This bridge is apparently still capable of carrying the local traffic as the above photo shows. Although it does not retain original railings, and the abutments do not look original, this bridge is an attractive structure
that adds interest to this rural agricultural landscape. The bridge features four panels, lattice on the vertical members, and v-lacing under the top chord and end post. As of 2013, this was one of the few metal truss bridges in Wood County
not yet demolished. This bridge was not so long ago one of many.
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 60'-long pin connected Pratt pony truss bridge appears to be traditionally composed.
Summary of Significance
The one span pin connected Pratt pony truss bridge was moved to its current location in 1941. Its date of construction is not documented in county file, but it was Br. #4 on Road 23-A in Jackson Twp. The bridge
is traditionally composed and has no distinctive features or details. 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quarter of the 19th century and continued to be built into the 20th century, although eventually superseded in popularity by Warren trusses.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.
A collection of overview and detail photos. This photo gallery contains a combination of Original Size photos and Mobile Optimized photos in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer