This was a four panel structure that retained a good deal of
historic integrity, despite being closed to traffic. The bridge retained original
lattice railings. Vertical members featured lattice, and v-lacing was present
under the top chord and end post. The small size of this bridge would have made this
a good, inexpensive candidate for restoration. The bridge sat on attractive
stone abutments. Like most historic truss bridges in Wood County, this bridge has since been demolished, a clear indication of the rather limited interest in preservation found in the county.
Information and Findings From Ohio's Historic Bridge
The bridge carries a 2 lane road over a stream in a rural area of active farms.
The one span pin connected pony truss bridge appears to be traditionally composed. It is supported on ashlar abutments. Do not know what was done to it in 1936.
Bridge closed, sprung LC, broken upper panel point connection.
Summary of Significance
The bridge is has some failing members, and county records do not have date, just fabricator. Less altered and more distinguished examples of this bridge type and this fabricator exist in the region and state.
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design of the last quarter of the 19th century and continued to be built into the 20th century, although eventually superseded in popularity by Warren trusses.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.
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.
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Maps and Links: Mitchell Road Bridge
This historic bridge has been demolished. This map is shown for reference purposes only.