The Wilkes T. Thrasher Bridge is a 4-lane road bridge located in Chattanooga, Tennessee.[1] It opened in 1955 as a two lane road after much pressure from Wilkes T. Thrasher, a prominent Hamilton County Judge, to the Federal Government. In the 1980's, the bridge was widened to four lanes. Traffic was rerouted via the neighboring C.B. Robinson Bridge carrying State Route 319 (Du Pont Pkwy) and carries Tennessee State Route 153 over the Chickamauga Dam crossing the Tennessee River. The bridge is highly unusual, Not only was it built directly on top of a dam, but it was built many years after the dam was built. A number of dams include bridge-like structures on them, that may be just for dam maintenance or may carry an actual highway. Typically however such structures are built at the same time as the dam. The Chickamauga Dam was built from 1936-1940. The bridge however was not built until 1954. The highly unusual design soars high above most of the dam to accommodate the height of the power house which it also passes over, and also to allow for maintenance vehicles on the dam below. Most structurally significant about the bridge itself are that many of the spans utilize a steel rigid-frame design. Steel rigid-frame bridges, particularly from the pre-1970 era when rivets were still used are extremely rare. Other spans on the bridge appear to be more traditional simple riveted deck plate girders and steel stringers.
