Important step towards the LHC

It is coming up to 16:00 on 15 May and a group of some 50 people, fully kitted out in boots, helmets, and masks is intently watching a point on the wall in front of them. They are down in the LEP/LHC tunnel waiting for civil engineers to excavate the last few centimetres separating them from the TI2 transfer tunnel. The noise of machines begins, and just five minutes later the wall comes tumbling down. The excavator breaks through right on target, bringing a two-year project to a happy conclusion. Later, the survey team published the outstanding result that the tunnel junction was made within
6 millimetres of target.
TI2 measures 2648 metres in length and three metres in diameter. Around 32,000 cubic metres of rock have been excavated to make it, so the 15 May breakthrough was a sign for a little celebration. The 50 waiting people stepped through to the tunnel to meet up with others and raise a glass. Among the subterranean celebrators were Director-General, Luciano Maiani, LHC Project Director, Lyn Evans, and some of those responsible for the civil engineering - Jean-Luc Baldy, Robert Fielder, Johanna Stephanie Rammer-Wutte, and Tim Watson.

Work for TI2 began in October 1998 when an 18 metre wide, 47 metre deep oval access shaft was sunk in the West Area. Construction of the tunnel then proceeded in two directions - from July 1999 towards the SPS and from May 2000 towards LEP. Since the SPS is in a shallower tunnel than LEP, TI2 is not flat. It is 40 metres deep on the SPS and 50 metres deep on the LEP/LHC side. Moreover, there is a point at which the path of the tunnel crosses a watertable underneath the river Le Lion, so the tunnel dips to keep out of the underground water's way.
TI2 will have an important role to play even before the LHC starts up in 2006, since it is along this tunnel that the new accelerator's over 1300 main dipole magnets will be transported into the ring. Whilst that is going on, the anticlockwise transfer tunnel, TI8, will be equipped with the transfer line that will steer protons from the SPS into the LHC. TI8 excavation is scheduled for completion in early September this year. When the last dipole is in place and anticlockwise-moving protons are making their first turns in the new accelerator, a clockwise transfer line will be installed in TI2 ready for the great LHC adventure to begin.
Two companies from Britain and one from France have worked together in a joint venture to construct TI2 - Taylor Woodrow, Amec, and Spie Batignolles. Some 50 people have been involved in the works.