929, the shores of the Kill Van Kull were among the most industrially developed waterfronts in the United States. The Bayonne shore was dominated by the Standard Oil of New Jersey refineries, whose tank farms stretched along the waterfront for more than a mile and whose operations had defined the character of Bayonne since the 1870s. The Staten Island shore had its own refineries, its own tank farms, its own chemical plants, its own piers.

The strait between them was the navigation channel through which tankers, freighters, and heavy commercial vessels moved between the Upper Bay and the ports of Newark, Elizabeth, and Bayonne. It was among the busiest commercial waterways in the United States, and in 1927, no bridge crossed it. The absence of a bridge was not an oversight. It was the result of the specific physical requirements any crossing over the Kill Van Kull had to satisfy.

The navigation channel was deep. The ships using it had air drafts—the vertical distance from the waterline to the highest point of a ship’s structure—that required substantial clearance above the water surface. A bridge too low would either block some ships entirely or force them to reduce cargo to lower their draft, which was economically equivalent to reducing the capacity of the port. In 1925, when the Port of New York Authority began a serious engineering analysis of a Kill Van Kull crossing, the required clearance above mean high water was set at 150 feet.

That is roughly the height of a fifteen-story building above the surface of the strait. To achieve that clearance with a main span long enough to cross the Kill Van Kull without placing a pier in the navigation channel required a main span of at least 1,600 feet. In 1925, no steel arch bridge anywhere in the world possessed a main span of 1,600 feet. The bridge that would cross the Kill Van Kull, by the very geometry of the shipping channel’s requirements, would be the longest steel arch ever built before a single piece of its steel was even ordered.

The man who designed it was Othmar Hermann Ammann. He was forty-six years old in 1925 when the Port of New York Authority gave him the assignment, and he had spent the previous twenty-one years in the United States preparing for problems exactly this size. Ammann was born in 1879 in Schaffhausen, a Swiss town on the Rhine whose identity was shaped by the waterfalls at its center and by the covered wooden bridge that had crossed the river there since the fourteenth century. He grew up with bridges as part of the scenery he moved through without much thought.

He studied civil engineering at the Swiss Federal Institute of Technology in Zurich, and came to the United States in 1904 with a letter of introduction to an engineering firm in New York and a conviction that the largest and most important structural problems of his era were in America, not Europe. He spent the next eighteen years working under Gustav Lindenthal, who at that time was one of the most prominent bridge engineers in the United States. Lindenthal had built the Hell Gate Bridge over New York’s East River, a steel arch with a main span of 977 feet. That bridge, when opened in 1916, was the longest steel arch in the world and one of the most heavily loaded bridge structures ever erected over a waterway.

Ammann worked on Hell Gate and learned from that experience what a massive steel arch demanded in structural analysis and construction logistics, and what final form it produced that could bear loads and resist the forces of wind, temperature, and decades of traffic. He also learned something about Lindenthal’s engineering philosophy, and about where his own thinking diverged from it. Lindenthal believed in mass. His structures were heavily designed.

They resisted forces through the strength of materials and through the sheer weight of the steel and concrete they were made of. Hell Gate was massive in a way that reflected its function. It carried Pennsylvania Railroad trains loaded to the maximum loads early-twentieth-century railroad bridges were required to handle. But it was also massive in a way that reflected Lindenthal’s conviction that a bridge should look capable of carrying what it carried.

Looking capable meant being built with a visible margin of material that made the strength apparent to anyone who looked at it. That margin was not waste. For Lindenthal it was the visible embodiment of structural safety. Ammann did not disagree with Lindenthal about the importance of strength.

He disagreed about the relationship between strength and the quantity of material. What Ammann concluded from his years of study and work under Lindenthal was that a bridge could be strong without being heavy. The precise calibration of structural engineering could produce a structure that carried its loads efficiently, without the excess material Lindenthal considered necessary. Strength lay in the calculations.

If the calculations were correct, the material was sufficient. Whatever remained beyond sufficiency counted as waste to Ammann. This was not a minor philosophical difference. It produced different bridges at different costs with different appearances, and it eventually put the two men on opposite sides.

The break between them became final in the early 1920s over the question of a Hudson River crossing. Lindenthal proposed an unusually ambitious bridge, a multi-deck structure carrying rail and vehicular traffic, with approaches and anchorages that would have required redesigning the riverfronts on both sides. Ammann proposed something more precisely calibrated to what the traffic of that era actually required. The Port of New York Authority chose Ammann’s proposal.

Lindenthal’s bridge was never built. The bridge Ammann designed instead, the George Washington Bridge, opened in October 1931 with a main suspension span of 4,760 feet, the longest in the world at that moment. Ammann was simultaneously designing and supervising the construction of the longest suspension bridge in the world and the longest steel arch in the world. Both would open within weeks of each other in the autumn of 1931.

He was fifty-two years old. What Ammann understood about the Bayonne problem was that the arch was the correct structural solution to what the crossing required. A suspension bridge of the necessary span was possible—the George Washington Bridge proved that—but a suspension bridge required cable anchorages, and cable anchorages on the industrial waterfront of the Kill Van Kull meant seizing land occupied by oil refineries whose owners had no wish to move. An arch bridge anchors its horizontal thrust in abutments rather than cable anchorages, and abutments fit more easily into the existing waterfront space on both shores.

The arch was also structurally suited to a span of 1,675 feet, the dimension Ammann settled on for the main span of the Kill Bridge. A steel rib arch with properly proportioned dimensions and a carefully calculated rise-to-span ratio converts the vertical load of the roadway and its traffic into compression along the arch ribs, and transmits that compression to the abutments at each end. Compression is something large steel sections handle very well. The mathematics of the loads led to the arch design.

Ammann followed that mathematics. The main span of the Bayonne Bridge is 1,675 feet, measured between the abutments at the points where the arch rests on each shore. The arch ribs—parallel steel trusses forming the structural backbone of the bridge—rise in a parabolic curve from the skewbacks near the water’s edge to the crown at the center of the span. The parabola is the natural shape of a flexible cable under a uniform vertical load, and in an arch, the same curve describes the path along which the compressive force travels through the rib.

A parabolic arch under uniform load experiences no bending in its ribs—only pure compression—which makes it structurally efficient in a way other curves are not. Ammann’s arch was not a perfect parabola. The loads on a highway bridge are not uniform, and the ribs had to handle load combinations that produced bending in addition to compression. But the parabola was the base form from which the refinements were derived.

The total span of 1,675 feet was, in 1931, the longest steel arch span ever built. It was 23 feet longer than the Hell Gate Bridge that Lindenthal had completed fifteen years earlier—the bridge on which Ammann had worked as Lindenthal’s subordinate. That record stood for forty-six years. In 1977, the New River Gorge Bridge in West Virginia opened with a main span of 1,710 feet to surpass it.

For forty-six years, a steel arch crossing a tidal industrial strait in the New York harbor complex was the longest of its kind in the world. No certificate of that record was displayed anywhere on the bridge. It was not on the minds of the men who built it. They were on the bridge because the contract required it, the schedule drove it, and the wages, modest as they were, were wages in an economy about to stop providing them to a large portion of the workforce.

Construction began in 1927. The foundation work came first. The abutments that would receive the arch’s thrust at each skewback required massive concrete structures buried deep enough in the ground to resist the inclined compressive forces the arch would generate, without sliding or rotating. The arch thrust is not vertical.

It is inclined, pressing outward and downward along the line of the rib at the skewback, and the abutment had to resist that force in both the horizontal and vertical directions at once. Ground conditions on both shores were examined before construction began. The Bayonne shore sat on material disturbed by decades of industrial occupation. The Staten Island shore had its own conditions.

The foundations were built to the depths the examination determined were sufficient. The steel erection contract went to the American Bridge Company. The men who worked on the steel of the Bayonne Bridge came from the community of ironworkers who had been building the high steel structures of the Northeast for decades. Among them were men from Kahnawake, the Mohawk nation community on the south bank of the St.

Lawrence River opposite Montreal. The Mohawks of Kahnawake had been building high steel since 1886, when workers from the community were first employed on a railroad bridge over the St. Lawrence. In the decades that followed, they worked on bridges and towers in New York, Chicago, and Detroit, developing a reputation as ironworkers of exceptional quality at working exposed steel at extreme heights.

That reputation was built on something real. The work required a specific combination of physical balance, spatial reasoning under dynamic conditions, and an approach to height that allowed a man to work at full mental capacity while the steel swayed, the wind moved, and the ground stayed far below and never came closer. This was not a trait distributed randomly among populations. It was a skill developed across generations of men who did this work and passed the habits of mind and body to their sons in a community where this kind of work was familiar rather than alien.

The Kahnawake men who came to the Bayonne Bridge lived in boarding houses in Bayonne and Staten Island during the erection period. They came as the work required, knowing the job was the purpose for which they had come, and they would return to Kahnawake when it ended. That was how the steel trade worked. Men followed the steel.

What made the Bayonne Bridge unique was the geometry of the arch and what that geometry demanded of the men who erected it. A steel arch cannot be built the way a girder bridge or a truss bridge is built. You cannot build it from end to end in a simple sequence, because an incomplete arch is not an arch. An arch functions structurally only when the two halves meet at the crown and the path of compression through the ribs is completed from abutment to abutment.

Before that moment, what exists on each shore is not an arch. It is a cantilever, extending outward from a fixed base with nothing at the far end to balance it. A cantilever eight hundred feet long over the Kill Van Kull, loaded with the weight of its own steel and the construction loads imposed by the erection process, generates bending forces the arch ribs alone cannot withstand. The temporary cable system was the means of restraint.

As the arch ribs extended outward from each shore, section by section, each new section bolted and riveted to its predecessor, temporary backstay cables were attached to the advancing cantilever tip and run at an angle to anchorages embedded in concrete behind the abutments on shore. The cables held the cantilever rib against the tendency of its own weight to rotate the tip downward toward the water. With each new section added to the advancing tip, the forces in the temporary cables increased, and the anchorages had to resist those increasing forces without giving way. The design of the temporary cable system required structural analysis as precise as the analysis of the final bridge itself.

Any failure of the temporary cables during erection would drop the cantilever rib into the Kill Van Kull. Every man on the rib at the moment of failure would fall with it. The cables were designed not to fail. They held throughout the erection of both halves of the arch.

The ironworkers placing and connecting the arch rib sections worked on surfaces that were not horizontal. The arch rises steeply from the abutments and gradually flattens as it approaches the crown. Near the abutments, the rib surface was steeply inclined, approaching vertical in the steepest sections. Higher up the arch, the surface was less steep.

Near the crown, it approached horizontal. The nature of the work changed with the curvature. In the steep lower sections, a man placing a piece of steel worked on something like the side of a hill with open air on both sides. In the upper parts, near the crown, he worked on a long narrow slope, with the Kill Van Kull current visible below on one side and the rooftops of Bayonne or Staten Island on the other.

There was no safety net. There was no procedure that reduced the risk to zero. There was the work and the height at which the work had to be done, plus the training and composure that distinguished the man capable of doing it from the man who was not. The riveting gangs fastened every connection as construction progressed.

Each gang consisted of four men. The heater tended the portable furnace and heated rivets until they reached the temperature at which the steel became workable. The catcher, positioned with a catching bucket, received the hot rivet when the heater tossed it across the connection. The bucker-up pressed the pre-formed head of the rivet against the steel of the connection using a supporting bar, holding it in place against the force that would be applied to the other end.

The riveter hammered that other end with a pneumatic hammer, forming the closing head that permanently locked the rivet into the hole. The pneumatic hammers were heavy and loud enough to make conversation impossible, requiring both hands and full body weight to control against the recoil force. On the sloping surface of an arch rib two hundred feet above the Kill Van Kull, the riveter handled a pneumatic hammer at a connection at an awkward angle, standing on uneven steel, with New York Harbor winds wrapping around him and the waters of the Kill visible below. He did this as a matter of the ordinary requirements of the job.

The Great Depression reached the Bayonne Bridge construction site in October 1929. The market collapsed. In the months that followed, the collapse continued. By 1931, unemployment in New Jersey was approaching twenty percent.

Construction work on the Bayonne Bridge did not stop. It could not stop. The bonds that financed the project had been sold to investors who bought them on the understanding that the bridge would be built, that it would open on schedule, and that it would generate enough toll revenue to repay the debt. The bond agreements set the schedule.

The Port of New York Authority had no authority to break those agreements. The schedule proceeded regardless of what was happening in the economy outside the perimeter of the construction site. What the Depression changed was the context in which workers experienced their jobs. A man working on the Bayonne Bridge in 1930 held a job in an economy that was taking jobs away from everyone who did not already have one.

The labor market that existed when construction began in 1928 was not the labor market of 1931. Men who had been earning wages in manufacturing and other construction trades no longer earned them. At the hiring gate of the Bayonne Bridge, there were men available who had not been there before—men who needed work in an environment where work was disappearing, and their presence at the gate did not improve the negotiating position of the men already employed on the project. The wages were what the market set under the conditions the Depression imposed.

Whether those wages were proportional to the risks of the work at the tip of an arch suspended over the Kill Van Kull is a question the payroll records do not address, because they were prepared by the people who set those wages. Four workers died during the construction of the Bayonne Bridge. Three of them died from falls off the structure. One died when a piece of equipment struck him during the construction of the approach spans.

The deaths were investigated by the contractor and reported to the relevant New Jersey authorities under the framework of the workers’ compensation law that existed in the early 1930s. That framework provided for investigation of the immediate circumstances of each death, and for compensation to the families of the deceased through a process administered by insurance companies and the contractor. The families received financial settlements. Whether those settlements were adequate to what the families lost is a question the settlement records do not answer, because they were prepared by the people who set the settlement amounts.

The names of the four men appear in the accident documents. They appear nowhere on the bridge. The closing of the arch crown was carried out in the autumn of 1931. The two cantilevered halves of the arch, which had been growing toward each other from opposite shores for more than two years, were brought into final alignment through fine adjustment of the temporary cable tensions on both sides, and the crown pins were driven to complete the connection.

Steel changes dimension with temperature. A steel arch 1,675 feet long is not the same length at 45 degrees Fahrenheit as it is at 70 degrees. Thermal contraction was expected, and Ammann’s engineers had calculated it. The closure was planned for an autumn temperature range that would produce dimensional conditions within the tolerances set by the design.

The ironworkers who drove the crown pins in October 1931 worked at the highest point of the arch structure, at a height that put the rooftops on both shores far below them, with views of the harbor in multiple directions, in temperatures in the forties, with winds blowing in from the Upper Bay. They drove the pins into place. The two halves became one structure. The arch was complete.

When the temporary restraining cables were released after the crown closure, the arch became what it had been designed to be from the start: a compressive structure in which the weight of the roadway and the load of traffic at every point along the arch ribs became compression transmitted to the abutments on both shores. The cables that had carried the cantilevered halves through the two construction years went slack and were removed. The arch stood without them. The mathematical calculations had been accurate.

The roadway deck was suspended from the arch by vertical hanger cables after the arch was complete. The deck structure was assembled and connected to the hangers section by section. At mid-span, where the arch crown is at its greatest height above the deck, the hangers were longest. Near the abutments, where the arch springing points were close to deck level, the hangers were short.

The deck was designed as a steel truss structure, stiff enough to distribute roadway loads evenly among the cable attachment points and to resist the aerodynamic forces that harbor winds could generate. Ammann did not design a flexible, lightweight deck of the type that would later tear apart the Tacoma Narrows Bridge in winds of forty-two miles per hour in 1940. The Bayonne deck was stiff. It was designed to remain stable in the wind conditions New York Harbor produces.

It has remained stable. The Bayonne Bridge opened on November 15, 1931. The ceremony was fitting for what had been built. Officials of the Port of New York Authority presided.

The governors of New York and New Jersey were represented. Ammann was present. Speeches were given about the bridge’s importance to the commerce of the Kill Van Kull waterfront and to traffic between New Jersey and Staten Island. A convoy of vehicles crossed the bridge in the official opening procession, while people who had come to watch stood on both shores.

The Kill Van Kull ran beneath the arch with the tidal current that had run there as long as the strait had existed. The ironworkers who built what the dignitaries were crossing were not in Bayonne or Staten Island that morning as a group. They were wherever the next job had taken them. An ironworker who finished his last shift on the deck of the Bayonne Bridge in October 1931 did not stay in the area to attend the opening ceremony in November.

He went where the next steel was being erected. The ceremony was for the people whose names would appear in the commemorative records. The toll at the bridge’s opening was forty cents per private vehicle. The Port of New York Authority collected those tolls and allocated the revenue to repaying the bonds that financed construction and to maintaining the structure.

The bonds were repaid in full as toll revenue accumulated over the following years. The bridge did not fail to generate the revenue expected of it. It served the traffic it was built for. The 1,675-foot record as the longest steel arch in the world—which the bridge acquired simply because the nature of the Kill Van Kull crossing demanded that length—stood for forty-six years until the New River Gorge Bridge in West Virginia opened in 1977 with a main span of 1,710 feet.

By 1977, the Bayonne Bridge had been in service for forty-six years. It had carried more vehicles than the original traffic estimates predicted. It had withstood the weather New York Harbor produces over nearly five decades of winters, ice, winds from the Upper Bay, and the salt air that corrodes steel wherever paint crews have not gotten to it first. The arch was in structural condition befitting a well-maintained bridge of its age.

The maintenance program the port authority operated was continuous, the same kind of ongoing operation any large structure in a marine environment requires. The bridge was not allowed to deteriorate. It was maintained at the level of capacity Ammann designed it to achieve. What it was not designed to accommodate was the problem that emerged in the early years of the twenty-first century.

Container shipping changed the economics of maritime transport in ways the engineers of 1925 could not have foreseen. Container ships grew larger with each decade of the industry’s existence, driven by the principle that a larger ship carrying more containers on the same route is more economical per unit of cargo than a smaller ship. By 2011, the largest container ships in regular service had heights exceeding the Bayonne Bridge’s clearance of 151 feet. They could not pass beneath it.

Ships that could not pass under the bridge could not reach the Port of Newark and Elizabeth, which lies at the end of the Kill Van Kull navigation channel and handles cargo worth billions of dollars annually. A bridge built in 1931 to clearance specifications derived from 1920s ship sizes was limiting the capacity of one of the most important port complexes on the East Coast of the United States. The Port Authority of New York and New Jersey, which had succeeded the Port of New York Authority in operating the bridge, evaluated the options. Replacing the bridge entirely was one option.

Raising the roadway while keeping the existing arch was another. Raising the deck of a bridge of the Bayonne Bridge’s scale had never been done, but it was technically possible. The arch was in excellent structural condition. The abutments had not moved in eighty years.

The steel of the arch ribs had been maintained through continuous inspection and painting, and showed no deterioration that would prevent continued service. What could be changed was the height at which the roadway deck hung below the arch. The hangers connecting the deck to the arch could be replaced with shorter hangers. The deck could be raised.

The approach ramps on both shores, which connected the main span to the road network, would have to be demolished and rebuilt at the new deck level. The target height was 215 feet above mean high water—an increase of 64 feet over the original 151 feet. The Bayonne Bridge Navigational Clearance Program began in 2013. The reconstruction of the approach ramp on the Bayonne shore passed over a residential neighborhood that had grown up around the original approach structure in the eight decades since the bridge opened.

The new approach ramp had to pass over the streets below at the new deck level. On the Staten Island side, connection to the local road network required reconfiguration to suit the new height. Throughout all of this, traffic continued to cross the main span at the original deck level while the ramps were rebuilt from both sides. Then the deck of the main span was raised in sections, with the arch above remaining unchanged the entire time.

New hangers were installed. New connections between the deck and the arch were made by construction workers in 2017 and 2018—work not entirely unlike what the ironworkers did in 1931, fastening connections to arch ribs that those earlier workers had riveted eighty-six years before, at heights above the Kill Van Kull and in its changeable weather. The project was completed in 2019. The clearance now available is 215 feet.

The largest container ships currently in regular service can pass beneath it. The arch has not changed. The riveted steel connections installed by the ironworkers between 1928 and 1931 are still in the ribs. The arch is still in compression.

The abutments that took the thrust of the crown pins when they were driven in October 1931 still carry the thrust of the arch as the loads of ninety-three years of traffic pass across it. If you cross the Bayonne Bridge today, you rise up the approach ramps to a deck 215 feet above the waters of the Kill Van Kull. Entering the main span, the arch ribs curve above you from both sides in the parabolic form Ammann derived from the load requirements and the geometry of the span. The Kill Van Kull lies below you.

The current that has flowed through that strait since the last ice age still runs. Oil tankers and container ships pass beneath the deck thanks to the clearance the raised structure now provides. On a clear day, you can see the Upper Bay to the east, the skyline of Lower Manhattan behind it, and the industrial shore of Newark Bay to the west. The Kill Van Kull is still an industrial waterway.

The nature of the industry has changed over ninety years, but the water still carries the commerce of the port. The arch above your head is the arch riveted by men who worked on sloping steel surfaces at heights above a tidal current during the worst economic depression in American history. The crown of the arch—the point where the two suspended halves of the bridge met and the connecting pins were driven in October 1931—is the highest point of the structure. The men stood there to close the gap and saw the harbor in every direction, then drove the pins and came down, and the temporary cables were released, and the arch stood as the mathematics predicted.

Then they moved on to their next job without ceremony, because there was no ceremony planned for those who drove the crown pins. Othmar Ammann went on designing major bridge structures for thirty-three years after the Bayonne Bridge opened: the Triborough Bridge in 1936, the Bronx–Whitestone Bridge in 1939, the Throgs Neck Bridge in 1961, and the Verrazzano-Narrows Bridge in 1964, which connected Staten Island to Brooklyn across the Narrows and ended the area’s practical isolation from the city of which it had been part for more than a century, and which was at its opening the longest suspension bridge in the world. Ammann died in 1965 at the age of eighty-six, a year after the Verrazzano-Narrows Bridge opened. He had been designing bridges for sixty years.

Every structure he designed remains in service. His name is in the engineering records and on the historical plaques of each of them. The men who riveted the arch ribs of the Bayonne Bridge exist in the payroll records of the American Bridge Company, in the employment files of the Port of New York Authority, and in the accident reports documenting four deaths. They are not in any document a person might find today without deliberately conducting archival research.

The bridge they built has carried traffic across the Kill Van Kull for ninety-three years. It has been raised once, in a process that required workers of a later era to make new connections to the arch ribs that the workers of 1931 built. The rivet heads installed by the riveting gangs between 1928 and 1931 are still in the steel. The arch is still in compression.

The Kill Van Kull is still in operation.