Insley 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, 95'-long, rainbow (thru) arch bridge has flat-paneled arch ribs with floorbeam hangers and articulated floorbeams. Concrete balustrades fill between the hangers, and flat-panel parapets extend between the arch ribs and the wingwalls.

Integrity

Some loss of fabric from spalling.

Summary of Significance

The rainbow arch bridge built in 1930 is a complete, albeit later, example of a bridge type that was in use from the late 1900s to 1930s. The inventory has identified seven surviving examples dating from 1909 to 1930 (Phase 1A Update, 2008). This one, like several others, appears to be the state bridge bureau's design that was in use during the 1920s to early 1930s based on the details.

The rainbow arch in the U.S. developed in the late 1900s and early 1910s, with its best known variation the 1912 patented design of James B. Marsh of Iowa, (which is debatably a steel arch encased in concrete). In the basic design the deck is supported by vertical hangers between the arch ribs and the floorbeams. The arch ribs, like Marsh's can have patented steel systems within them, or they can be un-patented systems of conventional reinforced concrete. The bridge type/design is known to be aesthetically pleasing and came to be popularly known as "rainbow" arches in some parts of the country, including Ohio, although technically they are perhaps best described as thru arches. The bridge type was always more numerous in the Midwest than other parts of the U.S., probably because of the influence of Marsh. The 1909 and 1911 thru arches designed by E. A. Gast in Hamilton County (3137600 & 3130622) are Ohio's oldest examples and very technologically significant as they predate the Marsh patent and are believed to have been developed independently. Later examples in Ohio are most often the design of the state bridge bureau, which developed its own standard rainbow arch by 1923.

Justification

The bridge is one of 5 remaining examples of the type that was once not uncommon in Ohio. It offered an aesthetic treatment preferred in urban and picturesque settings. The 6 examples date from 1909 to 1930, and each is of high significance given their limited numbers and importance within the context as the aesthetic alternative to the thru truss bridge.

Bridge Considered Historic By Survey: Yes