Brush Creek Bridge - Baxter Springs, Kansas - U.S. National Register of Historic Places on Waymarking.com

The Brush Creek bridge in Cherokee County is located on a county road 3.4 miles north of Baxter Springs. The 130 foot re-enforced concrete "rainbow arch" (or "Marsh arch") bridge was part of a project in the early 1920's that linked Galena, Riverton, and Baxter Springs with a concrete road. The roadway has been resurfaced periodically but this has not significantly compromised the bridges integrity. Marsh's plans allowed for whatever filling material, between the bridge deck curbs, that locality might desire. Apparently during the bicentennial celebrations of 1976 the bridge was painted red, white, and blue with various patriotic slogans and symbols.

The best description of a rainbow arch span is contained in James Marsh's 1911 patent application. The bridge consists of ". . . two abutments (which could be piers), a pair of arches disposed between and springing from the abutments, the floor carried by and between the arches and reaching from one abutment to the other where it aligns with the parapets or rails along opposite sides of the floor line." The original patents called for slideable wear plates to be moulded into the concrete where the bridge floor came into contact with the beams and abutments. This is of importance as one of the main benefits of this design was to allow for the expansion and contraction of the reinforced concrete bridge under varying conditions of temperature and moisture.

The Brush Creek bridge is 20 feet wide and its arches rise 26 feet. The bridge deck is approximately 22 feet above the low water elevation and approximately 34 feet above the bedrock on which the abutments rest. Completed on December 20, 1923 the structure had a live load capacity of 125 pounds per square foot.

There were two basic rainbow arch designs, fixed and tied. The original patent application describes the fixed type, such as the Brush Creek bridge, in which case the arch flowed below the bridge deck and was "fixed" directly into the abutment. This massive abutment (or pier) resisted both the horizontal and the vertical thrust of the arch. In a tied design the arch did not flow below the deck line and was not fixed directly into the abutment. It was secured atop the abutment or pier by the use of steel rocker or expansion rocker bearings. Vertical thrust was resisted by the pier and bearing, while horizontal thrust was resisted by the addition of a lower chord.