The Red Bridge is a remnant of the Carrieton-Orroroo railway line. Erected in 1882, it was opened prior to that railway being completed. It was built to cross the town's Pekina Creek. Although much of the rail has been pulled up, the structure still stands today as a tribute to bridge engineering of the 19th century.
Looking for the bridge might be a little tricky if you've not been to Orroroo before. With websites not stating its exact location, I had to trace it down via Google Maps. The bridge can be found between R M Williams Way and Arthur Road northwest of the town centre. From Orroroo, take the main route to Carrieton and turn left just before reaching Slaughterhouse Road.