This bridge was built in 1899. It is a two span pin connected
Pratt through truss bridge. Each bridge is composed of seven panels. There is
v-lacing on the vertical members, under the top chord / end post as well as on
the sway bracing. The portal bracing is a lattice design. The bridge sits on
stone piers and abutments. There is a stone
arch bridge just east of this bridge.
HistoricBridges.org is happy that this bridge was not demolished when it was bypassed by a modern bridge on a new alignment to the south in 1970. Leaving the bridge standing has allowed the bridge to stand to the present day as a
historic landmark. At the same time, it is sad to see that this bridge, which is surrounded by a rustic park on the east side of the bridge, has not been restored for pedestrian use. It is instead fenced off. The stone pier is beginning to
show scour problems. It would be nice to see the pier repaired and the bridge superstructure and deck repaired to allow the bridge to open to pedestrians. The park is currently just a dirt drive with a few trails in the woods. The bridge
could function as a scenic outlook for park visitors, as well as a fishing pier. It would make the park more than the small set of unimproved trails that it currently is. The park would be a destination for people to experience the historic
bridge. There could be informational signs set up for the bridges.
Information and Findings From Ohio's Historic Bridge
The bridge is closed to traffic. It is in a public park (Blankenship Park) but apparently unmaintained.
The 2 span, pin-connected Pratt thru truss bridge is lightly built and appears from photos to be traditionally composed.
Summary of Significance
The 1899 pin-connected Pratt thru truss bridge, which had already been bypassed, was determined eligible by the SHPO in 1977 and it was also select in ODOT's 1981 survey. A copy of the survey form is on file at
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design of the last quarter of the 19th century and continued to be built into the 20th century, although eventually superseded in popularity by Warren trusses.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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