IC Little Sioux River Bridge #3

Located north of Correctionville, this attractive through truss bridge is the third crossing of the Little Sioux River along the former Illinois Central Railroad Onawa Branch. When the railroad was first constructed at this location, the bridge consisted of a single through truss span, set onto timber pile piers and approached by timber pile trestle spans on either end. Many railroads commonly used this technique when first constructing new lines, as it allowed for approach embankments to settle without damaging expensive components of bridges. In approximately 1895, the bridge was rebuilt with two new stone piers. The most recent upgrades to the bridge came in 1918, when the north and south approach trestles were rebuilt. Currently, the bridge consists of a 150-foot, 8-panel, pin-connected wrought iron Pratt through truss span, set onto stone piers. Both the north and south approach initially consisted of ballast deck timber pile trestle spans, set onto timber pile bents. Union Bridge Company fabricated the truss span at their Buffalo, New York plant; while an unknown contractor constructed the stone piers. Timber components of the bridge were constructed by railroad company forces.

In the mid to late 1880s, the IC ordered a large quantity of truss spans from the Union Bridge Company for use on new branch lines and to replace existing light iron trusses. This bridge utilizes built-up vertical members, a traditionally constructed floor and a decorative portal bracing. The top chord and endposts are composed of built-up beams, with a solid plate on the exterior and X-lacing on the interior. The bottom chord is composed of eyebars, with two sets of two at the center panels and two sets of one at the outer panels. Vertical members consist of built-up beams, composed of tight X-lacing. The diagonal members consist of eyebars and use a rectangular shape. Similar to other truss spans from this era, the outermost lower connections use a double connection design, with a pinned connection located above and below the floorbeam. The floor is composed of two plate girder stringers, which are affixed to plate girder floorbeams. Additional bracing is present between the two stringers. The lower lateral bracing is composed of metal rods, which are looped at the end and pinned into the floorbeams. The upper lateral bracing consists of metal rods, and is affixed to the top chord. The portal bracing consists of a crested lattice beam with rounded lattice heel bracing. The sway bracing is composed of solid beams, which is connected to the vertical members by a rounded lattice heel bracing. The pier uses a standard rectangular shape, while the north abutment uses an elongated U-shaped design.

The Pratt truss design was the most popular railroad truss bridge design in the late 19th Century, as it was economical, durable and simple. However, the main limitation of this design was the length. In the mid-1880s, railroad spans of this design were generally limited to 200 feet or less, with most spans 150 feet or less. This bridge represents a typical sized span, and several similar examples were constructed for the IC. Since the original construction, it appears that no major alterations have been made to the bridge. After abandonment, the bridge was left intact and the land apparently was acquired by Woodbury County. The north approach trestle was demolished in the mid-1990s, while the south approach trestle remained largely unchanged until approximately 2019, when several spans collapsed. Overall, the remaining truss span and stone piers appear to be in fair to good condition, with no significant deterioration noted. The remaining south approach is in extremely poor condition, with further sections likely on the verge of collapse. Because the truss and stone piers remain in good condition, the remaining bridge would be a good candidate for reuse and preservation, although the location makes this highly unlikely. One far-fetched possibility for reuse would be to move and reuse the truss span at the Union Bridge Trail Bridge in Correctionville, another Woodbury County owned bridge, to replace an identical span that was demolished. The author has ranked this bridge as being regionally significant, due to the age and truss design.