Shaffer Road Bridge

Information and Findings From Ohio's Historic Bridge Inventory

Setting/Context

The bridge carries a 1 lane road over a stream in a sparsely developed, rural setting.

Physical Description

The 1 span, 168'-long rivet-connected Pratt thru truss bridge is supported on concrete abutments. It is traditionally composed of built-up members with toe-out channels with cover plate and lacing for the chords and end posts; back-to-back angles with lacing or channels for the verticals and diagonals; and back-to-back angles with battens for the lower chords. The bridge has lattice portals with builders plaque.

Integrity

Rehabilitated in 2000. Fiberglass deck; strengthening of some members (e.g. adding angle section to lower chords); and some replacement of rivets with high-strength bolts.

Summary of Significance

The 1913 rivet-connected Pratt thru truss bridge is one of four extant examples of the design in the county that were placed to replace ones lost in a flood. All were placed in 1913, which makes them among the earliest in the state. Why there are so few riveted through truss bridges in Ohio, when the technology to do field riveting was common by 1900, is not known. The four in the county are determined to be technologically significant because they are early examples within the Ohio context. It is representative of the standard, riveted, Pratt thru-truss type/design that was popular on Ohio's roads from about 1900 to 1940. The truss superstructure is complete with the exception of some loss of fabric from corrosion. The Massillon Bridge & Structural Iron Company of Massillon, Ohio, was one of the many Ohio bridge-fabricating companies that served the regional market in steel highway bridges during the early 20th century. Its designs of this period are not distinctive in and of themselves but reflect the increasing standardization of detail that was the hallmark of rivet-connected highway truss type/design.

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design of the last quarter of the 19th century and continued to be built into the 20th century, although eventually superseded in popularity by Warren trusses.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. 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'. 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. Significant unaltered examples of riveted-connected Pratt trusses date from ca. 1900 to 1914.

The Massillon Bridge Company of Massillon, Ohio, was a prolific builder of highway truss bridges from the 1870s to 1930s, and is among the best represented of Ohio bridge fabricators in the inventory with at least 27 identified examples dating from ca. 1872 to 1913. The company remained in operation until the Great Depression, when it became a division of the Fort Pitt Bridge Works of Pittsburgh. It closed in 1943.

Justification

The bridge is one of over 40 extant riveted thru truss bridges of all designs built between 1904 and 1959. This example is representative of the population and has moderate significance. There are also many riveted thru truss bridges servicing the many rail lines in the state.

Bridge Considered Historic By Survey: Yes