Running the "Treel Tunnel". On a late fall afternoon, the Northern Central Railway's Locomotive "York 17" charges south through the dense "tree tunnel", about 3/4 of a mile north of Gladfelter Station, in the town of Seven Valleys, PA, heading back to her home in New Freedom, some 10 miles to the south. On the left side of the tracks as you view them, is the York County Heritage Rail Trail, which parallels the route of the Northern Central Railway along all of its current usable trackage. This rail trail is very popular with both hikers and bikers and is definitely something that rail enthusiasts need to consider when photographing this line.