The townsite of Cassandra had 2 separate roadbeds curving through, the New Portage line occupied what is now Portage Street. It was built in 1855, 1 year after the original line of the PRR was built just to the east. The NPRR was abandoned in 1858 by the PRR, their original line lasted until 1898, when the current PRR/PC/NS main was built on a series of cuts and fills, eliminating the S-curves of PRR's original line from Lilly to Portage.
The current fire station in Cassandra is built on x-PRR grade, this original grade is also the Ben'sCreek branch between Sonman and Portage.
The Allegheny Portage roadbed and Plane #3 between Lilly and Cassandra is now occupied by PA RT 53.
With no less than 4 intertwining roadbeds through this area of the West slope, it can be hard for a casual observer to understand.
This book explains with maps/photos far better than I can...