Pyrmont 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 rural area of active farms.

Physical Description

The 1 span, 180'-long, pin-connected Camelback thru truss bridge is traditionally composed of built-up compression members and eyebar tension members. It has A-frame portals but the builders plaques shown in 1980s ODOT survey photos are no longer present.

Integrity

New galvanized corrugated deck, 1995.

Summary of Significance

The 1904 pin-connected Camelback thru truss bridge is a complete example of its type/design. This bridge type/design was developed in the 1870s and 1880s, so it is not an early example in the evolution of the technology, but it is the oldest surviving example in the Ohio inventory. There has been no change in the bridge's status since the prior inventory. The eligible recommendation remains appropriate.

Camelback and Parker trusses are members of the Pratt-family of trusses with sloped top chords Technologically, Camelback and Parker trusses differ only in the number of top chord slopes (Camelbacks have exactly five slopes, and Parkers have more than five slopes.) The sloped-chord trusses provide the greatest depth at midspan where it is needed to accommodate the stresses, meaning that less material is needed in their construction as compared to a parallel chord truss of similar span, but fabrication is made more difficult due to the varying lengths of the members. The sloped-chord trusses are often associated with longer spans where the savings in material is great enough to be worth the additional fabrication costs. The practice of sloping the top chords dates to at least the 1840s and appeared early in the development of metal trusses. As with other truss designs, pin connections were used from the 1870s to 1900s, and mostly phased out during the 1910s. Rivet connections were being used by the early 1900s and were prevalent from the 1910s to 1940s. Standardized rivet-connected Camelback and Parker designs were used by many state highway departments, including the Ohio State Highway Department. There are 23 trusses (8 Camelback, 15 Parker) in the Ohio inventory (Phase 1A, 2008).

Justification

The pin connected thru truss bridge is one of 13 extant examples of bridges with polygonal upper chords and/or subdivided panels in the state that date from 1888 until 1923. It is of moderate significance given that the numbers in the population.

Bridge Considered Historic By Survey: Yes