This small ten panel bridge is one of the most unusual and important bowstrings in Iowa, which is really saying something because Iowa has a relatively large number of very significant bowstring truss bridges compared with most states. An example of an unusual patented bowstring design, this bridge is an extremely old metal bridge that is further significant for its use of cast iron connection assemblies. It also includes chords composed of parallel wrought iron pipes, which is an extremely unusual design feature. It is also a rare example of a bowstring truss built by a smaller regional bridge company rather than a large, more prolific company like Wrought Iron Bridge Company. The Moneek Bridge was built very similarly to a design patented by Oliver Perry and William Allen of Beloit, Wisconsin, who ran the Allen, McEvoy and Company also of Beloit, Wisconsin which fabricated this bridge. The company called this patented bridge design a "Eureka Bridge" which is where the alternate name for the Moneek Bridge comes from.
The top chord connection assemblies advertise the patent for this bridge, by displaying PATD on one side and OCT 24 1872 on the other. Technically speaking however, this bridge does not directly follow the items for which the issued patent describes. Looking at the original patent claimed on these cast iron connections, it is clear that this bridge is very similar in design, but at the same time it is apparent that the Moneek Bridge does not truly follow the details described in the patent. Further, the patent was actually issued in 1871, and as such the date appearing in the casting could be a typo! 1872 is however when the Moneek Bridge itself was fabricated.
Assembly identification numbers can also be found on the cast iron connection assemblies.
The bridge is historically and technologically significant as an early patented metal bridge design that reflects the spirit of experimentation that occurred during this period in history as bridge engineers worked with metal as a bridge material.
This bridge was preserved by relocating it to a small park in Castalia. No work was done on the bridge structure, however as a cast and wrought iron bridge not being subjected to salt, paint is not needed on this bridge, and indeed it remains without paint and in decent overall shape except that a number of the cast iron connection assemblies have cracked and in some areas fallen away. Future preservation work could include repairing these cast iron assemblies. While the repair of cast iron has traditionally been considered problematic, recent restoration work on the part of Vern Mesler has proven otherwise.
Bowstring truss bridges are sometimes called bowstring arch bridges because they have similarities to both structure types. Beginning with Squire Whipple's Whipple Arch Bridges, such as the Ehrmentraut Farm Bridge, the bowstring truss bridge is the bridge type that began a transition away from wood and stone and began to make metal a common bridge building material. It also began a period of experimentation until a good bridge form was developed, leading to a gradual standardization of bridge design. During this period, numerous bridge companies all experimented with metal, trying to design the best bridge. Each company had their own distinctive bowstring design, including unique and creative design details. These designs were often patented. Most bowstring truss bridges were built in the 1870s. Also during this time, cast iron was still used in addition to wrought iron for the construction of bridges, so many bowstrings built during this period include details such as connection assemblies that are made of cast iron. By the 1880s, bridge companies decided that the pin-connected Pratt truss was a better structure type, and construction of bowstring bridges sharply dropped after 1880. Because of the period in which Iowa was first being settled, a much larger number of bowstring truss bridges were built in the state than in other states. As a result, even today, Iowa has more historic bowstring truss bridges than any other state, although the number of bridges statewide is under 20, a very small number. However, a number of states do not have even a single historic bowstring truss within their borders. As such, while bowstring truss bridges are very few in number in Iowa, they are extremely rare on a national scale. It is imperative that each surviving bowstring in the county be preserved to protect this key period in bridge building history.
Historic American Engineering Record created a large and very informative historical overview and context for Iowa's bridges, and it is offered here by HistoricBridges.org in convenient PDF format for easy printing or offline viewing. The HAER source for the documents composing the PDF is here.View Historic American Engineering Record's Structural Analysis of Iron Bowstring Bridges (PDF)
Historic American Engineering Record created a large and very informative structural analysis of how bowstring truss/arch bridges function. Everything from basic discussion of the engineering behind the bridges to advanced mathematical equations are available. The HAER source for the documents composing the PDF is here.
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