The bridge is also significant in documenting one of the most unusual bridge companies in the country, the Columbia Bridge Works of Dayton, Ohio, which when this bridge was built didn't even go by that name yet, and was simply a small company run by the founder of the Columbia Bridge Works, David H. Morrison. David H. Morrison's company which later became the Columbia Bridge Works was noted for defiantly avoiding the period trends in terms of bridge details. Its bridges almost always have very unusual details, and oddly, their bridges tend to have a somewhat modern look to them. This is partly because the company seems to have preferred simpler truss members: for example, where other bridge companies used built-up beams with v-lacing and lattice; Columbia Bridge Works might have used rolled beams.
This bridge is a great example of this. Typical 1870s wrought iron bowstrings by other bridge companies would have used built-up beams for top chord, including unusual patented columns with complex designs, etc. Yet this bridge by Columbia Bridge Works uses simple rolled i-beams.
This is the only known example of this variety of Columbia Bridge Works bowstring, however one earlier cast iron bowstring by the company's founder David Morrison remains at New Bremen.
Ever wonder why HistoricBridges.org has so many photos of each bridge, and why there is a focus on the details of a bridge? Because the details, especially on a bridge like this, are truly interesting and suprisingly can have a lot of complexity to them. Also, sometimes the details tell a story. It is obvious that 19th Century bridges were built of quality materials and design that is vastly superior to modern bridges. Modern bridges built in the 1960s are falling apart and being replaced across the country. Yet this bowstring built decades before motor vehicles were even invented remains in use today. At the same time, there was no OSHA and workers might have got away with things they wouldn't today... perhaps a little alcohol consumption on the job? One of the details noted on this bridge was at a splice for the lattice railing. It is clear that whoever drilled the holes for the rivets put them in the wrong spot the first time and had to do it a second time! There are secondary unused holes overlapping the actual holes occupied by the rivets!
The bearings were buried in dirt during the 2014 field visit. Failing to send someone with a shovel and broom out annually to clean dirt away from bearings can cause deterioration that can lead to thousands of dollars of repairs. Its a simple job to remove dirt, and can be done by day labor... and as road work goes, isn't all that labor-intensive for the people sent to do the work. It makes sense to keep bearings clear of dirt. It doesn't make sense to let dirt build up to the point that healthy grass is taking root.
The Mallaham Bridge is slated to be rehabilitated in 2016. This is great news given the high significance of the bridge!
Information and Findings From Ohio's Historic Bridge Inventory
The bridge carries a 1 lane road over a stream at a Y intersection in a sparsely developed, rural setting.
Bridge maintains integrity. It is posted for 5 tons. Bearings are buried in dirt and need to be cleaned. Their present condition is inducing rust. The patches on the abutments are not holding.
Deck replaced in 1988.
Summary of Significance
The1871 bridge is a very technologically significant and rare surviving example of David H. Morrison's patented bowstring truss. Bowstring trusses are characterized by arched top chords and a trussed or lattice web. They rank among the rarest and most technologically significant of 19th-century metal truss designs since they appeared early in the evolution of iron bridge development and were almost always based on the patents or proprietary designs of bridge builders and engineers. The progenitor of the form was the famed engineer Squire Whipple of New York, who built the first example in 1840 over the Erie Canal at Utica. After the Civil War, Ohio was a center for the development of the bowstring with its concentration of metal bridge-building companies. Companies such Wrought Iron Bridge, Champion Bridge, Massillon Bridge, and King Iron Bridge built their reputations on successful bowstring designs with a dizzying number of variant ways of forming and connecting the truss members. The companies emerged in time to fill the burgeoning demand for an economical, prefabricated bridge for use on American roads. Bowstring trusses thus document this exceptionally inventive and technologically significant period in the development of American metal trusses from the 1860s to early 1880s. The ODOT inventory has identified 22 surviving examples dating from ca. 1864 to 1880 (Phase 1A, 2008).David H. Morrison, founder of the Columbia Bridge Works, was among the earliest and most influential truss bridge builders in Ohio. Morrison began building wood bridges in 1848 and received a patent for an iron bowstring design in 1867. The Morrison bowstring made use of I-beams laid on their sides to form the arch. This detail was carried through to later truss designs, like the Whipple and the Pratt, where Morrison used I-beams to form compression members for the upper chords and verticals. These bridges anticipated the simple pin-connected designs of the 1890s but still retained many transitional details such as cast-iron connecting pieces and spacers. About 1867 Morrison formally established the Columbia Bridge Works in Dayton. His son, Charles C. Morrison, joined the company a few years later. The Columbia Bridge Works went out of business about 1890.
The1871 bridge is a very technologically significant and rare surviving example of David H. Morrison's patented bowstring truss. Because it is rare, it is a high priority.
Bridge Considered Historic By Survey: Yes
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