Kentucky 1804 Bridge, Spanning Clear Fork Creek, Saxton

Source document Quoted word for word from HAER KY-51. Not written, edited or summarised by this site.

Jayne c. Henderson KY BRIDGE HAER No. (page 2) The KY Bridge over Clear Fork Creek in Whitley County is eligible for listing in the National Register of Historic Places. It is a rare example of a combination of Warren and Pratt trusses, which makes it a good example of the changes and development that occurred in truss technology in the early twentieth century. The KY Bridge is located approximately two miles north of the Kentucky/Tennessee state line and miles southeast of the intersection of US 25 and KY at Saxton, in Whitley County. KY is a two-lane state route connecting Saxton and Fairview. Clear Fork Creek is a tributary of the Cumberland River. The Clear Fork Creek Bridge is a one-lane metal truss bridge with a width of feet and length of 276 feet.

The current structural and appraisal (SIA) rating on the existing bridge is out of a possible 100 points, and the bridge is posted for a weight limit of five tons. According to the bridge plate, the structure was built in by the Champion Bridge Company of Wilmington, Ohio. The Champion Bridge Company was active in Kentucky from to The Clear Fork Creek Bridge demonstrates the evolution of bridge truss technology. The main span is a 150 foot camelback Pratt truss which is flanked by two 60 foot sections of Warren pony trusses. The Warren truss, first patented in is characterized by ,,, its diagonal web pattern and is triangular in outline, with the diagonals carrying both the compressive and tensile forces. A KY BRIDGE HAER No. (page 3) "true" Warren truss has equilateral triangles.

In the Clear Fork Creek Bridge, the Warren trusses are supplemented with verticals and outriggers which serve as braces for the triangular web system. The Warren trusses of the Clear Fork Creek Bridge are called pony trusses because they lack the top lateral bracing. Pony trusses are used for economical reasons when the requirements of weight and length of a particular bridge can be met with short spans of limited weight capacity. The diagonal web members of the truss are alternately placed in compression and tension as the load passes. The camelback truss used in the Clear Fork Creek Bridge retains the Pratt configuration of compression and tension, while changing the shape of the top chords.

This polygonal shape provided greater strength and longer spans than were possible with the Pratt through truss. The Clear Fork Creek Bridge is the only carnelback truss bridge in the state built by the Champion Bridge Company to utilize die-forged eyebars instead of loop-welded eyebars. The Clear Fork Creek Bridge is the only surviving example of a combination of Pratt camelback and Warren pony trusses in the state of Kentucky. As an illustration of the evolution of twentieth century bridge technology, its significance lies in the integrity of its design, materials, and workmanship.