This attractive through truss is buried away on an abandoned
road. This road used to be the old alignment of US-42 The portal bracing for this
bridge is rather unusual in design. There is v-lacing on the verticals and some
diagonals, as well as one the sway bracing. Lattice railings remain on the
bridge. There are unusual concrete railings leading up to this bridge. "COHAINS GIRKINS" presumably a contractor and "1924" is a
date cast into these unusual concrete railings, which many have assumed is
construction date for the truss bridge as well. However, a close examination of this bridge led to several questions that may indicate the bridge is older than 1924. First, the bridge has built-up vertical members composed of two pairs of
angles with v-lacing. This is fairly lightweight, especially for a 1924 bridge. More common are built-up verticals with back-to-back channels and v-lacing on each side. The most unusual aspect however is found in the struts and overhead
lateral bracing. Facing northeast, an unusual splice occurs toward the left end of the struts. The lateral bracing also is spliced. Typically, long members on a truss, such as the top chord, were frequently spliced together in the field
since they had to be shipped in lengths that were manageable. However, the struts are not long enough to justify needing to be shipped in two segments, especially considering that the splice only allow for a short amount of additional
length. Also, at the splice point, the pattern of v-lacing is interrupted by a batten. There is no reason for this batten to be here, and the only other place that battens are present are at the ends of the struts. This batten next to the
splice also makes the strut asymmetrical in appearance, which is not normal. Long story short, the current appearance of the struts suggest that this bridge was widened. The widening likely occurred in 1924, since a wider bridge would need
new or expanded abutments. It may have anticipated the road and bridge serving US-42, which may have increased traffic on the road, making having a wider bridge prudent. Assuming this theory is accurate, the original bridge may date to ca
Information and Findings From Ohio's Historic Bridge
The bridge is closed to traffic and located on an abandoned section of county road (former US 42).
The 1 span, 89'-long, rivet-connected Pratt thru truss bridge is traditionally composed of built-up members.
Summary of Significance
The 1924 Pratt thru truss is a late example of its type/design with no distinguishing features. It has riveted connections, typical of Pratt 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.
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.
Original / Full Size Photos A collection of overview and detail photos, taken August 11, 2012. This gallery offers photos in the highest available resolution and file size in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer
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A collection of overview and detail photos, taken May 19, 2006. 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