CR-21 Bridge

Information and Findings From Ohio's Historic Bridge Inventory

Setting/Context

The bridge carries 1 lane of a 2-lane road over a stream in a rural area of active farms.

Physical Description

The 1 span, 143'-long, Whipple truss bridge is composed of built-up compression members and eyebar or rod tension members. There is lattice portal bracing with builders plaque.

Integrity

Issues that may effect long-term preservation include geometry because the bridge is located on a curve. It also has a vertical profile that limits sight lines.

Summary of Significance

The 1882 truss bridge is a technologically significant example of the double-intersection Pratt thru truss by a prominent Ohio fabricator, the Massillon Bridge Co. It is an extremely good example of its type and design and was fabricated by an Ohio bridge builder. Double-intersection Pratt trusses, also known as Whipple trusses, were among the most successful of long-span thru truss designs (up to 300' long) of the 1860s until about 1890 for both railroad and vehicular crossings. Surviving examples are uncommon nationally and considered technologically significant; Ohio with at least 14 identified examples dating from 1881 to 1898 (Phase 1A survey, 2008) has a very high number in comparison to most other states. The truss design is characterized by diagonals that extend over two panels. In 1847, Squire Whipple, one of America's foremost bridge engineers, developed the design figuring that the double-intersection configuration increased the depth of panel without altering the optimal angle of the diagonals, thus allowing for increased span length. His design was further refined in 1859 by John W. Murphy, the talented chief engineer of Pennsylvania's Lehigh Valley RR, who substituted wrought-iron pins for cast-iron connecting pieces, thus developing the connection detail that would prove to be advanced construction practice for this and other truss designs for the next several decades. Ohio's surviving examples, which mostly date to the 1880s, were not cutting edge for their time, but they show how the form had evolved into the preferred long-span thru truss design of the period. Most have documented associations with prominent Ohio-based fabricators. They also have ingenious details that reflect idiosyncratic thinking that is reflective of the era of experimentation in metal truss bridge design.

Justification

There are 13 examples of the bridge type important to the development and maturation of the pin-connected thru truss bridge. They date from 1881 and concentrated in the 1880s. Even though there are more than 12 extant examples in Ohio, each built in the 1880s has high significance based on overall scarcity (everywhere but in Ohio) of the design. This is a major and technologically significant bridge type. The bridge has high significance.

Bridge Considered Historic By Survey: Yes