In the summer of 1913, a workman stood on a temporary wooden platform two hundred feet above the floor of Tunkhannock Creek Valley in Wyoming County, Pennsylvania, guiding a concrete bucket suspended from an overhead cable. The cable ran from an aerial tramway strung between towers on the hillside above. The bucket weighed hundreds of pounds when loaded. His job was to receive it at the arch form, open the discharge gate, and direct the concrete into the form while keeping his balance on a platform that was neither level nor flat, two hundred feet above the stream below.

The creek at that depth looked like a line through the hemlock and birch in the valley bottom. The hill above was close enough to see the mixing plant where the concrete came from. Other arch bays stretched in both directions along the valley. Some were complete.

Some were still temporary structures with empty forms. And some, like the one he was working on, were in the process of becoming what they would be for the next hundred years. What he was pouring was concrete. What he was building was the Tunkhannock Viaduct.

When completed in 1915, it would be the largest concrete structure in the world. It would carry the Delaware, Lackawanna and Western Railroad across Tunkhannock Creek Valley on ten elliptical arches, each spanning one hundred eighty feet between abutment faces. The bridge would stretch 2,375 feet from pier to pier, with a maximum height of 240 feet above the valley floor. It still carries trains today.

Norfolk Southern runs it now on the former Lackawanna main line between Scranton and Binghamton. The freight crossing it in the twenty-first century rides on the same concrete those men poured on those platforms in 1912, 1913, and 1914. The man who caught the concrete bucket in the summer of 1913 was Italian. He had come to Wyoming County, Pennsylvania, from somewhere in southern Italy.

Calabria, or Campania, or Sicily, or Basilicata. The province is not recorded in the published engineering records of this bridge. He was one of hundreds of Italian immigrant laborers who worked at the Tunkhannock construction site. His name, if it ever appeared in the surviving construction records at all, appeared only in the context of records kept to track costs, not to track people.

To understand why the Delaware, Lackawanna and Western Railroad built a 240-foot-high, 2,375-foot-long concrete bridge across Tunkhannock Creek in 1912, you have to understand the nature of the Lackawanna main line in 1900 and what the railroad needed it to become. Wyoming County sits in the northeastern corner of Pennsylvania, within the geological province known as the Ridge and Valley Appalachians. The Ridge and Valley province is exactly what its name suggests: parallel ridges of hard sandstone and conglomerate running northeast to southwest, interspersed with valleys of softer shale and limestone, drained by streams that cut through the ridges through water gaps and along the valleys between them. It is winding, repetitive terrain.

A railroad running northwest from Scranton toward Binghamton crosses these ridges and valleys at oblique angles to the structure of the land. It climbs, descends, and climbs again. The Delaware, Lackawanna and Western Railroad was founded in its modern form in the 1850s to do exactly that. Its purpose at founding was to move anthracite coal from the Wyoming Valley coal fields centered around Scranton and Wilkes-Barre, north and east to northeastern coastal markets.

The anthracite from the Wyoming and Lackawanna valleys was the home heating fuel of New York, Philadelphia, and Boston, and the industrial fuel for the iron furnaces and manufacturing plants of the northeastern corridor. It was a dense, high-energy fuel with no close substitute in the domestic market in the nineteenth century. The railroad that controlled the anthracite fields and the routes out of them controlled the fuel supply of the American Northeast. The Lackawanna controlled the route from the Wyoming Valley to the New York and New England markets.

It did so effectively. By the 1880s, the Lackawanna was one of the most profitable railroads in the United States on a per-mile basis. The freight it carried was not general merchandise. It was a single commodity, dense and consistent, with demand that did not fluctuate seasonally except in the expected direction of winter heating requirements, which were large and reliable.

The Lackawanna did not need to build traffic. It needed to move what the mines produced at the lowest possible cost per ton to the coastal ports and consuming markets. The problem with the Lackawanna main line between Scranton and Binghamton in 1900 was the same problem that afflicted most American railroads built in the 1850s with the tools and budget of that decade. The engineers had found a line across difficult terrain that could be built and that locomotives of that time could operate on.

The result was a main line with grades as steep as 1. 5 percent in places, and curves that forced trains to slow down and imposed wear on track and equipment disproportionate to the load being carried. In 1855, this was acceptable. The locomotives of that year were light and the coal trains were short.

What a light locomotive pulling a short train could handle was what the engineers had designed for. By 1900, the locomotives and cars that the Lackawanna’s operating department assigned to the coal service between Scranton and Binghamton had far exceeded the expectations set by the surveys of 1855. Coal trains on this line had become longer and heavier. A grade that a locomotive had once climbed without strain now required two locomotives to pull the heavy coal trains.

The second locomotive was coupled on the rear or pushed from behind, incurring additional costs in fuel, crew time, and extra locomotive miles, which the operating accountants recorded on every train trip. The curve restrictions required speed reductions, increasing running time and occupying the line for longer periods in every schedule. Railroad operating cost accounting in the early twentieth century was an arithmetic that railroad managers performed continuously. Cost per ton-mile, fuel consumption per locomotive mile, crew hours per train trip.

Every item in the operating plant contributed to this figure. A main line with reduced grades and straightened curves achieved a lower cost per ton-mile than one with the grades and curves imposed by the terrain surveys of the 1850s. That reduction multiplied with every train trip on the line, daily, for the remaining life of the main line. The Lackawanna’s chief engineer in the early twentieth century was Lincoln Bush.

Bush was tasked with studying the Scranton-Binghamton corridor for possible realignment. A new line that achieved a sufficient reduction in grades and curves to justify the capital construction cost would yield operating savings that the railroad’s financial officers could calculate against projected traffic over the life of the line. Bush found the route. The route he laid out would reduce the maximum grade in the corridor from 1.

5 percent to 0. 6 percent. It would also eliminate the sharpest curves. And it would shorten the distance between Scranton and Binghamton by eleven miles.

The capital cost of the cutoff project, which Bush estimated at several million dollars, would be recovered through reduced operating costs over a period the Lackawanna’s financial analysis deemed acceptable. The route achieved these results by means that the terrain required. The new line had to stay at ridge level to maintain the reduced grade. Staying at ridge level while crossing Tunkhannock Creek Valley meant building a bridge across the valley at that elevation.

Tunkhannock Creek Valley at the crossing point Bush chose was 240 feet deep and about half a mile wide at the elevation the new line required. It could not be gone around. It could not be descended into and climbed out of without reimposing the grades the cutoff project was designed to eliminate. It had to be crossed.

Crossing it required a bridge 240 feet high and 2,375 feet long. There was also Martins Creek Valley, a few miles to the northeast. The cutoff project ultimately produced two major bridges, the Tunkhannock Viaduct at Nicholson and the Martins Creek Viaduct at Kingsley. Both were concrete arch structures.

Both were designed by Bush’s engineering department. Tunkhannock was the larger and the first. It set the standard for what was possible. The decision to build Tunkhannock in concrete rather than steel was not the obvious choice in 1908, when the project was approved.

American railroad engineering had a default material for large bridge structures in 1908. That material was steel. Steel had been the dominant material for American railroad bridge construction since the 1880s. The Ohio River crossings, the Mississippi River bridges, the great steel truss and cantilever bridges carrying mountain rail lines across valleys at heights comparable to Tunkhannock.

All steel. The Kinzua Bridge in McKean County, Pennsylvania, one of the most prominent high railroad bridges in the northeastern United States, was steel. The engineering firms that designed major railroad bridges in 1908 designed them in steel because steel was their accustomed material and what the industry built. Steel had real advantages.

It could be fabricated off-site in industrial quantities to precise specifications and shipped to the construction site to be assembled by ironworkers whose skills and practices were entrenched across the American railroad system. Its dimensions could be engineered to carry specific loads with calculable safety margins. It had a service record in American railroading stretching back four decades. It also had a track record that Bush and the Lackawanna engineering department had to consider.

Loads on an active railroad main line were not static. They increased as locomotives grew more powerful and as operating economics pushed toward longer, heavier trains. A steel structure designed for the loads of 1908 would carry those loads adequately. As loads increased beyond design limits, the steel members would require reinforcement or replacement.

American railroad history from 1870 to 1908 proved beyond doubt that loads increase. The old camelback bridge the Pennsylvania Railroad replaced at Rockville in 1900 was one example among dozens. Designed for the locomotives of 1877, it was obsolete before it was twenty-five years old, because the locomotives of 1895 weighed twice what the locomotives of 1877 weighed. The Lackawanna was building the Tunkhannock crossing to last.

The operating savings the cutoff route was designed to achieve depended on the infrastructure remaining in service for the expected life of the main line. A structure requiring reconstruction in the foreseeable future cost twice: once to build and once to rebuild, and imposed disruption and capital expense for rebuilding on an unpredictable schedule. Concrete in compression had properties that distinguished it from steel in a way relevant to this calculation. An arch transfers load through compression.

Concrete is strong in compression. It is the material’s strong mode, the mode in which it is not stressed the way steel is stressed under tension and bending in repeated loading. Portland cement concrete gains compressive strength over time as the cement hydrate bonds continue to develop. A concrete arch built to proper specifications and loaded within those specifications becomes gradually stronger over the decades following its construction.

The failure mode of a concrete arch overloaded beyond capacity is visible before it becomes catastrophic. Cracking precedes collapse. That cracking is observable during routine inspections. An arch approaching its load limit announces its condition.

A steel structure approaching fatigue failure may not announce itself as clearly. Bush performed the same fundamental calculations the Pennsylvania Railroad’s engineering department had performed at Rockville in 1899. What material, built to what specifications, would carry railroad traffic the longest without requiring reconstruction? At Rockville, the answer had been cut stone masonry.

At Tunkhannock in 1908, the answer was Portland cement concrete. Stone construction required quarried stone cut and dressed to precise geometry by skilled stonecutters, and the labor cost of that dressing had risen between 1899 and 1908. Concrete could be mixed on site from Portland cement and local aggregate, poured into wooden forms, and achieve the compressive strength the design required without the quarrying and dressing operations stone construction demanded. The material decision was a logistics decision too.

The Lackawanna main line ran right along the construction corridor. Portland cement arrived by train from the Lehigh Valley cement plants, which were and remain one of the principal Portland cement manufacturing regions in the United States. The aggregate came from local quarries in Wyoming County and from material excavated during the foundation work of the piers and abutments. Water came from the creek below and from the supply system developed as part of the construction process.

The railroad the bridge was being built to serve delivered the materials the bridge required. The engineering department specified a hollow arch construction. Above the arch crowns, side walls would rise on each side with openings between transverse walls, a cellular structure that reduced dead weight while providing the structural depth the track and roadbed required. The total concrete was approximately 167,000 cubic yards.

At the mixing rates achievable with the equipment available to the contractor, producing and placing that quantity over a three-year construction schedule meant operating a concrete production plant continuously across three building seasons. The Lackawanna awarded the construction contract to Degnon-McLean, a heavy construction contractor with experience in large-scale concrete work. The contract set a completion date. The completion date set the construction schedule.

The construction schedule set how much work had to be accomplished in each season. The first task for Degnon-McLean at the site was not concrete. It was lumber. The arch forms had to be built before any concrete could be poured.

The formwork problem at Tunkhannock was unlike anything American bridge builders had faced in 1912. At the Rockville Bridge in 1900, the arch form had spanned seventy feet and was supported from the bed of a relatively shallow river. It was a massive structure by ordinary standards. At Tunkhannock, the form had to span 180 feet and be supported from the floor of a valley 200 feet below the arch.

The timber structure required to support a 180-foot-span concrete arch ring while the concrete cured without settlement or instability was the largest temporary structure ever built in the United States up to that date. The forms were designed as trestle bents, heavy timber frames rising from foundations in the valley floor, braced and guyed to resist wind loads and the asymmetrical loads of concrete being poured progressively around the arch. The bents were spaced along the arch span and carried the arch form at the top. The timber came from the forests of the northern Pennsylvania plateau, available in the quantities required because the plateau had been heavily logged for decades and the reclaimed lumber trade was active.

The bridge carpenters who built these temporary structures were not ordinary carpenters. The usual experience of a bridge carpenter in 1912 included temporary structures of modest height over water or on level ground. The men who built the Tunkhannock forms were working on structures with no direct precedent in the knowledge of their trade. The principles were the same: bent spacing, bracing geometry, load distribution through the timber frame to the foundations below.

The scale was entirely different. The form of each arch was a separate structure. There were ten arches. The construction sequence required building each form, using it, then striking it from the completed arch and re-erecting it in the next opening between piers.

The cost of the timber and labor was consumed over ten uses. Each use required the structure to perform correctly, to carry the concrete load without movement during the pour, to hold position while the concrete cured, and to separate cleanly from the arch when the supports were removed. Striking the forms from a concrete arch is a different test moment from striking them from a stone arch. A stone arch holds together because the geometry of its stones balances.

The wedge-shaped stones transmit load through contact and compression at the joint surfaces. The arch becomes structurally complete the moment the keystone is placed. A concrete arch is a single mass, but it does not gain its strength instantly. It gains compressive strength over time as the cement hydrates, at a rate dependent on temperature, humidity, and mix composition.

The supporting forms cannot be removed until the concrete has reached the compressive strength the engineering specifications require. At Tunkhannock, during the winter construction periods, fresh concrete in the arch forms gained strength slowly. The construction seasons at Tunkhannock were governed on one side by the chemistry of concrete in winter, and on the other by the demands of the construction program. The Lackawanna’s operating schedule set the delivery date.

The delivery date set how much slowness of cure the seasons could absorb before the schedule failed. The winter of 1912 to 1913 was a Pennsylvania winter in Ridge and Valley country, where freeze and thaw begin in November and run through March in most years. Fresh concrete poured in November and cured through December gained compressive strength at a fraction of the rate of a September pour. Protecting new concrete from frost required enclosing the work, maintaining fires at the construction site, and monitoring temperatures inside the forms.

This work moved slower and required more management than summer pouring. The summer of 1913 compensated in a different direction. Ridge and valley terrain traps heat the way enclosed valleys everywhere do. The ridges hold the air in the valley bottom.

In July, the valley bottom is warmer than the surrounding country by the margin imposed by elevation and reduced airflow, which in northeastern Pennsylvania in July is not a small margin. The workman standing on a support platform in direct sun 200 feet above the valley floor in July had no artificial shade, and faced the full radiative load of a Pennsylvania midsummer from above and reflected from the concrete forms he was working on. The aerial tramway operated continuously through working hours. Loaded buckets moved from the mixing plant on the hill to the arch forms below via the cable.

The men on the support platforms received the buckets, opened the gates, directed the concrete into the forms, and compacted it by hand with tools that worked the aggregate into the spaces not filled by the mix. The pace of work was set by the production capacity of the plant and the carrying capacity of the aerial tramway. It was not set by the wishes of the men working at the forms. The workforce that built the Tunkhannock Viaduct was Italian.

Italian immigration to the United States in the first decade of the twentieth century was approaching its historical peak. Between 1900 and 1914, about three million Italians arrived in the United States. The vast majority came from southern Italy, from the provinces of Calabria, Campania, Basilicata, Abruzzo, Molise, and Sicily. They were not coming from regions of prosperity experiencing a temporary disruption.

They were coming from a region where subsistence agriculture had been the economic mainstay for generations, and where a succession of overlapping disasters had reduced the margin to below subsistence. The phylloxera blight that destroyed the vineyards of Campania, Calabria, and Sicily during the 1880s eliminated the one export crop that had provided cash income for smallholding families throughout the Mezzogiorno. Land consolidation moved holdings from small proprietors to large owners in the decades following Italian unification, reducing the class of men who worked their own land and increasing the class of men who worked the land of others for wages that could not support a family in a bad year and barely supported one in a good year. The unified Italian state integrated the south economically, which meant extracting tax revenue and military conscription from it without building the industrial employment or transport infrastructure that economic integration brought to the northern regions.

A man who could not feed his family in Calabria in 1905 weighed his options. Internal migration to the industrial cities of Turin or Milan was possible, and some took it. Migration to Argentina or Brazil was possible, and many went there. Migration to the United States was possible, and the wages the United States paid construction workers in 1905 were a figure circulated through Mezzogiorno villages via letters from the men who had gone before and through the networks of labor contractors who recruited there.

The wages were not high by American standards. By the standards of annual income for a day laborer in Calabria, they represented multiples that made the cost of crossing the Atlantic, leaving the family, and entering a country whose language and legal system were entirely alien a rational calculation. Enough to survive on, and enough to send something home, but not enough to save in any way that achieved economic security on a foreseeable horizon. This surplus above subsistence was the incentive that drove men across oceans.

It had driven Irish men in the 1830s. It was driving Italian men in the 1890s and early 1900s. The economic logic was the same. The men who came to Wyoming County, Pennsylvania, in 1912 to work on the Tunkhannock construction arrived through the padrone system.

The padrone was an Italian labor contractor, usually a man from the same region of Italy as the workers he organized, who had established working relationships with American construction firms and could deliver a workforce of a specified size to a specified location at a price the construction company’s budget could bear. The padrone recruited workers in Italy and in the Italian neighborhoods of Atlantic port cities where earlier immigrants had concentrated. He arranged transport to the work site. He maintained the housing camps near the construction site where the workers lived for the duration of the project.

He ran the company store where the workers bought food, tools, and living supplies at a construction camp in Tunkhannock Creek Valley. He negotiated the labor contract with the construction company at a specified rate per man per day. He paid the workers what remained after deducting administration fees, camp housing charges, and his profit margin on the goods he sold at the store. The net wage that reached the Italian worker at the Tunkhannock site was what remained of the market rate after the middleman took his cut.

The market rate for Italian construction laborers in Pennsylvania in 1912 ranged from $1. 50 to $1. 75 per day. White American workers doing similar work in the same class of projects earned $2.

00 or more per day. This disparity was not hidden. It was the wage structure in operation in the American construction labor market of 1912, entrenched by custom and sustained because the parties capable of changing it saw no reason to. The Italian worker’s actual wage after padrone deductions was what remained of the wage.

This was the amount he sent to his family in Calabria, or saved if saving was possible from what remained of the net wage. By 1912, Progressive-era labor reformers had given the padrone system a name. The federal Bureau of Immigration had documented it. A Pennsylvania legislative commission had discussed regulating it.

The system continued to operate on major construction projects across the northeastern United States because the construction firms that needed mobile, rapid labor, and the contractors who supplied it, were in a position to continue it. The Italian workers it harmed were not in a position to change it. They were not citizens. They were not organized.

They did not vote in Wyoming County elections. They worked on temporary platforms two hundred feet above Tunkhannock Creek. The construction company payroll records documented the Italian labor force at the level those records required. The padrone received a lump sum for the labor supplied at the agreed rate.

Individual workers appear in the surviving construction records at the work-group level, and in some cases by name in the daily time sheets kept by the foreman. Many appear as aggregate numbers: a certain number of men for a certain number of days at the applicable rate, recorded against a payment to the contractor. The workers who fell below the gang-boss level in the Italian work crews appear in those records at the level required for cost tracking. That level was not the level required for tracking people.

The work done by the Italian workers at the Tunkhannock site was classified as unskilled labor in the employment records of 1912. That classification set the wage. It did not describe the work accurately. A man working on a temporary platform two hundred feet above a Pennsylvania valley understood the properties of what he was working with.

He understood the behavior of a loaded concrete bucket swinging on a cable from an aerial car. The arc it took, the correction required to land it in the form without letting it swing wide, the weight of the load, the radius of the swing as the cable slackened. He understood the surface he stood on, which was not designed for comfort and was not level. He was aware of the distance to the valley floor.

He had known it since the first day he climbed to that height, and it did not become abstract through familiarity. The accident records of the Tunkhannock construction documented injuries and deaths at the level Pennsylvania law required of construction companies in 1912. Pennsylvania’s workers’ compensation law was not yet in effect. It was enacted in 1915, the same year the bridge was completed.

The legal framework governing employer liability for construction injuries during the Tunkhannock construction was the common law of contributory negligence, under which a worker found to have contributed in any way to his own injury could claim nothing from his employer. A man who fell from a temporary platform two hundred feet above a valley was considered, under the prevailing legal interpretation of the time, to have assumed the risk of the height when he accepted the job. The men who worked in the Portland cement mixing plant on the hills above the valley worked in cement dust. Portland cement is strongly alkaline.

It reacts with moisture in the respiratory tract, on the surface of the eyes, and on the skin of the men who worked with it constantly. The chronic occupational exposure in the mixing and handling environment of a large concrete construction project produced respiratory and dermal conditions that industrial medicine in 1912 was beginning to characterize systematically, and that later decades documented with greater precision. The men in the plant knew what the work was doing to them. They knew it from experience, not from medical literature.

They kept working because the wage the work paid was the wage their circumstances required. The Pennsylvania winter that slowed the curing of concrete did not slow anything else in the construction process. The pier caps still had to be placed above the valley walls in winter. The centering timbers still had to be fabricated and erected.

The men who did this work in Wyoming County in January and February 1913 did it in the conditions Wyoming County in January and February created. The construction camps that the padrone maintained for the Italian workforce near the work site were the housing a contractor provided a temporary workforce in 1912. Adequate to keep the men effective for the work. They were not designed to withstand a Pennsylvania winter the way permanent structures were.

The first arch on the Tunkhannock Viaduct had its falsework removed to bear its own weight for the first time in 1913. The carpenter crew released the wedges and moved the bracing frame away from the underside of the arch. The arch held. The concrete poured in stages over weeks, cured amid the temperature swings of a Pennsylvania autumn and winter, had reached the strength the engineering required.

It maintained the geometry the forms had given it and carried the weight the falsework had been holding. The falsework was moved to the next opening between the piers. The carpenters rebuilt it. The concrete crews poured the next arch.

Ten times, across 2,375 feet of Tunkhannock Creek Valley. The piers were built, the forms were loaded, the concrete cured, the forms were struck, and the arch carried its own weight. The engineering analysis was validated ten times. The arch rings held.

The hollow spandrel walls above them held. The pier footings set into the sandstone and rock of the valley walls at the depths the excavation reached did not settle. The Tunkhannock Viaduct was completed and opened to Lackawanna train traffic in November 1915. The first trains to cross it on the new line traveled on grades the old main line through the valley had not provided.

The 0. 6 percent maximum that Lincoln Bush’s surveys had set became the grade the locomotives faced from Scranton to Binghamton. The coal trains that had required two locomotives to climb the 1. 5 percent grades of the old line no longer needed them on the new line.

The operating cost advantage Bush had calculated in the early twentieth century became real in every train movement on the new line since November 1915. What the Tunkhannock Viaduct was asked to carry in the decades after 1915 was the development of the Lackawanna’s motive power through the entire steam era and into the diesel transition. The Pacific passenger locomotives the Lackawanna used in its New York-Chicago service during the twenties and thirties crossed the bridge because it was the main line. The Pacifics of class L and the later steam locomotives assigned to heavy coal trains crossed the bridge because the coal was still being moved.

The Mikados and Consolidations that handled most of the freight tonnage through the thirties and forties crossed it the same way. The bridge was there, and the main line ran over it. Anything the railroad sent over the main line crossed over those arches. The steam-to-diesel transition of the fifties brought locomotives that imposed their loads differently, without the reciprocating piston motion and valve gear that had generated dynamic forces on track and structure added to the static weight.

The diesel locomotives ran across the Tunkhannock arches without that additional dynamic component. And the bridge carried the trains as it had carried everything before. The Lackawanna merged with the Erie Railroad in 1960 to form the Erie Lackawanna Railway. The railroad that had justified the cutoff investment in 1908 and opened the line in 1915 ceased to exist as an independent entity forty-five years after the completion of its largest construction project.

Erie Lackawanna was conveyed into Conrail in 1976 following the Penn Central bankruptcy, then the largest institutional collapse in American history, which brought down Erie Lackawanna along with the Pennsylvania Railroad’s successor and numerous other northeastern carriers. Conrail operated the former Lackawanna main line across the Tunkhannock Viaduct from 1976 until 1999. Norfolk Southern acquired the Conrail routes and operates them today. The railroad crossing the Tunkhannock Viaduct daily is the legal heir through three generations of mergers and bankruptcies of the Delaware, Lackawanna and Western Railroad whose route Lincoln Bush surveyed in the early twentieth century.

The bridge those men designed and the Italian laborers built in 1912, 1913, and 1914 is still on the main line. The Norfolk Southern freight crossing it today is the freight of the northeastern industrial corridor the Lackawanna system was built to move. Coal, shipping containers, and mixed merchandise moving between the industrial cities of the east and the interior. If you drive to Nicholson, Pennsylvania, and find the right vantage point in the valley bottom below the bridge, you can see all ten arches in one view.

The concrete has weathered the way concrete weathers over 110 years. The surface has opened slightly where the cement paste has eroded. Mineral stains trace drainage paths down the pier faces. The aggregate is visible in places where exposure has revealed it.

The underlying geometry has not changed. The curves of the arches are the curves Lincoln Bush’s engineers calculated in 1908. The pier faces are the ones Degnon-McLean’s carpenters formed in 1912 and 1913. A Norfolk Southern freight train will give you enough audible warning to find the bridge before it crosses.

The sound comes from the south and deepens as the train approaches the valley. Then the bridge absorbs the crossing, locomotive and train behind it, hundreds of tons at track speed across 2,375 feet of concrete arch. The crossing takes about ninety seconds. The arches do not respond visibly.

The piers do not move. The concrete those Italian workmen placed in those forms during the summers and winters of 1913 and 1914 carries the load of modern freight trains exactly as it has carried every train the successive owners of the main line have sent across it since November 1915. There is a historical marker near the Tunkhannock Viaduct in Nicholson. The marker identifies the bridge’s structure, dimensions, and completion date, and describes it as the largest concrete structure in the world when completed.

The name of Lincoln Bush appears in the engineering references on the bridge. The name of the Delaware, Lackawanna and Western Railroad appears on the marker. Degnon-McLean appears in the construction records at the level contract documentation required. The Italian workers who caught the concrete buckets on the temporary construction platforms two hundred feet above Tunkhannock Creek Valley in the summer of 1913 are not on the marker.

The men who built and struck the wooden forms ten times across the ten openings, the men who worked in the Portland cement plant amid the alkaline dust on the hill, the men who poured the concrete into the forms through Pennsylvania winters while it cured according to the temperatures, are in the construction company records at the level those records required. The construction records of the Tunkhannock Viaduct, the engineering drawings, the cost accounts, the contractor’s labor records, are distributed across several archival repositories. Whether the daily time sheets at the work-group level, and the names of individuals under the foreman in the Italian work crews, still exist in those repositories and at the level of detail the original recording may have captured, is a question the published engineering history of the bridge answers incompletely. The engineering drawings survive in good condition.

The cost accounts survive as the financial record-keeping of 1912 required. The accident records survive at the level Pennsylvania law in 1912 required. The men who executed those engineering drawings at those heights, through Pennsylvania winters and summers, for wages administered by the padrone system and recorded in the construction company’s labor accounts in aggregate, exist in those records as a material cost only. The concrete remains.

The arches are sound. The piers are solid. The engineers who designed the structure are in the records. The contractor is in the records.

The workers who built it are in the records as the cost of their aggregate labor. The Tunkhannock Viaduct remains the largest concrete railroad arch bridge in the United States. It was built once. That was the point.

The men who built it are not on the marker. The bridge is what is there.