CPKC Iowa River Bridge (Columbus Junction)

View an article discussing the 1910 reconstruction of this bridge (digitized by Google)

Located on the east side of Columbus Junction, this lengthy deck plate girder bridge carries a former Chicago, Rock Island & Pacific Railroad (Rock Island) mainline over the Iowa River at it's confluence with the Cedar River. Similar to many large bridges constructed by the Rock Island, this bridge has a lengthy history of partial replacements and modifications. The first bridge at this location was likely a wooden Howe through truss bridge, consisting of six 150-foot spans set onto stone piers and approached by lengthy timber pile trestle approaches on either end. In 1869, the bridge was rebuilt with six new combination Thatcher through truss spans, reusing the same piers. Combination truss spans consisted of both wood and iron members, with the placement of each intended to maximize strength. In 1891, the main spans were replaced by six 150-foot, riveted quadrangular lattice through truss spans, set onto the same stone piers. It is believed these spans were fabricated by Lassig Bridge & Iron Works, which did significant work for the Rock Island during this era. Between 1902 and 1904, several new stone piers were constructed at the west end of the bridge, and nine new deck plate girder spans were installed. Further alterations were made to the bridge in 1905, when several of the original stone piers were replaced with concrete.

In 1910, the Rock Island undertook a major project to replace the truss spans with eleven new deck plate girder spans (spans #2 through #12), and several new concrete piers were installed. In addition, it is believed the stone piers of the west approach were altered at this time to raise the grade of the bridge. Due to the cost of falsework, it was decided to instead to install the new girders using an innovative method where a temporary hoist was installed on the trusses and the spans lowered into place. It is unclear if the truss spans were reused at other locations. In 1912, the east approach was filled and a single deck plate girder span (span #1) was installed. In approximately 1920, spans #16 and #17 were reconstructed with heavier plate girders. Further alterations were made to the bridge in 1945-46, when spans #3, #4, #7, #11 and #14 were replaced with newer spans of a similar design. The most recent alteration to the bridge came in approximately 1995, when spans #13 and #19 were replaced with modern deck plate girder spans. From east to west, the bridge consists of twenty one deck plate girder spans, including one 60-foot span (span #1), one 75-foot span (span #2), five 78-foot spans (spans #3 through #7), three 103-foot spans (spans #8 through #10), one 78-foot span and one 75-foot span (spans #11 and #12), seven 68-foot spans (spans #13 through #19), one 50-foot span (span #20) and one 45-foot span (span #21). The bridge is set onto a combination of concrete and stone substructures, which were constructed and altered at various times

Due to the variety of build dates, the superstructure uses a number of different designs. Spans #1, #2, #5, #6, #12, #15, #20 and #21 all use a standard design for the early 20th Century, with two heavy plate girders and an open deck. Spans #8, #9 and #10 are similarly constructed, but consist of significantly heavier plate girders. These spans were unusually large for the era, and it was decided to use larger spans instead of adding an additional pier due to the slight cost differences. Spans #16 and #17 appear to also use heavy plate girders, which may have been modified. A distant view shows that the corners of the girders were cut away to prevent alterations to the piers. It is unclear if these spans were constructed from secondhand material, and little is known about the history of the spans. Spans #3, #4, #7, #11, #14 and #18 all use a typical mid-20th Century design, with welded plate girders and an open deck. Spans #13 and #19 both consist of a modern steel design, with heavy bolted connections. The substructures follow a handful of different designs, with the 1905-era piers using large rectangular structures and the 1910-era piers using smaller rectangular structures. The west approach piers are rectangular in shape, and are mainly composed of stone with a concrete cap. The east abutment follows a standard Rock Island design, with sloped wing walls, while the west abutment consists of stone capped with concrete and uses stepped wing walls. Stone for the substructures consists of a brown limestone, quarried at an unknown location.

A number of different contractors were involved with constructing the bridge. It is believed that McClintic-Marshall Construction Company fabricated spans #2, #5, #6, #8, #9, #10 and #12; while American Bridge Company fabricated span #1. Spans #3, #4, #7, #11, #14 and #18 were all fabricated by the Vierling Steel Works, while spans #13, #15, #16, #17, #19, #20 and #21 were fabricated by multiple unknown contractors. Piers #3, #5, #7 and #10 were constructed by Thomas Phee & Company in 1905. Piers #1, #2, #4, #6, #8, #9, #11 and #12 were all constructed by the Bates & Rogers Construction Company in 1910. It is believed this same firm altered the piers of the west approach as well. Multiple unknown contractors constructed both abutments and piers #13 through #20. Deck plate girder spans were popular for railroad use, as they were durable and easy to construct. Since the Rock Island was often in poor financial condition, the railroad rarely replaced entire major bridges. Instead, the company saved costs by constructing and altering large bridges in a piecemeal fashion. Overall, the bridge appears to be in fair to good condition, and remains regularly used. The author has ranked this bridge as being moderately significant, due to the unusual number of different spans and contractors.