BSS upper level tracks

I've heard mention of upper level tracks on this forum. Can someone explain what they were used for??

I thought the BSS was just a 4 track subway?? I remember back in the 1980's that Septa was ripping up some of the express tracks. Are they still gone or are there indeed 4 tracks from CC to Olney??

It's still a 4-track subway from Walnut-Locust to Olney. The upper level tracks are just north of Erie station. It is just a few storage tracks and was used to turn the Ridge trains around when they terminated at Erie.

There's another one at Olney as well, I know the one at Erie was built with the intention that it would be another branch of the BSL, but I'm not sure about the one at Olney. The Olney upper level is currently used for turning Ridge trains. I don't think the one at Erie sees any traffic.

As I understand it, the flyover at Erie was built for a spur to either Chesnut Hill via Germantown Ave, or up the Boulevard. The Olney flyover was likely a provision to split the line into two northern branches, one up Ogontz Ave to Glenside, and the other up Old York Road, how far i'm not sure