Precht Bridge

Information and Findings From Ohio's Historic Bridge Inventory

Setting/Context

The bridge, which is closed to traffic, provides access to the rural Showman-Edward Cemetery in Mary Jane Thurston State Park. It is open to pedestrians.

Physical Description

The 1 span, pin-connected Pratt thru truss bridge is traditionally composed of built-up compression members and eyebar or rod tension members. The upper chords are toe-out channels with cover plates and lacing. The verticals are toe-out-channels with lacing. The bridge has lattice portals, and upper lateral bracing of angles with lacing. Rolled floorbeams are supported from the lower-chord pins by U-shaped hangers. The bridge has rolled stringers and wood deck. There are lattice railings. The abutments are ashlar.

Integrity

Some loss of original fabric from metal-related deterioration.

Summary of Significance

The ca. 1906 pin-connected Pratt thru-truss bridge is a later example of its type/design with no distinguishing features or details. It is attributed to the Massillon Bridge Company of Massillon, Ohio, based on its similarity to 24xxxx1, a documented example from 1906. In comparison to the population, the bridge is not distinguished by its history or technology.

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design of the last quarter of the 19th century and continued to be built into the 20th century, although eventually superseded in popularity by Warren trusses.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