Lep/LHC share 
the same tunnel This is one proposed design for the LHC tunnel at CERN. Though the LHC will share the tunnel with the older LEP, they are at present completely separate. One day physicists may collide electrons from the LEP with protons from the LHC.

One of the four LEP monorail trains suspended from the ceiling of the 27 km long LEP tunnel. Three such trains circulate in the tunnel transporting goods and people.

Computer graphics of LHC positioned in the existing LEP tunnel.