Pierre Railroad Bridge

View the National Register of Historic Places nomination for this bridge

Located north of US Highway 14 between Pierre and Fort Pierre, this large through truss bridge carries the Rapid City, Pierre & Eastern Railroad (former Chicago & North Western Railway) across the Missouri River. While the C&NW reached Pierre in 1880, desires to extend westwards towards Rapid City were delayed due to much of the land being occupied by Native American reservations. In 1905, large swaths of land west of the Missouri River were opened to settlement, and the C&NW began developing a route between Pierre and Rapid City. The C&NW incorporated a subsidiary, the Pierre & Fort Pierre Bridge Railway, to oversee development of the bridge across the Missouri River. At the end of 1905, a temporary wooden trestle was constructed across the Missouri River to facilitate construction, which would begin in 1906.

Construction on the permanent bridge began in the summer of 1906. The Arthur McMullen Company began construction on the seven stone piers. As part of the construction, large pressurized caissons were sunk deep into the riverbed. The stone for the piers was quarried at Ortonville, Minnesota. Work on the piers continued until the end of 1906. In 1907, the truss spans would be fabricated and erected. The truss spans were fabricated by the Pennsylvania Steel Company, which fabricated the individual components at the Steelton, Pennsylvania shops and shipped them to the bridge site. The Bernhisel Construction Company oversaw the erection of the bridge. Edward C. Carter and William H. Finley, the Chief Engineer and Assistant Engineer for the C&NW were in charge of designing the bridge. Work on the bridge was completed in the fall of 1907.

The bridge quickly became a vital transportation link for the State of South Dakota. The bridge was the only crossing of the Missouri River at Pierre, until a parallel highway bridge was constructed in 1926. While the bridge was designed with a swing span, it is believed to have only been opened once, at the time of initial construction. The swing span was constructed due to Federal Navigation requirements. The Missouri River was considered a navigable waterway, but commercial riverboat traffic had nearly completely ceased in this area by the time of construction

As initially constructed, the bridge consisted of three 350-foot pin connected 12-panel Pennsylvania through trusses, a 445-foot 6-inch swing span, which was built using a pair of modified 7-panel pin-connected Pennsylvania through trusses, joined over a center swing pier by a tower, and an additional 350-foot Pennsylvania through truss span on the east end. The bridge was originally approached by long trestle approaches on either end, and was set onto stone piers. The stone piers themselves consist of steel caissons, faced with stone and filled with a concrete core. Pennsylvania through trusses were commonly used for long spans, as the heavier members and sub-panels allowed for long spans, and provided greater loading capacity. As is typical with Pennsylvania spans, the top chord of the truss is a polygonal design.

The original trestle approaches quickly became unnecessary, and were gradually upgraded and filled. The east approach was nearly completely filled in 1920. Both approaches were reconstructed with the current deck plate girder spans in 1928. The east approach consists of a 65-foot and a 45-foot deck plate girder span, fabricated by the American Bridge Company. Concrete substructures were constructed for these spans. The west approach consists of a single 54-foot deck plate girder span, set onto a timber pier and approached by timber trestle spans. The girder span utilizes four girder lines, known as a "twinned" girder. Twinning was a technique often used by railroads, particularly when reusing salvaged girder spans. A plaque on this span indicates that it was fabricated in 1897 by the Lassig Bridge & Iron Works. It is currently unknown where the span came from.

This bridge is considered a landmark in South Dakota, and it is the only remaining swing span in the state. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The trusses on the bridge are exceptionally large examples of railroad trusses in South Dakota, and have very few alterations. While much of the gear system on the swing pier is still intact, the roller bearings at the end piers have been replaced with fixed bearings, effectively rendering the bridge unmovable. The author has ranked this bridge as being nationally significant, due to the unique large scale truss design, notable features and the bridges role in railroad development in South Dakota.