reverse curve on an interurban near Shawnee, Oklahoma

Or an S curve as it is also known; a feature that model railroaders like to add as it is more interesting than a straight line.

It's not clear exactly what line this is; there was an Oklahoma City-Shawnee Interurban which was purchased by the Oklahoma City-Ada-Atoka Railway in May 1930 and in 1964 sold to the Santa Fe. There was also the Shawnee-Tecumseh Traction which ran 6 miles (10 km) between these two places from September 1906 to January 1927 when it was replaced by buses.