Northwestern Railroad Bridge

Located in Eau Claire, this iconic lattice deck truss bridge (simply known as the "High Bridge") once carried the Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road) mainline over the Chippewa River. When the West Wisconsin Railroad reached Eau Claire in 1870, the Chippewa River presented a formidable challenge. At Eau Claire, the river runs through a deep gorge, with large bluffs on either bank. In addition, the railroad had constructed a large fill through the city, which required a tall bridge across the river. The first bridge at this location was a large wooden Howe deck truss span, set onto timber substructures and approached by timber pile trestle spans. This bridge was completed in mid-1870, and allowed the railroad to continue constructing the new mainline. Large timber deck trusses were used for the first bridges at a number of locations along this line, as iron had not yet become the economical option to developing railroads. Within 10 years, the wooden bridge had become too light for traffic, and plans were made to replace it with a more substantial iron and stone structure.

Work on a new bridge began in July 1880, when cofferdams were constructed to reach the bedrock beneath the river. The first stone for the new bridge was laid on the evening of August 4th, 1880, and work rapidly progressed through the rest of the year. Work on erecting the superstructure began on January 10th, 1881, and the bridge was completed on March 25th, 1881. Upon completion of the bridge, the wooden bridge was removed. Construction of the substructures was carried out by James McClure and an unknown individual named Mr. Hanscom. Iron for the trusses was fabricated by the Leighton Bridge & Iron Works, and the superstructure was erected by O.F. Hilt of that firm. O.F. Hilt had worked on erecting several lattice trusses for the Omaha Road between 1880 and 1881. The new bridge consisted of four large iron deck truss spans, approached by a smaller deck truss span on either end. Over 450 tons of wrought iron was used in the construction of the bridge, with a total cost of $100,000. O.F. Hilt took great pride in this structure, and that there were no injuries during the construction. The bridge quickly became an icon for Eau Claire, and became a symbol of progress and industry in the city. Local newspapers considered the bridge a magnificent piece of work, and one of the finest iron bridges ever constructed.

By the late 1890s, the bridge had become too light for traffic, and would be altered to meet new loading requirements. In 1898, the approach spans were replaced by new deck plate girder spans, and the stringers of the main trusses were replaced by heavier stringers. It is likely that the original approach trusses were reused at another location after replacement, as was typical practice for the Omaha Road. Lassig Bridge & Iron Works fabricated the new approach spans and completed the repairs. The 1898 upgrades gave the superstructure of the bridge its present configuration.

During the early 20th Century, the Omaha Road began double tracking the line between Wyeville and St. Paul. Instead of replacing this bridge, a new cutoff was constructed further north, including a new bridge across the Chippewa River. The original mainline was retained to serve various industries. The west end of the original mainline was abandoned in the mid-20th Century. Throughout the 20th Century, it does not appear that this bridge received any significant upgrades or alterations. During the late 20th Century, light diesel engines were used to cross the bridge, as heavier locomotives were restricted from the structure. The remainder of the line was abandoned in 1992, and the bridge was spared demolition due to the Xcel Energy pipeline attached to the bridge. Ownership of the bridge was transferred to the City of Eau Claire for $1 in 2007. In 2014, Eau Claire began constructing a new wooden deck, railing and lighting. The bridge was officially opened to pedestrian traffic in 2015.

In June 2021, a strong storm blew a tree down on the deck, causing minor damage to the railing and deck. During an inspection of the bridge, it was noted that a tree growing in the top of the center pier (pier #3) caused the top of the pier to crumble and fail, shifting the large deck truss spans. Due to the imminent danger of collapse, solutions were urgently sought to either repair or safely remove the bridge. Significant community activism and enthusiasm surrounded the possibility of repairing the bridge, which led to the Eau Claire City Council unanimously accepting a proposal for emergency repairs in July 2021. A contract was awarded to Ayres Associates for the design of the repairs, and Kraemer North America for the construction of the repairs.

Throughout the fall of 2021 and early 2022, repairs were made to the bridge, including the removal of the top of the center pier and replacement with a decorative faux stone concrete. Additional repairs included deck repairs and mortaring the joints in the masonry. Repairs to piers #2 and #4 included the removal of the top courses of stone and a similar repair. Repairs were completed by constructing a large causeway into the river, using a system of jacks and falsework to hold the ends of each spans while the piers were reconstructed, and placing the spans onto the reconstructed piers. The concrete repairs were carefully constructed and colored to match the texture and color of the stone they replaced. The bridge officially reopened on March 28, 2022, with repairs having cost $3.9 Million. The award project received significant notoriety, with a local photographer documenting the progress. In 2023, the project was awarded the 2023 Historic Preservation Award through the Wisconsin Historical Society and the 2023 Public Works Project of the Year award in the Small Cities/Rural Communities Historical Restoration/Preservation category through the Wisconsin Chapter of the American Public Works Association (APWA). The repairs will help ensure that the historic bridge remains standing and in good repair for years to come.

The bridge consists of four 180-foot, 17-panel, riveted quintuple intersection Warren (lattice) deck truss spans, approached by an 80-foot deck plate girder span on either end. The superstructure rests on five stone piers and two stone abutments. The entire bridge is 890 feet long, and the deck of the bridge is located 82 feet above the river. When the bridge was converted to trail use, the original ties were removed from the bridge, and replaced with new ties. A wooden deck was installed on these ties, and the railings use a combination of wood and decorative iron. Numerous decorative luminaries have been installed on the south side of the bridge, and a lookout platform has been installed above each of the five piers.

The main truss spans use an exceptionally rare quintuple intersection lattice deck truss design, and may have been the only like it ever constructed. Most lattice trusses from this era were quadruple intersection spans, which were not as deep or complex. A quintuple intersection span results in each member crossing four others, creating five bays on each side. The trusses use a trapezoidal shape, which are 30 feet high, 18 feet wide at the base and 10 feet wide at the top. The endposts of the truss use a built-up design, consisting of two channels connected by a V-lacing. The bottom chords consist of two parallel channels, which are connected at the lower connection points. The top chord consists of an upside down U-shaped channel, which is connected by a combination of Z-lattice and V-lattice running the length of the chord. Compression members of the truss web consist of parallel beams, which are connected by an X-shaped lattice. Tension members are composed of two parallel beams. The ends of the truss use two laced members, which run longitudinally between the endpost and the first intersection. Typical of early riveted spans, the bridge uses both gusset plates and holes drilled through the members. Each member is riveted at each intersection. The floor is composed of four stringers, arranged into two sets of two. In addition, a wooden stringer runs along the top of each top chord. The floorbeams are constructed of two parallel I-beams, placed at each panel point. Interior bracing inside the truss uses a triangular shape, connecting each lower connection to the mid-point of each floorbeam. Both the interior bracing the lower lateral bracing use simple iron beams. The top lateral bracing appears to be integral to the floor system, and is heavily constructed using solid members.

The deck plate girder spans uses a standard design, with heavily constructed girders, typical X and lateral bracing, and an open deck. These spans are set onto large stone pedestals at the abutment. The pedestals were constructed to account for the height difference of the previous approach spans and the current approach spans. At the ends of the trusses, the girders are balanced on large frames, which appear to have reused portions from the original approaches. The frames use two angled built-up columns, which follow the contour of the trusses. The columns use an X-shaped lattice, and are tapered upwards (i.e., wider at the bottom). These columns are connected by a solid member at the bottom. A large plate girder has been installed on top of the columns, which appears to have been added when the approaches were reconstructed. The columns are connected to the endposts of the truss by a series of iron plates.

The three river piers are founded on stone which is laid to bedrock, while the outer piers and abutments are founded directly on bedrock. Stone for the base of the river piers was quarried at Mankato, Minnesota; while stone for the tops of the river piers, the outer piers and the abutments was quarried at Menomonie, Wisconsin. The river piers used a typical design, with large ice breakers on the upstream side of each pier. The outer piers use a typical square design, and it is unknown how far below ground level the piers extend. Limestone bluffs along the banks of each river may indicate that these piers are relatively shallow. The abutments use an elongated design, which was used at numerous other bridges on the Omaha Road. Repairs to the piers include a concrete base, which was likely added in the early 20th Century to protect the piers from scour. It is believed that these repairs were constructed by an unknown contractor. The tops of the outer river piers (piers #2 and #4) have had the first few courses of stone removed, which has been replaced by a colored concrete faux-stone. The top half of the center pier has been reconstructed with the same colored concrete faux-stone.

The Leighton Bridge & Iron Works was originally founded by Thomas Leighton in 1870 in Rochester, New York. A prominent Civil Engineer of the era, Leighton was born in 1818 in Augusta, Maine. It is believed he spent his early career building railroad bridges in Panama, before he moved to Rochester with his wife Kate in 1854. Leighton partnered with John Fowler, and the pair opened an iron works in the 1850s. After John Fowler died in 1868, Thomas Leighton opened his own bridge works in 1870, and was primarily focused on building iron railroad bridges. The shops were located at Leighton Avenue and Culver Road in Rochester. By the early 1870s, his shop was fabricating numerous railroad bridges each year, and was one of the main contractors working with the New York Central Railroad. In 1874 alone, over 120 examples of various lattice truss designs were produced for the New York Central. During the 1870s, Leighton mentored other prominent bridge builders, including Charles Hilton and John Alden.

Charles Hilton had previously worked with the New York Central, and had been involved in successfully designing a lattice truss for railroad use. Hilton worked under Howard Carroll, the Chief Engineer of the New York Central. Carroll had studied lattice trusses in Europe during the 1850s, and the pair constructed the first American version of the design in 1859. Hilton would perfect the design by the mid-1870s, creating a structure where all members intersect at perfect right angles. This design became known as the "Leighton Lattice Truss", and would be mass produced by the company. Through the late 1870s, the company grew further, and began shipping bridges to the Midwest. In particular, the Omaha Road, the Chicago & North Western Railway (C&NW) and the Chicago, Rock Island & Pacific Railway (Rock Island) used the design heavily in the late 1870s and early 1880s. The Leighton Bridge & Iron Works was also an innovator in field riveting truss spans. Typically, bridge components would have to be riveted at shops and assembled on-site. This made the use of riveted connections between members impractical, as entire truss webs would need to be shipped assembled. With the lattice design, hot rivets were required to be installed in the field, adding to the complexity of these spans. Thomas Leighton retired in 1881 due to declining health, and the shop was sold to John Alden, who partnered with Moritz Lassig in 1881 and began to lease the Rochester plant. Thomas Leighton died in Rochester in 1886.

After John Alden and Moritz Lassig partnered to form the Alden and Lassig Bridge & Iron Works 1881, production of the iron lattice trusses continued at a steady rate. The two continued to innovate and develop stronger variations through the 1880s. In 1884, the pair purchased the Rochester plant. In 1886, the partnership dissolved when Mortiz Lassig moved back to Chicago to form the Lassig Bridge & Iron Works. John Alden retained ownership of the Rochester plant, opening the Rochester Bridge & Iron Works in 1886. The Lassig Bridge & Iron Works continued to produce lattice trusses, as well as began the production of other bridge designs, including plate girders. This company became the preferred bridge fabricator of many Midwest railroads, including the Omaha Road and the C&NW. Between 1886 and 1900, nearly all iron and steel bridges constructed for the two railroads were fabricated by the Lassig Bridge & Iron Works. In 1900, both the Lassig Bridge & Iron Works and the Rochester Bridge & Iron Works were merged into the newly formed American Bridge Company. Moritz Lassig died in Germany in January 1902. American Bridge Company closed the Rochester plant in 1903, and the plant was demolished by the 1950s. The Lassig plant remained open until 1928, when the plant was sold to another industry. The shops were demolished in the 1980s for commercial redevelopment.

James McClure was a prominent railroad contractor and quarry owner in the Upper Midwest during the late 19th and early 20th Centuries. McClure moved to St. Paul, Minnesota in the 1870s, where he began building bridges, including the first bridge across the Mississippi River at Anoka, Minnesota. McClure also owned a quarry northeast of Mankato, where significant amounts of quality limestone were quarried. McClure gained prominence during the 1880s as he began contracting with the Omaha Road for the construction of stone bridges. McClure became heavily involved with the Omaha Road, constructing a large number of bridge substructures, arches and culverts using stone quarried at the Mankato quarry. He also was heavily involved with the double tracking of the line between Wyeville and St. Paul. McClure retired in 1912, and passed the construction business to his son, John. James McClure died at St. Paul in 1916, aged 74.

While lattice truss spans were relatively uncommon through the United States, the Chicago & North Western Railway (C&NW) and Omaha Road used the design extensively. Other railroads in the Midwest also occasionally used the design, although not as frequently. Engineers for the C&NW and Omaha Road favored the design, due to its resilience and greater strength without sacrificing economy. Metal lattice truss designs were initially developed for railroad use in the 1870s, often using deep spans with numerous intersections. Through the mid-1880s, innovations allowed the spans to be into double intersection spans. While the Omaha Road stopped using lattice trusses in the early 20th Century, the C&NW continued to use lattice truss designs nearly exclusively into the 1920s. This shift represents one of the few known instances where C&NW and Omaha Road engineers had differing opinions on bridge design.

While lattice truss designs were popular for some railroads, the use of a quintuple intersection span is virtually unheard of. This design was likely chosen due to the lengths and depths required for the spans. During this era, it was uncommon for wrought iron lattice truss spans to exceed 150 feet in length. Typically, long spans had been constructed using a Whipple design or other variations of the Pratt design. It is doubtful that other examples of this design were constructed in the United States, and there is no other known examples of this design surviving in the world. An additional unusual feature of the bridge is the shape of the trusses, which are wider at the bottom than the top. This design was likely chosen to account for the depth of the trusses.

Alterations to the superstructure of the bridge are overall minor, and are old enough that the alterations themselves are considered historic. The alterations to the substructure do not significantly change the characteristics of this historic bridge, and instead have provided the structure with a more stable future. Overall, the bridge appears to be in fair to good condition, and the recent repairs should help ensure this bridge remains standing for years to come. The author commends the City of Eau Claire and all involved with the 2021 repairs. These repairs show that historic bridges can feasibly be repaired with no significant loss of historical significance. It is hoped that the repairs seen on this bridge will inspire other communities to repair historic bridges instead of replacing them. The author has ranked this bridge as being nationally significant, due to the exceptionally rare design, age, builders and reuse. This bridge is likely the most significant railroad bridge in Wisconsin, based on its age, design and builders. In addition, the bridge is among the most significant railroad bridges in the entire United States. This bridge is exceptionally unique, as it is the only known quintuple intersection lattice deck truss remaining in the world. The bridge is also one of the few surviving products of the Leighton Bridge & Iron Works, a company that can be credited with significant advancements in early iron railroad bridge construction. The bridge was listed on the Wisconsin State Register of Historic Places in May 2024, and efforts are ongoing to have the bridge listed on the National Register of Historic Places.