Thacher Truss Bridge in background. Photo courtesy of Luke Harden.
A few months ago, the Chronicles did a special on the Thacher truss bridges, designed and patented by Edwin Thacher and first used in 1884 in the state of Iowa. To refresh the reader’s memory, the Thacher truss is a combination of Warren, Kellogg and Pratt truss with an A-frame in the center panel of each truss span. While the Wrought Iron Bridge was reported to have built these trusses, using the exact design prescribed by Thacher, the King Bridge Company built the hybrid version of the design that resembled a Warren truss bridge with a center panel that is half the length of the outer panels. If you count in the Phillips Mill Crossing in Rockford, the pony truss variant located west of Milford and the three hybrid Thachers in Emmet County, Hamlin County (South Dakota) and near Hastings, Minnesota, a total of ten Thachers were reported to have been built.
With this mystery bridge, as seen in the picture, let’s make it eleven Thachers.
Fellow pontist Luke Harden came across this picture of a Cedar River crossing in Waverly. According to the information, the bridge (which is in the background behind the wagon bridge) served the Chicago and Great Western Railroad and featured at least three spans of the Thacher truss. The bridge was about 400-500 feet long, looking at the picture more closely, with each truss span being about 120 feet long. The bridge served traffic until a train derailment brought down the entire structure in 1914.
Collapse of the bridge in 1914. Photo courtesy of Hank Zaletel
This means that the structure was in place for no longer than 30 years. Even more curious is the fact that the trusses were built using a combination of wood and steel, making the railroad bridge look rather unusual for the materials used for bridge construction. While bridge builders used iron and wood for construction in the 1860s and 1870s, it is even rarer to see a wooden truss bridge built using steel truss support, although one is reported to exist in Allamakee County in the Red Bridge (abandoned for over four decades).
While the bridge no longer exists- a replacement was built but only existed for another 30 years before the railroad abandoned the line and removed the bridge- piers from the structure can be seen from Adams Parkway Bridge, located next to it in the northeast end of the city. Yet more information about the bridge is needed. For instance: when exactly was the bridge built? What were the exact dimensions? Who built this bridge? And lastly what was the cause of the mishap. Any information on the bridge can be submitted using various channels including the comment section of the Chronicles.
Furthermore, information is needed for the Adams Parkway Bridge, for the two-span truss bridge existed before its replacement in 1968, yet its markings is similar to a bridge built by the Clinton Bridge Company at the turn of the century, including the portal bracings. Both bridges will be included in the Iowa Truss Bridge book, which is being compiled by the author even as this article is being posted. Any information would be much appreciated.
With this latest discovery, it leads to the question of how many other Thacher truss bridges were built in Iowa, let alone in other parts of the US. We’ll find out more as other pontists and people finding old photos will bring bridges like this one to the attention of the readers and other interested people alike.
