Astico County Park Bridge

View the Historic American Engineering Record documentation for the Ninabuck Road Bridge

View the Historic American Engineering Record documentation for the Scofield Road Overpass

Located in Astico, this unique bridge reused two historic truss bridges from other locations in Dodge County. In the 1990s, Dodge County was working to replace aging bridges throughout the county. As part of the work, the bridges were documented and evaluated for historic significance and possible reuse. In conjunction with the Wisconsin Department of Transportation, several historic bridges were offered for reuse, with the condition that they would be removed from their original locations. When the Ninabuck Road Bridge and Scofield Road Overpass were removed, a plan was developed to reuse the structures to carry a pedestrian path over the Crawfish River in Astico County Park. For many years, the structures were stored in a field near Wisconsin Highway 16 and County Road T as discussions occurred on what should happen to the spans. A final plan to refurbish and reuse the two spans was approved in early 2005, and construction began in 2006. Janke General Contractors was selected to construct the new substructures and install the spans. A ribbon cutting ceremony for the new bridge was held on October 21, 2006. As part of the project, the two historic truss spans were installed onto decorative concrete substructures, and both were rehabilitated and received a new coat of tan paint. As part of the rehabilitation, a new wooden deck and railings were added to the bridge. Since the installation at Astico County Park, the bridge has not been altered, and today is a popular attraction.

Although the main span of this bridge was constructed for roadway use and had no railroad connection, the author feels that it is important to elaborate on this historic span. In early 1907, the Dodge County Board of Supervisors awarded a $2,515 contract for the construction of a bridge carrying Ninabuck Road across the Crawfish River near the Town of Elba, a couple of miles from Astico County Park. The new bridge was fabricated by the Elkhart Bridge & Iron Company; a firm known for fabricating steel roadway bridges, and was completed later that year. Originally, the bridge consisted of a main truss span, approached by a short steel stringer span on either end. The bridge was set onto a combination of steel caisson and stone substructures. After nearly 90 years in use, the bridge was replaced in 1996; and the truss span retained for future reuse. The truss span consists of a 123-foot, 8-panel, pin-connected Pratt through truss span. Because the bridge was constructed for roadway use, many of the features of this span are lighter than railroad bridges from the same era. The top chord and endposts are constructed using V-laced members, covered by a steel plate on the outside. The bottom chord is constructed of eyebars, a typical construction technique for bridges from this era. The vertical members are composed of built-up beams with extensive V-lacing, while the diagonal members are composed of steel bars and rods. Typical of early 20th Century roadway truss spans, the portal bracing is constructed using a decorative design, with extensive lattice and lattice heel bracing. In addition, the sway bracing is constructed using a V-laced beam. Both the upper and lateral lateral bracing are composed of steel rods, with the bottom bracing inserted into slots built into the floorbeams. The floorbeams use light plate girders, while the stringers are constructed of several parallel I-beams. Upon replacement, the truss span was moved in one piece, and it does not appear any significant alterations were made to the span. Today, this span retains excellent historic integrity, with all features the same as when it was originally constructed.

When Chicago & North Western Railway (C&NW) subsidiary Milwaukee, Sparta & North Western Railway (MS&NW) constructed a new line through Dodge County between 1910 and 1911, a number of overpasses were required for roadway traffic. Instead of constructing a new concrete structure, the MS&NW/C&NW opted to reuse secondhand railroad spans which were retrofitted to serve wagon and later automobile traffic. One such structure was constructed to carry Scofield Road immediately west of Lebanon, Wisconsin. This bridge was constructed with a 64-foot pony truss span, set onto timber pile piers and approached by timber pile trestle spans. The truss span was originally fabricated in approximately 1878 by the Leighton Bridge & Iron Works, likely at an unknown location in Iowa. Between 1877 and 1878, this company constructed approximately 13 64-foot iron pony truss spans for the mainline between Cedar Rapids, Iowa and Boone, Iowa. Reportedly, this span was originally part of a two span structure. In approximately 1890, the bridge was replaced by a new bridge, likely as part of double tracking work that was carried out in areas between 1888 and 1890. The spans were then strengthened by the Lassig Bridge & Iron Works in 1891, and installed as part of a two span bridge at Bridge #94 across Lawrence Creek in Lawrence, Illinois. In 1910, the Lawrence Creek Bridge was double tracked, and the pony truss spans replaced and sent to the American Bridge Company shop at Chicago, Illinois to be retrofitted for vehicle use. As part of the retrofit, the original floor system was reconstructed with new floor beams and wooden stringers, and outriggers were added to strengthen the span. One of the two spans was sent to carry Scofield Road near Lebanon, while the other was installed near Wiscona, Wisconsin; possibly at Teutonia Avenue. The Scofield Road bridge remained in use for 85 years until 1996; when the overpass was closed and the truss span relocated. To facilitate relocating the span, the structure was divided into two halves by removing the stringers and cutting the floorbeams. Upon installation at the current location, the floorbeams had to be repaired by installing new plates, reconnecting the two halves of the structure. While the truss span was 26 feet wide at its original location, its width was reduced to 15 feet when it was installed at the present location.

This span consists of a 64-foot, 7-panel, riveted double intersection Warren pony truss span. This design of span was used extensively by the C&NW between the late 1870s and early 1890s, as it provided a strong, simple and cost effective span. These spans were typically built in lengths of 64 feet, 72 feet and 84 feet. Similar to other spans from the same era, it is believed that this span is constructed using wrought iron, a material which the C&NW preferred in the 19th Century. This design of span was also particularly adaptable to be retrofitted for roadway use, as the short size and simple design made modifications relatively simple. Between the two modifications, the original light members have been extensively rebuilt and strengthened. The endposts, top chord and bottom chord all use a channel design, constructed of two parallel L-shaped beams riveted together. The diagonal members consist of solid L-shaped beams pressed together. Originally, the floor likely consisted of two stringers, placed underneath the rails. When the span was reconstructed, the original floorbeams and stringers were replaced with new material; and the stringers were replaced again upon relocation here. The current floorbeams consist of unusual shaped beams, which are heavily riveted. The stringers likely consist of several parallel beams. A number of additional plates and rivets were added to the span during the 1911 reconstruction, likely to strengthen the structure.

Railroads often relocated steel and iron spans, as it provided a cost effective way to upgrade bridges without requiring large amounts of new material. Often, when a span was no longer suitable for mainline use, it could be relocated to serve a branch line or an overpass, with or without repairs. Spans that were reused for roadway crossings were often among the oldest metal spans available along the railroad, and could not feasibly be rebuilt for continued railroad service. The C&NW was one of many railroads that utilized the practice of reusing railroad spans for vehicle use. In the late 19th and early 20th Century, hundreds of overpasses were constructed throughout the United States by reusing metal railroad bridge spans. As automobiles became larger and heavier in the 20th Century, these spans became outdated often had severe geometric deficiencies. Since the mid-20th Century, a vast majority of reused railroad spans in the United States have been removed or replaced. Often, the metal portions of these bridges were still serviceable, but poor geometry, limited records and deteriorated timber components required the complete replacement of the structure. Because these bridges were typically maintained by the railroad, records are not typically publicly available. As a result, the complete history of the bridge is often unclear, and historic determinations are made using absent or incomplete information. The Scofield Road overpass was one of two spans near Lebanon demolished at the same time. Fortunately, the metal spans were still in fair condition, and both spans were deemed historic and offered for reuse. The nearby Poplar Grove Road overpass was reused in Washington County, where it now serves a landscaping contractor.

While truss spans were once a common sight along roads and railroads throughout the United States, the population has greatly dwindled since the mid-20th Century. Truss spans were typically constructed to cross larger creeks and rivers, as they allowed for a longer span length. The main drawback of truss spans was the "fracture critical" nature of many spans. This means that if any piece fails, the entire span was likely to fail. In addition, roadway spans in particular became too light for modern automobile traffic, leading to weight restrictions. Unlike simpler beam/girder bridges, truss spans were known for using innovative construction techniques, decorative features and other unusual features. Fortunately, as more and more truss spans are replaced, the importance of preserving these pieces of transportation heritage has resonated in communities throughout the United States. While many spans are no longer feasible for roadway or railroad use, these spans can often feasibly be reused for trails or golf course bridges. The Astico County Park Bridge is an excellent example of the reuse and preservation of historic truss spans that otherwise would have been scrapped. In addition, the two designs included in this structure are among the last remaining examples in Wisconsin. Much of the population of pin-connected trusses in Wisconsin has been replaced, while double intersection Warren spans have also dwindled since the early 20th Century. The author has ranked this bridge as being regionally significant, due to the innovative reuse, excellent rehabilitation and history of the two spans.