Scottwood Road Bridge

Information and Findings From Ohio's Historic Bridge Inventory

Setting/Context

The bridge carries a 2 lane road over a stream in a sparsely developed, rural setting.

Physical Description

The 1 span, 45'-long, pin-connected Pratt pony truss bridge is traditionally composed of built-up compression members and eyebar tension members. It has U-shaped hangers for the rolled floorbeams. It is attributed to the Wrought Iron Bridge Co based on the bearing plate and exposed threaded ends of the end panel diagonals that is a telltale design of their early pony truss bridges. Those details are boxed with covers on this bridge. The bridge is supported on ashlar abutments.

Integrity

Appears to have integrity.

Summary of Significance

The pin-connected Pratt pony truss bridge is dated 1905 by the county, but it appears to be a ca. 1882 Wrought Iron Bridge Co. product given that it has their telltale connection detail at the upper panel point where the inclined end post meets the upper chord. The design, with its distinctive upper chord panel point connection details, is characteristic of their pony trusses dating from the mid 1870s to early 1890s. The design is described as "very popular" and having been built widely in an 1881 WIBC catalogue. The bridge also has the rolled "beaded T" section for the verticals, another feature of WIBC. The design was intended to make a stiffer section. There are at least 13 very similar extant examples of this very design dating from 1874 to the early 1890s, and it is the early ones that are significant.

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design of the last quarter of the 19th century and continued to be built into the 20th century, although eventually superseded in popularity by Warren trusses.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

Bridge Considered Historic By Survey: No