This bridge is a relatively late example of a traditional
truss type. It retains excellent historic integrity including original
railings. It has rusted however, and now would be a great time to preserve
this bridge with a sandblast and painting project. Such a project would also
be a good time to sensitively repair this historic bridge to correct any
deficiencies. Smaller truss bridges like this one are attractive
preservation targets because they do not cost as much to preserve.
Information and Findings From Ohio's Historic Bridge
The bridge carries a 2 lane road over a stream in a sparsely developed, rural setting.
The 1 span, 60'-long, rivet-connected Pratt pony truss bridge is composed of built-up members and has lattice railings. It is supported on concrete abutments.
Summary of Significance
The 1934 Pratt pony truss is a late example of its type/design with no distinguishing features. It has riveted connections, typical of trusses from about 1900 to the 1940s when riveted connections began to be
phased out in favor of welded connections. This example is not historically significant for its technology or context. More distinguished examples better represent the significance of the type/design in the development of the
state's road systems. The not eligible recommendation of the prior inventory remains appropriate.
Pratt trusses were undoubtedly the most popular truss design of the last quarter of the 19th century and continued to be built
into the 20th century, although eventually superseded in popularity by Warren trusses. The design, which initially was a combination of wood compression and iron tension members, was patented in 1844 by Thomas & Caleb Pratt. Ohio
has three covered bridges that use this combination configuration, but they are all modern reconstructions based on the Pratt patent. The great advantage of the Pratt over other designs was the relative ease of calculating the
distribution of stresses. More significantly, it translated well into an all-metal design in lengths of less than 200'. Significant surviving examples of all-metal Pratt trusses mostly date to the last quarter of the 19th century,
and they are found with thru, pony, and the less common bedstead configuration. Prior to about 1890, a variety of panel point connections were in widespread use (including bolts, cast-iron pieces, and pins), but engineering opinion
was coalescing around pins as the most efficient and constructible. Many of the connection details were proprietary and associated with individual builders or companies, and thus earlier examples are generally taken to be
technologically significant in showing the evolution of the design. Later post-1890 Pratt trusses show a progression toward less variation in their details such that by 1900 the design was quite formulaic with few significant
differences between the designs of various builders. This marked the end of the pin-connected Pratt's technological evolution and, in fact, it was soon waning and eclipsed in the highway bridge market by more rigid, rivet-connected
truss designs, particularly the Warren but also riveted Pratts. The transition to riveted connections, which happened even earlier with railroads than highways, was in no small part due to concerns about stress reversals at the pins
under heavier loads and improvements in pneumatic field riveting equipment in the early 1900s. In Ohio, Pratt truss highway bridges, whether pinned or riveted, were almost always built under the auspices of counties and local units
of government; the Pratt was not a standard design of the state highway department.
In Ohio, there are 185 Pratt trusses dating from ca. 1874 to 1945 with at least 60 dating prior to 1900 (Phase 1A, 2008). The
technologically significant unaltered examples of pin-connected Pratt trusses for the most part date prior to 1900 and have documented or attributed builders and dates of construction and/or significant connection or member details.
Later post-1900 examples are less technologically significant. Significant unaltered examples of riveted-connected Pratt trusses date from ca. 1900 to 1915.
Bridge Considered Historic By Survey: No
Photo Galleries and Videos: Platter Creek Road Bridge
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Maps and Links: Platter Creek Road Bridge
This historic bridge has been demolished. This map is shown for reference purposes only.