October saw contractors removing the final plug of chalk from the Channel Tunnel Rail Link (CTRL) tunnel beneath the A2 at Pepper Hill, Gravesend in north Kent. This marked completion of excavations on Section 2 of CTRL.
The 564m Pepper Hill tunnel was built top down, with 45,000m3 of material, mainly chalk, excavated. Walls comprise 757 contiguous bored 1,200mm piles an average of 16m to 17m long, although some reach 30m depth.
The tunnel is part of a 3.5km stretch under CTRL Contract 342, worth £120M. A Hochtief/ Norwest Holst joint venture is carrying out the work on behalf of client Union Railways, which is being supervised by Rail Link Engineering.
'Construction of the tunnel was challenging as we had to maintain three lanes of traffic in both directions on the A2. This involved carrying out work in four phases and the construction of a temporary embankment, ' said jv project director Geoff Peagram.