North Creek Bridge

Information and Findings From Ohio's Historic Bridge Inventory

Setting/Context

The bridge carries a nearly abandoned 1-lane road over a stream in a sparsely on the edge. The road passes through corn fields.

Physical Description

The 1 span, 40'-long, cast- and wrought-iron, pin connected Pratt truss is an early example of its type. The end posts, upper chords, and verticals are rolled I section, and the lower chords are spliced sections of plate. The diagonals and counter are rods with eye or upturned ends. The verticals are connected to the lower panel points with cast iron castings, and block-like cast connecting pieces are used for the diagonals that pass through the upper chords. The bridge is remarkably complete.

Integrity

The bridge retains integrity.

Summary of Significance

The pin connected pony truss bridge dated to ca. 1875 appears to be the design of David H. Morrison and the Columbia Bridge Works. The members are similar to his better-known bowstring bridges like 6932509. It is technologically significant example of the Pratt pony truss type/design exhibiting proprietary details that document the transition from the cast- and wrought-iron trusses of the mid-19th-century to the standard pin-connected steel trusses of the late 19th century and early 20th century (Criterion C). David H. Morrison, founder of the Columbia Bridge Works, was among the earliest and most influential truss bridge builders in Ohio. Morrison began building wood bridges in 1848 and received a patent for an iron bowstring design in 1867. The Morrison bowstring made use of I-beams laid on their sides to form the arch. This detail was carried through to later truss designs, like the Whipple and the Pratt, where Morrison used I-beams to form compression members for the upper chords and verticals. These bridges anticipated the simple pin-connected designs of the 1890s but still retained many transitional details such as cast-iron connecting pieces and spacers. About 1867 Morrison formally established the Columbia Bridge Works in Dayton. His son, Charles C. Morrison, joined the company a few years later. The Columbia Bridge Works went out of business about 1890. The ODOT inventory has identified at least six metal-truss bridges dating from ca. 1880 to 1887 attributed to the Columbia Bridge Works (May 2009).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'. 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. 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.

Justification

The bridge is of high significance because it is important in moving from bowstring to the standardized design pony truss Pratt type and design. It is also attributed to one of the most important early fabricators in the state.

Bridge Considered Historic By Survey: Yes