The Knickerbocker Spur
This short (~1 mile) spur was built in the 1880s by the Pennsylvania Railroad and served two purposes: It provided the PRR with an interchange with the Reading Railroads Chester Valley Branch (also abandoned), and it served the Knickerbocker Quarry near Frazer, PA. The entire spur was removed sometime in the 1940s. The only evidence that remains of the line today is a lone bridge pier on Conestoga Road (pictured).
Thanks to Joe Sharretts for contributing information.
Thanks for posting this - I never knew about this line!