Completely new tunnel, but it will be connected to LHC, as they will use LHC to pre accelerate the particles.

Almost all accelerators built at CERN are still active and are a chain of pre-accelerator for LHC now:

https://en.wikipedia.org/wiki/Large_Hadron_Collider#/media/F...

wow. Amazing map. Just imagine Half Life map with it... :)