Quinsippi Island Railroad Bridge

Since the early 1850s, Quincy had been an important railroad town, located along the Mississippi River. The Chicago, Burlington & Quincy Railroad (CB&Q) operated a line into Quincy; and across the Mississippi River, the Hannibal & St. Joseph Railroad operated a line to Kansas City, Missouri. During the 1860s, the two railroads desired to construct a bridge across the Mississippi River, connecting the two systems. In 1866, the crossing was approved by the United States Congress, and the Quincy Bridge Company was incorporated to oversee the work. The crossing would be comprised of two main structures, including a large bridge across the main channel, and a smaller structure across Quincy Bay. The bridges were designed by Thomas C. Clarke, and fabricated by the Detroit Bridge & Iron Works. The railroad company provided the labor for construction of the substructures. Both structures would utilize swing spans to accommodate riverboat traffic, and were completed in 1868. The two bridges were initially connected by a wooden trestle, which was filled during the early years of the structure.

The first bridge across Quincy Bay consisted of a 190-foot Bollman deck truss bridge, approached by two 84-foot Bollman deck truss spans on either end. The trusses were set onto stone piers and abutments, constructed of dolomite stone quarried at Keokuk, Iowa and Grafton, Illinois. The abutments were constructed with a 30-foot stone arch, a design occasionally used to stabilize slopes at the ends of bridges. The truss spans were fabricated by Detroit Bridge & Iron Works, using a license granted by Wendel Bollman. Bollman trusses were a patented design, used during the 1860s as railroads began to develop truss bridges. Typical of this design, the first Quincy Bay Bridge utilized pinned connections and was constructed of wrought iron. This bridge served until the 1880s, when the bridge became obsolete for railroad traffic.

Throughout the 1880s, the CB&Q designed and fabricated many of their own iron and steel bridges at shops placed strategically throughout the system. While most railroads operated shops that could repair cars and engines, relatively few railroads maintained shops that could fabricate heavy steel structures. Often, the cost of maintaining the skilled labor necessary for fabricating structures was not cost effective for railroads. Instead, railroads most often purchased bridges from steel manufacturing companies. Bridges were often difficult to manufacture, and were larger and heavier than most cars and smaller structures. The CB&Q maintained shops capable of fabricating bridges at Aurora, Illinois and West Burlington, Iowa, although other shops were believed to have manufactured bridges.

In 1886, the Aurora Shops of the CB&Q fabricated new iron girder spans to replace the original Bollman truss bridge. The new spans would consist of four 84-foot deck plate girder spans, and a 190-foot deck plate girder swing span, which would reuse the stone substructures and approaches from the original bridge. Work on fabricating the new bridge was reportedly completed in April 1886, and the new bridge installed that year. Railroad records indicate that the five spans weighed over 320 tons when fabricated. The 190-foot deck plate girder span was likely among the largest structures manufactured by the CB&Q shops.

Since the 1886 reconstruction, the bridge has changed relatively little. A new bridge south of this structure was constructed in 1899. The same year, most of the main channel bridge was replaced. In 1960, the CB&Q constructed a new bridge and cutoff north of this bridge, which included a new bridge across the Mississippi River. The bridge was abandoned shortly after, although it was used as a tourist railroad into the 1980s. It has since been converted to road use, carrying Quinsippi Island Road. Overall, the bridge appears to be in fair condition, with no significant deterioration noted. If funding is available, this bridge should receive a historically sensitive rehabilitation, lengthening the life of the structure. The author has ranked the bridge as being highly significant, due to the age and fabrication of large plate girders by a railroad shop.