By 1872, the Des Moines, Winterset & Southwestern Railroad Company built a line from Summerset Junction to Winterset, Iowa.
These two railroads remained independent until 1876, when both were purchased by the Iowa Southern & Missouri Northern Railroad Company.
The IS&MN was eventually consolidated into the Chicago, Rock Island & Pacific Railroad Company in 1880.
The Rock Island was a poor Railroad, often times in financial issues. The branch from Summerset Junction to Winterset was abandoned in 1958.
By 1980, when the Rock Island finally went bankrupt, the Chicago & Northwestern purchased much of the core lines through Iowa.
The Chicago & Northwestern was absorbed by the Union Pacific in 1995.
The line to Indianola connected to the core line at Carlisle. While the Chicago & Northwestern used the line towards Indianola, it was not critical and was abandoned in 1998.
Soon after it was turned over to Warren County to be built as the Summerset Trail, which is its current purpose.
06/26/21
Located near Carlisle, this small pony truss bridge crosses the Middle River.
Built in approximately 1900, the bridge features a unique 10-panel riveted Warren Pony Truss. This span is approached by trestle and set onto timber substructures.
Much about this span is unknown. It is likely that this span was relocated to this location. The span itself is unique, as it follows a standard Warren pattern, instead of a more common Pratt or Double Intersection Warren design. The span is also fairly long, although consists of 10 short panels. A typical pony truss will have four to eight panels.
Northern Pacific built a number of spans similar to this, and those date to 1895 to 1900. Rock Island was only known to have built a very small handful of pony trusses, and very few remain. This one appears to be entirely unique.
Currently, this bridge is used by the Summerset Trail. The bridge is located near Banner State Park. Unfortunately, not much on the history of this bridge can be found.
Overall, the bridge appears to be in good condition, although the piers probably should be replaced with concrete to prevent flood damage.
The author has ranked this bridge as being regionally significant, due to the unusual design. Short, girder-like Warren pony trusses are uncommon in the midwest and this is one of only a handful in the region.
The photo above is an overview.