In August of 2014 I traveled up to the eastern terminus of the Pennsylvania Turnpike and explored Sideling Hill Tunnel and the Turnpike mainline east of the tunnel. I immediately noticed that someone has been painting the exposed tunnel surfaces to remove the graffiti and defeat rust, and that several new-looking laminated signs were posted warning people to stay out of the ventilation rooms.
The Pike 2 Bike website is currently AWOL and my Googling didn't turn up any obvious info on the planned sale of the abandoned Turnpike to Bedford County, so I was curious to know which entity is theoretically responsible for the Turnpike and the tunnels and if the old plans to rebuild one of the travel lanes and light the tunnels have been dropped.
This guy has the same question: http://www.abandonedturnpike.com/home.htm
According to Fulton County's GIS mapper (http://gis.co.fulton.pa.us/) (throwaway account gis153/gis080709), the ROW in Fulton County is split between the Turnpike Commission and the Department of Forests and Waters (now Conservation and Natural Resources).
Stay out of the ventilation rooms, unless you want to climb the one working staircase at the west end of the east tunnel. Then you can explore the ventilation rooms.