Necedah Railroad Bridge

Located in Necedah, this truss and girder bridge carries the former Chicago & North Western Railway mainline across the Yellow River and Canadian National Railway (former Chicago, Milwaukee, St. Paul & Pacific Railroad). The original alignment of the C&NW came into Necedah further north, crossing the Yellow River near the present-day dam. The original bridge consisted of a wooden Howe through truss and timber pile trestle structure. When the Milwaukee, Sparta & North Western Railway (MS&NW) constructed into Necedah in 1911, the line was realigned further south, and the present bridge constructed. The original line was retained for some years, but was eventually abandoned in 1935.

Currently, the bridge consists of a double track 150-foot, riveted quadrangular lattice through truss span, three single track 69-foot deck plate girder spans and a double track 75-foot through plate girder span over the Milwaukee Road line. The entire bridge is set onto concrete substructures, and a second track on the north side was never installed on the bridge. The truss and through girder span were both constructed for two tracks, as these spans would have been difficult to modify with two tracks. Deck plate girder spans could easily be modified for a second track by simply adding a second parallel structure. Pennsylvania Steel Company constructed the truss and deck girder spans, while the King Bridge Company constructed the through girder span. All substructures of the bridge were constructed by the Bates & Rogers Construction Company. All three of these contractors had significant contracts for the bridges along the MS&NW line.

The truss span uses a standard design for the era, with heavily constructed members and a standard floor. The endposts, top chord and bottom chord all use built-up members, with heavy V-lacing. Many of the diagonal members are composed of rolled beams and steel bars, while some tension members are composed of a V-laced built-up beam. Typical of lattice truss spans constructed for the MS&NW, the connections are heavily built, using large plates. The floor is composed of heavy floorbeams and two stringers per track, typical of truss spans from this era. The upper lateral bracing is composed of V-laced built-up beams, while the lower lateral bracing is composed of solid bars. Also typical of lattice truss spans constructed for the MS&NW, the portal bracing uses an M-frame design, constructed of V-laced built-up beams. The deck plate girder spans use a standard design, with heavy girders and an open deck. The through girder span also uses a typical design, with massive girders, a traditionally composed floor and curved and tapered girder ends.

This type of truss design is relatively uncommon throughout the United States. However, a few railroads preferred the design, such as the Chicago, Rock Island & Pacific Railway (Rock Island), the Chicago & North Western Railway (C&NW) and the Omaha Road. Spans constructed in the late 1870s and early 1880s for the C&NW featured an arched and pedimented lattice portal bracing, light sway bracing and laced members. The second generation was nearly exclusively constructed by Lassig Bridge & Iron Works between 1884 and 1900, and featured heavier members and a pedimented portal bracing. While the design fell out of favor for the Rock Island and Omaha Road around the turn of the 20th Century, the design remained popular with the C&NW into the 1920s. 19th Century versions of this design were primarily constructed out of iron, while 20th Century versions of this design used much heavier members and were constructed of steel. The C&NW preferred this design, as it was both strong and demonstrated great resilience in case of a derailment. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being moderately significant, due to the truss design and large size.