Mystery Bridge Nr. 26: Unusual Truss Bridge in Iowa

Portal and overhead view. Photos taken by John Marvig

Have you come across an unusual bridge while travelling or bridgehunting? If so, what did the bridge look like, and did you do some research to determine what bridge type it was? Many engineers came up with rather unusual bridge designs during the age of industrialization between 1850 and 1920 which were experimented on roads and railroads. While most of them were used rarely and have long since been extinct, like the Kellogg truss bridge which was used on the Philips Mill Bridge in Floyd County, Iowa, there are some unusual bridge types that were used and whose examples still exist today, like this bridge.

The Muchakinock Creek Bridge, located in Mahaska County, Iowa between Oskaloosa and Eddyville, carries the Union Pacific line on a single track and is one of a handful of through truss bridges whose design is rather unique for a short-span crossing. Built in 1901 by the Phoenix Iron Works Company of Phoenixville, Pennsylvania, the bridge features a V-shaped truss design that is subdivided diagonally and for the center panels, horizontally. It is classified as a Warren through truss, though when looking at it closely, it could be perceived as a Pratt through truss with subdivided connections. Even weirder is the upper chord of the through truss span, where instead of featuring sway bracings resembling a Howe truss design, it features bracings resembling the subdivided kingpost truss bridge, similar to the one located at Schonemann Park south of Luverne, Minnesota.  A diagram produced by John Marvig shows the unusual configuration:










Two of the four known bridges that are built using this unusual truss configuration are located along this line. The other two are located over Miller Creek in Monroe County along an abandoned railroad. It is obvious that this truss type was used for short crossings as each bridge averaged four panels and 110 feet in length. But it is unknown not only how many were built between 1890 and 1920 and how many more exist beyond the ones found in Iowa so far.

Example of a bridge of a similar design that existed near Manly in Worth County, Iowa. Photo courtesy of John Marvig

The fabricator, Phoenix Iron Works was famous for its unusual bridge designs, as it constructed the longest viaduct in the world using another unusual truss type, the Fink truss, over Lyon Brook in Chenango County, New York, in 1869. The 830 foot long bridge survived only 25 years and was known infamously for deaths and other haunted stories that occurred there. It was also famous for truss bridges built using the Phoenix column, end posts were built using octagonal sides, as shown in this picture. This contributed to the company producing a spin-off in the Phoenix Bridge Company, which existed from 1883 until 1962 and was responsible for building many key bridges, including the Manhattan Bridge in New York City and the Walnut Street Bridge in Harrisburg, Pennsylvania. The Iron Works has ceased production in Phoenixville since 1984 but the facilities are being transformed into other uses including designating some as historic sites.

For many reasons, the Chronicles needs your help. If you know of any bridges that feature similar designs like the ones found in Iowa as well as the dates of construction, etc., please send a line and provide the information. These unusual bridge types are important parts of the history of America’s infrastructure and many of them have a chance to become a historical landmark, as well as a key component to bike trails that will be developed over the next few years, including the crossings along Miller Creek in Monroe County.  Send your info and comments to or drop them off in the Comment section as well as on facebook. History is important and many of these artefacts deserved to be recognized for their unusual designs and the builders who developed them in the first place. That is what the Chronicles is there- research, preserve and teach to future generations about bridges and their role in architectural and transportation history.