Oregon 19, J9S3219, Bridge H0289—Thayer Viaduct, Highway 19 (BU 63) over Two Mile Creek
The Thayer Viaduct is a 1930, pin-connected eight-panel Pratt through truss with two rigid-connected six-panel Warren pony truss approach spans on the north end. The bridge has a total length of 305 feet, with a main span of 155 feet and 74- and 75-foot long approach spans. The bridge has a 20 foot wide roadway. A 5 foot wide sidewalk cantilevered on the east side of the bridge was added in 1947. The sidewalk has a chain-link fence barrier.
The bridge has concrete abutments with wingwalls and concrete pier bents with concrete web-walls.
The bridge is eligible for the NRHP under criteria A and C for significance in transportation and engineering. The Thayer Viaduct was cooperatively built by the Missouri State Highway Department and the Frisco Railroad during a time when an effort was being made to reduce at grade crossings to improve highway safety. The cost of the viaduct was shared between the two parties and the federal government. The through truss was designed by the Frisco Railroad and reflects structural features common for both highway and railroad trusses of the era. The pony truss approach spans were standard Missouri State Highway Department designs.
