NS Des Moines River Bridge

Located south of Runnells, this large through truss and steel stringer bridge carries a former Wabash Railroad branch line over the Des Moines River alongside Iowa Highway 316. Originally, the Wabash and Chicago, Burlington & Quincy Railroad (CB&Q) operated branch lines between Albia and Des Moines on opposite sides of the Des Moines River. The Wabash operated a line which crossed the Des Moines River near Harvey, Iowa and continued along the north side of the river into Des Moines, while the CB&Q operated a line along the south side of the river, which crossed the Des Moines River in southeast Des Moines. using a four-span through truss bridge, fabricated in 1879. Starting in the 1950s, the Army Corps of Engineers planned a series of improvements to reduce flooding along the Des Moines River. One of the selected projects was the Red Rock Dam, which would be constructed near Pella and result in a large pool forming upstream. As a result, the Wabash line would be inundated. The Army Corps of Engineers worked with the Wabash and CB&Q to devise a solution. It was decided that the CB&Q and Wabash would share a line between Albia and Des Moines. The CB&Q line between Albia and the small town of Swan would be retained, a new bridge constructed across the Des Moines River, and the Wabash line between Runnells and Des Moines retained. The CB&Q between Swan and Des Moines and the Wabash between Albia and Runnells would be abandoned. Work on the project began in 1963, and was completed in late 1964. Currently, the bridge consists of three 188-foot, 6-panel, riveted Warren through truss spans, approached by eighteen 43-foot steel stringer spans on either end. The entire bridge is set onto concrete substructures.

The truss spans follow a typical mid-20th Century design, with punch-plate style members, a standard floor and a utilitarian appearance. The "punch-plate" design was introduced in the mid-20th Century as an alternative to X-lacing and V-lacing. A punch plate consists of a simple plate with large holes punched into it. Both the top chord and endposts use a built-up design, consisting of a box-shaped beam connected by punch-plate pieces on the interior and a solid plate on the exterior. The bottom chord, the diagonal members and alternating vertical members use a similar design, with punch-plate pieces on both sides of the beam. The first, center and fifth vertical members all consist of heavy solid beams. The floor system consists of plate girder floorbeams and two heavy plate girder stringers. Both the lower and upper lateral bracing consist of standard steel bars of different shapes. The portal bracing is heavily constructed, using an A-frame design with a punch-plate top strut and solid beams for the remaining portions. The sway bracing also uses an A-frame design, and consists of solid beams for the top strut and L-shaped bars for the remaining portions. The approach spans each consist of four shallow beams, arranged equidistant. All piers use a standard rounded rectangular shape, and the abutments use a standard design with short sloped wing walls.

An unknown contractor fabricated the superstructure, while L.G. Barcus Company constructed the substructure. The bridge was designed by Sverdrup, Parcell & Associates; a notable 20th Century structural designer. In particular, this firm is noted for having designed the Chesapeake Bay Bridge-Tunnel; the ill-fated Interstate 35W Mississippi River Bridge in Minneapolis, Minnesota and a handful of notable sports stadiums. The Warren pattern became popular for railroad trusses in the early 20th Century, especially as riveted connections became more economical. This pattern offered a simple, economical and durable design. After World War II, the design remained popular, but instead used high-strength steel and punch-plate style members. Into the 20th Century, the design has continued to be the most popular truss pattern for both railroad and roadway use. Since the initial construction, the bridge has seen no significant alterations. Today, Norfolk Southern Railway (NS) and BNSF Railway share rights to the bridge. Overall, the bridge appears to be in good condition, with no major defects noted. The author has ranked this bridge as being locally significant, due to the truss design and newer age. The bridge remains among the longest railroad bridges in Iowa and serves an important role in the regions railroad network.