Raccoon River Valley Trail - Bay Branch Bridge

Located on the east side of Panora, this deck plate girder bridge carries a former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) branch line over Bay Branch. The first bridge at this location was likely a timber pile trestle bridge, constructed when the line was first built. In 1892, the original bridge was rebuilt with a 55-foot iron deck plate girder span, set onto steel cylinder piers and approached by timber pile trestle. By the mid-20th Century, this bridge had become too light for modern railroad traffic. In the early 1940s, the Milwaukee Road invested significant capital into this line, replacing aging iron bridges with secondhand steel spans set onto new concrete piers. In 1944, the bridge was rebuilt with a secondhand deck plate girder span, set onto two new concrete piers. At this time, the original approach trestles were rebuilt, giving the bridge its present configuration. Currently, the bridge consists of a 55-foot deck plate girder span, set onto concrete piers. The north end of the bridge is approached by three timber pile trestle spans, while the south end is approached by two timber pile trestle spans. All of the approach spans are set onto timber pile substructures, except for the northern bent of the south approach, which is supported by a timber bent set onto a steel cylinder pier from the previous bridge.

The deck plate girder span does not follow a standard design, and instead consists of an extensively modified structure with two heavy plate girders, heavy internal bracing and an open deck. This span was originally fabricated in 1897 for use as part of a three span structure at Bridge #Z-1284, which crossed Brushy Creek Bridge near Dedham, Iowa. Originally, the span was configured as a 65-foot type "C-3" through plate girder span. When that span was replaced by the present double track bridge in 1914, the three spans were reused at various locations. The 65-foot center span was reused at Bridge #T-598, which crossed the Big Sioux River north of Hudson, South Dakota. That bridge was replaced by the current bridge in 1932, and the 65-foot girder span was shipped to the bridge shop at Tomah, Wisconsin. The span was then modified by removing the original rounded ends and floor system, and converting the span to a deck plate girder span for reuse at this location. The concrete piers use a standard design, consisting of a rectangular shape with rounded ends. Wisconsin Bridge & Iron Company fabricated the girders, while it is believed railroad company forces modified the span and converted it to a deck plate girder. Railroad company forces also constructed the timber portions of the bridge, and it is unclear if the concrete piers were constructed by railroad forces or by an unknown contractor. Railroads often reused steel spans, as it was a cost effective way to upgrade bridges without requiring large amounts of new material. Often, when a span was no longer adequate for mainline use, it could feasibly be reused on a branch line with or without alterations. Deck plate girder spans were popular for railroad use, as they were durable and easy to construct. After abandonment, a concrete deck was added to the bridge and wooden railings were installed. Today, the bridge continues to carry the Raccoon River Valley Trail, a popular multi-use trail in Central Iowa. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being locally significant, due to the common design.