How America Built Wooden Trestles 200 Feet High Without Cranes

Ajouté : 2026-05-24

[00:00:00]a logging railroad in the steep country of the Pacific Northwest or the redwood canyons of California or the Appalachian Highlands of West Virginia and Pennsylvania almost always had to cross several deep ravines and canyons in the course of its run from the cutting area down to the mill. The standard solution in the period from about 1880 to 1940 was a wooden trestle built entirely of timber, often more than 100 ft tall, sometimes more than 200 ft tall, supporting locomotives weighing 50 or 60 tons and loaded log cars weighing far more than that. These trestles were built by crews of men using almost no mechanical lifting equipment beyond the simple wooden derks and gin poles that the construction crews built on site.

[00:00:52]There were no truckmounted cranes. There were no tower cranes. The big self-propelled construction cranes that we associate with modern bridge building did not exist in any useful form during most of the period when the wooden trestles were going up. The men who built these structures used hand tools, animal power, gravity, and an enormous quantity of timber, and they put together bridges that would have been considered impressive even by the standards of professional bridge engineering. The basic logging trestle was a bent construction wooden bridge. A bent is a vertical frame made up of several vertical posts connected by horizontal and diagonal bracing that supports the bridge deck above it. A typical logging trestle consisted of a long series of bents spaced perhaps 15 ft apart. Each bent rising from the floor of the canyon up to the level of the rail deck. The bents were connected to each other by horizontal stringers and longitudinal bracing, forming a structure that resembled in section a series of wooden ladders standing side by side with the rungs aligned to form a continuous deck on top. The rails sat on top of the deck, supported by ties that ran across the trestle. The whole structure was held together by iron bolts, drift pins, and various pieces of forged hardware. But the bulk of the material was wood. The choice of wood as the primary material reflected the realities of where these bridges had to be built. A logging operation worked in a forest where wood was the cheapest and most abundant local material. The cost of bringing in steel or iron in the quantities that a long bridge would require was prohibitive. In most cases, steel had to come in by rail from distant mills on grades that the logging railroad itself was not yet capable of climbing. Wood could be cut on site from the trees that surrounded the construction location. A skilled crew could harvest the timber from within a few hundred yards of the bridge site, mill it as needed, and have it ready for use within days of cutting. The structural performance of wood, while inferior to steel in most respects, was adequate for the loads that logging trains imposed, provided that the bridge was built with appropriate oversizing of the members and was inspected and maintained regularly. The largest of the wooden logging trestles reached impressive sizes. The Big Creek Trestle on the Westside Lumber Company line in California, completed around 1900, was approximately 1,200 ft long and 120 ft tall at its highest point. The Pacific Lumber Company's main line out of Scotia, California, crossed several substantial canyons on trestles ranging from 60 to 180 ft in height. The HCH HCHE railroad built by the city of San Francisco in the early 1910s to supply construction materials for the HCH HCH reservoir project used several large wooden trestles in the upper tower river Canyon with the largest exceeding 200 ft in height. The trestles built by the Cass Logging Railroad in West Virginia included several that approached or exceeded 200 ft. The Tyesta Valley Railway in Pennsylvania had trestles up to 150 ft tall. The various logging operations in the Aderondax and northern New England had smaller but still substantial trestles. The construction methods used to build these structures varied somewhat from operation to operation, but followed a generally consistent pattern. The first step was to clear and level the ground at each bent location, removing trees and stumps and leveling the soil so that the foundation timbers could be laid flat.

[00:04:53]The foundations themselves were usually heavy. Mudsills, that is large horizontal timbers laid directly on the ground, sometimes set in shallow trenches lined with crushed rock or wooden cribbing for drainage. The mudsills distributed the load of the bent over a wide enough area of soil that the bent would not settle unevenly into the ground. Once the mudsills were in place, the actual bent was assembled.

[00:05:20]The vertical posts of the bent, usually four or six in number depending on the height and the load, were cut to length and prepared with the necessary mortises and tenins to receive the cross bracing.

[00:05:33]The posts were laid out flat on the ground in the configuration in which they would eventually stand and the cross bracing was bolted or pinned to them in this flat configuration. When the bent was fully assembled flat, the entire structure was raised to vertical by means of chin poles, block and tackle and the muscular effort of the construction crew. The raising operation was the most dangerous phase of bent construction. A bent that was being raised had to be controlled carefully to prevent it from going past vertical and falling over backwards. The crew used guy ropes attached to the top of the bent anchored to dead men or to existing structures at a distance to control the angle of the bent as it came up. A failure of a guy rope or a miscalculation in the angle of pull could allow the bent to fall with potentially fatal consequences for any crew members working near its base.

[00:06:34]The gin poles used in the raising operation were simple in design. A ginpole is a single vertical timber set in a shallow base supported by guy ropes anchored to the surrounding ground or to existing structures. The top of the ginpole carries a block and tackle which is used to lift loads. A small gin pole might be 20 ft tall and capable of lifting a few hundred lb. A large gin pole of the kind used for major trestle construction might be 60 ft tall fabricated from a single large fur or pine and capable of lifting several tons. The gin pole had to be set up at each new bent location used for the raising of that bent, then taken down, moved to the next location, and set up again. The setup and breakdown of the ginpole was itself a substantial operation that consumed significant time on each bent. Once a bent was standing in its proper location, it was secured to the mudsills with heavy iron bolts and to its neighboring bents with horizontal stringers that ran along the upper part of the trestle. The stringers were lifted into place by the same ginpole system supplemented by smaller derks and hand operated winches positioned along the partially built structure. As the trestle grew, the construction crew worked from the top of the completed sections, lifting new materials up from the canyon floor with progressively more capable lifting arrangements. By the time a long high trestle was nearing completion, the lifting system might involve multiple gin poles working in sequence, plus several block and tackle arrangements, plus the use of teams of horses or oxen pulling the lifting lines at the lower ends. The horse and ox teams played a substantial role in the construction. A horse pulling on the lifting line of a block and tackle could provide significantly more sustained power than a team of men on the same line. The construction camps typically maintained several teams for this purpose with the animals worked in shifts and rested between heavy lifts. The animals were stabled in temporary camps near the construction sites and were moved as the work advanced.

[00:08:52]The teamsters who handled the animals were a specific class of skilled worker with responsibilities that included caring for the animals, training them to respond to the construction crews commands, and managing the rigging and the lifting lines that the animals worked. The labor force on a major trestle construction job was substantial. A trestle of any significant size required between 50 and 200 men depending on the scale and the desired pace of completion. The crew was organized into specialized groups. The foundation crew prepared the bent locations and laid the mudsills. The framing crew cut the timbers and assembled the bents on the ground. The raising crew managed the gin poles and the lifting operations. The hardware crew installed the bolts, drift pins, and other iron fittings. The bridge carpenters laid the deck and installed the rails. Above all of these specialized groups was the bridge foreman who coordinated the work and who carried responsibility for the schedule and the quality of construction. A good bridge foreman was a senior man, often with 20 or more years of experience in heavy timber construction, and he was paid accordingly. The unskilled laborers on a construction crew might earn $2 a day. The skilled framers and carpenters might earn $3 or $4. The foreman might earn $6 or $8 a day, plus expenses. The danger of the work was substantial. The fatality rate on major trestle construction projects was probably comparable to that on contemporary railroad construction in mountain country which is to say roughly one death per mile of completed bridge for the largest and most difficult projects.

[00:10:42]The deaths came from a variety of causes falls from the partially completed structure were the most common cause of fatality. A worker who slipped from the top of a 100ft trestle was almost certain to die from the impact. Falls were sometimes the result of equipment failures, but more often they were the result of momentary inattention, fatigue, or weather conditions that made the work surfaces slippery. Crushing injuries were the second major cause of fatal accidents. A timber that slipped from its rigging or a bent that fell during the raising operation could crush a man who was caught in the wrong position. Equipment failures, particularly broken rigging and snapped guy ropes, killed a smaller but still significant number of men. A rope that broke under tension would whip back through the construction area and a man struck by a moving rope or by the piece of hardware at its end could be killed instantly.

[00:11:42]The 1908 collapse of the Pacific Lumber Company's Larabe Creek Trestle during construction killed three workers and injured several others when a partially completed section of the trestle gave way under the load of a piece of construction equipment that was being moved into position. The cause of the collapse was determined to be inadequate bracing of the new section, which had been assumed to be temporarily supported by its connections to the completed sections behind it. The bracing failed when the construction equipment loaded one of the new bents from an unexpected direction. The investigation that followed led to changes in the company's construction procedures with additional emphasis on temporary bracing during the active construction period. The 1912 collapse of a Cass Railroad trestle during construction in West Virginia killed two men when a poorly anchored ginpole tipped over during a lifting operation, dropping a substantial load of timbers onto the construction crew below. The men killed were both relatively young workers. Neither of them experienced bridge carpenters who had been assigned to handle materials at the base of the trestle. The investigation that followed found that the ginpole had been set up by a less experienced foreman who had failed to provide adequate anchoring for the guy ropes. The maintenance of completed trestles was an ongoing requirement throughout their working lives. Wood in outdoor exposure decays, particularly at the points where it is in contact with the ground or with other wood. The mud sills of a bent sitting on or near the ground were particularly vulnerable to rot. The connections between members where water could collect were also susceptible. A trestle that was not properly maintained could fail dramatically with consequences that included the loss of the bridge, the loss of the rolling stock on the bridge at the time, and the loss of any crew members involved in the failure. The maintenance work was carried out by specialized bridge crews who traveled the railroad system on regular schedules, inspecting and repairing the trestles. A typical maintenance crew might consist of four or six men with a bridge foreman and several carpenters.

[00:14:07]The crew would arrive at a trestle set up a temporary camp nearby and spend several days or weeks inspecting and repairing the structure. The inspection process involved climbing over the entire trestle, examining each member for signs of rot, loose hardware, or other damage. Members that were found to be deteriorating were either reinforced or replaced. Hardware that was loose was tightened or replaced. The completed inspection was documented in a written report that was filed with the railroads engineering office. The cost of maintaining a major trestle over its working life was substantial. A large trestle might require replacement of major members every 15 or 20 years.

[00:14:54]Smaller members and hardware required more frequent replacement. The total maintenance cost over the working life of a trestle could exceed the original construction cost by a factor of two or three. As steel bridges became more economically competitive in the early 20th century and as the working life of original wooden trestles came to an end, many operations chose to replace their wooden bridges with steel structures rather than continue to invest in the maintenance of the wooden originals. The replacement was generally done in place with the new steel bridge built around the old wooden one and the wooden bridge then removed. Fire was a particular hazard for wooden trestles. A trestle that caught fire could burn out completely in a few hours, leaving nothing but the iron hardware and the ash. The fire risk came from several sources. Sparks from passing locomotives, particularly from wood burning or coal burning engines, could ignite dry timber in the trestle.

[00:15:57]Wildfires in the surrounding forest could spread to the trestle. Lightning strikes on the highest points of the trestle could start fires. Once a trestle fire started, it was generally difficult to extinguish. The structure was made entirely of wood, often dry and creassoted or otherwise treated with preservatives that contained flammable components. Water was usually not available in any quantity at the trestle locations. By the time a fire crew could reach the burning trestle, the structure was usually beyond saving. The 1922 fire on the Pacific Lumber Company's mainline, which destroyed the Larabe Creek trestle, was caused by sparks from a passing locomotive on a hot summer day. The trestle had been in service for 14 years. Its replacement cost the company over $100,000 in 1922 currency and shut down the operation for several months while the new bridge was being built. The replacement bridge was a combined wood and steel structure with steel main members and wooden decking which was somewhat more fireresistant than the original. The 1934 fire on a Cass Railroad trestle in West Virginia destroyed a major bridge that had been in service since 1909.

[00:17:21]The fire was apparently started by sparks from a passing locomotive. The trestle burned out in about 4 hours with the structure collapsing into the canyon below as the fire weakened the lower members. No one was killed in the fire because the trestle had already been crossed by the train that triggered the fire and the train crew was several miles away by the time the fire was discovered. The replacement was again a combined wood and steel structure. The wooden trestles that survived in service into the second half of the 20th century are now mostly gone. A few have been preserved as historical curiosities. The Cass Scenic Railroad in West Virginia includes several wooden trestles that have been maintained and rebuilt to support the modern tourist operation.

[00:18:09]The HCH Hchi Railroad route is largely abandoned with most of its trestles long since collapsed into the canyons of the upper two alumni. The Pacific Lumber Company's main line was rebuilt with concrete and steel structures in the 1960s and 1970s. The Westside Lumber Company Trestles were mostly abandoned and removed after the operation closed in 1962. A few specific operations deserve a fuller description because they illustrate the scale and the engineering achievement of the wooden trestle era. The Westside Lumber Company based at Toum in California operated one of the more impressive wooden trestle networks in the western United States.

[00:18:54]The company's main line ran from Tu Alumni up the Stannislaus River drainage to various cutting areas in the Sierra Nevada with branches extending to specific timber blocks. The total length of the system was about 70 mi with elevation gains exceeding 3,000 ft from the lower terminus to the highest cutting areas. The line crossed numerous canyons and ravines requiring more than a 100 trestles of varying sizes. The largest of the trestles, the big creek structure mentioned earlier, was about 1,200 ft long. Several other westside trestles exceeded 100 ft in height, including bridges across Beaver Creek and the middle fork of the Stannislaus.

[00:19:39]The company operated for Shea locomotives in regular service, plus a number of smaller industrial engines for specific tasks. The fatality record of the westside operation is documented in the two alumni county newspapers and in the Sierra Railway archives, which preserved many of the Westside records after the operation closed. Between 1898 and 1962, the line recorded at least 21 fatal accidents directly involving the trestle network or rail operations.

[00:20:12]The causes included runaway logs that crossed the trestle deck and struck workers, men falling from the trestles during maintenance work, derailments on the trestle approaches, and one notable 1923 incident in which a Sha locomotive went off the rails on a curving trestle near the upper end of the line, dropping 80 ft to the canyon floor and killing the engineer and firemen. The HCH HCHE railroad mentioned briefly above deserves a fuller account because of the scale and the unusual purpose of the operation. The city of San Francisco needed to build a reservoir in the upper two Alumni River Canyon in what is now the HCH Hchi Valley of Yusede National Park to supply municipal water. The reservoir project required moving enormous quantities of construction materials, including cement, steel, and supplies, into a remote and roadless canyon. The city built a private railroad, the HCH HCHE railroad, for the specific purpose of supporting the construction. The line ran from a connection with the Sierra Railway at HCH HCHE junction up to the dam site at Oonessy Dam, a distance of about 68 mi.

[00:21:28]The route crossed the rough country of the lower Tuolumn Canyon and required several major trestles including the Lumston Bridge over the Tuolumn River at a point where the canyon was particularly deep. The Lumston Bridge was approximately 750 ft long and over 200 ft tall at its highest point, making it one of the tallest wooden trestles ever built in California. Construction of the railroad began in 1915 and was completed in 1918. The line operated for about 14 years supporting the construction of Osha Dam and the associated water infrastructure. After the dam was completed in 1923 and the supporting facilities in 1934, the railroad was largely abandoned. The trestles, including the Lumston Bridge, were partly dismantled for salvage and partly left to rot. The Lumston site can be visited today with some foundation stones and a few rotted timbers remaining as evidence of what was there.

[00:22:34]The labor force on the hetche construction was unusual in its composition. The city of San Francisco contracted with various private firms for the work and the workforce included a high proportion of immigrants from southern and eastern Europe particularly Italians, Greeks and Yugoslavs supplemented by Mexican workers brought in for specific tasks. The bridge construction crews in particular included experienced bridge builders from the conventional railroad industry, supplemented by men from the regional logging operations who knew wooden trestle construction.

[00:23:12]The combined workforce assembled the largest and most complex wooden trestles ever built in the California Sierra.

[00:23:19]working under conditions that involved long stretches of remote location, harsh weather, and difficult access. The fatality record from the construction includes at least nine men killed directly in trestle work with additional deaths from other causes that brought the total construction fatality count to over 30 over the four years of work. The Cass Railroad operation in West Virginia mentioned earlier is the best preserved of the major wooden trestle systems still accessible to the public. The Cass Scenic Railroad State Park operated by the West Virginia State Government as a tourist attraction maintains several of the original wooden trestles in working condition. The maintenance is continuous and expensive with major timber replacement carried out on a rolling schedule.

[00:24:11]A visitor to Cass today can ride a Shea locomotive across wooden trestles built on the original plans of the mower lumber company with the structures looking much as they did during the active commercial operation.

[00:24:26]The experience is genuine, although the trestles themselves contain very little of their original timber, most of it having been replaced over the decades.

[00:24:36]The state park staff includes several skilled timber framers and bridge carpenters who maintain the structures and the operation provides one of the few remaining environments in which the traditional wooden trestle construction techniques are still actively practiced.

[00:24:52]The Goat Canyon Trestle in San Diego County, California, is sometimes cited as the longest curved wooden trestle in the world. Although it was built for a passenger railroad rather than a logging operation. Completed in 1933 by the San Diego and Arizona Eastern Railway, it is approximately 750 ft long and 180 ft tall at its highest point. The structure has been out of service for several decades, but is still standing, providing one of the better surviving examples of the wooden trestle construction techniques that were also used in logging applications. The trestle is on private property and is not generally accessible to visitors, but it has been photographed and documented extensively. The Kinsa Vioaduct in Pennsylvania was originally an iron structure built in 1882.

[00:25:47]401 ft long. While not technically a wooden trestle, the Kinsa used construction techniques and methods that had been developed for wooden trestle construction scaled up for the iron version. The original Kinsua was rebuilt in steel in 1900 and operated for the next century before being partially destroyed by a tornado in 2003.

[00:26:11]The surviving sections are now part of a state park in Pennsylvania. The men who built the great wooden trestles are mostly forgotten. The bridge foremen who supervised the work occasionally appear in company records and local histories.

[00:26:28]The Pacific Lumber Company employed several notable bridge foremen over the decades, including a man named John Padrini, who was responsible for several of the major Larabe Creek crossings.

[00:26:40]Padrini gave interviews in his later years to oral historians at Humboldt State University and his accounts of the construction methods are among the better firsthand sources for the practice. The men who worked under Padrini and the other foremen are largely anonymous identified only in the occasional injury report or fatality notice in the local press. The volume of timber consumed in trestle construction across the major logging regions was enormous. A single large trestle might consume a million board feet of structural timber. The total trestle construction in the Pacific Northwest logging industry alone over the period from about 1880 to 1940 probably consumed several billion board feet of timber. Much of this timber was the highest grade of structural lumber taken from the largest and oldest trees of the surrounding forest. The trestles thus consumed in their construction the same kind of old growth timber that the logging operations they served were producing for the broader lumber market.

[00:27:48]The trestles were in this sense an additional drain on the original forest resource of the regions where they were built. The technology of wooden bridge construction did not entirely die out with the decline of the logging trestle.

[00:28:03]Some of the techniques continued to be used in smaller applications including agricultural bridges, mining bridges, and temporary military bridges. The US Army Corps of Engineers maintained training programs in heavy timber construction throughout the 20th century with the techniques originally developed for logging trestles forming part of the standard curriculum for combat engineers. The Bailey Bridge developed by the British during the Second World War used some construction principles that had been refined in heavy timber bridge work. Although the Bailey itself was a steel structure, the modern timber bridge industry which exists in a limited form for specialized applications continues to use some of the construction techniques developed by the loggers of 100 years ago. The men who built and worked the wooden trestles like so many of the men of the early industrial American lumber business are nearly all gone now. The last of them, the youngest workers from the construction projects of the 1930s, would have been born around 1910 to 1915 and would now be over a 100 years old.

[00:29:15]The senior workers from the same projects, the bridge foreman and the experienced framers have been dead for decades. The oral history collections at Humboldt State, the University of Oregon, the West Virginia State Archives, and several other institutions preserve recordings of crews from the later years of the wooden trestle era.

[00:29:36]But the men who actually built the great trestles of the 1880s and 1890s were already dead by the time anyone got around to interviewing them. The bridges themselves, the actual physical structures are mostly gone. The Larabe Creek trestles are gone. The big creek trestle is gone. The hetchy trestles are mostly gone with only a few rotted bents remaining in the upper Tumni Canyon. The cast trestles still stand, but they are mostly rebuilt rather than original with the rebuilds maintaining the original profile while replacing the actual structural timber every few decades. The total surviving original wooden trestle work of the kind that supported the great American logging railroads of the early 20th century is a tiny fraction of what once existed. What the wooden trestles represent in the larger industrial history of the country is a particular form of large-scale construction adapted to a specific set of economic and geographic constraints.

[00:30:44]The country had abundant timber and limited capital. It had steep mountain country to traverse and limited skilled engineering manpower. It had urgent demand for timber products and limited time to build the infrastructure necessary to harvest them. The wooden trestle was the solution that the industry developed working with the materials and the labor available to it and the result was a class of structures that achieved engineering performance that would have been considered impressive in any era. The bridges stood, the trains crossed them, the logs came out of the mountains, and then the era ended and the bridges were replaced with steel or simply abandoned. and the technology that had built them passed out of common practice and into history.

[00:31:33]The remaining traces of the wooden trestle era are scattered across the western and eastern American forest country. A surviving bent here, a foundation stone there, a section of grade visible on a hillside that no train has crossed in 70 years. The trestles are mostly gone, but the country they once crossed is still there. You can walk through it in some of the surviving national forests and parks and see where the trestles ran and imagine what they looked like and consider the men who built them with hand tools and animal power and an enormous quantity of cut timber working on structures that would have given pause to any professional bridge engineer of their time.