CTRL will be Europe's biggest civil engineering project since the Channel Tunnel was completed in 1994 and will involve about six times the volume of tunnel excavation completed in the Jubilee Line Extension. Large diameter tunnels through which trains will speed beneath London from north of St Pancras to emerge at Dagenham, Essex will start in sound clay but finish in difficult water bearing gravels of the Thames estuary.
Track Link, a joint venture between Mowlem, German contractor Philipp Holzmann and Belgium's Besix is preferred contractor for £65M of tunnelling work in London under Contract 210.
The contract covers a 1.6km stretch of twin CTRL tunnels from the railway lands north of King's Cross to Islington, plus two 0.6km Thameslink tunnels linking between the East Coast Mainline and St Pancras.
Holzmann's involvement in the project comes on the back of its involvement in the Connect DBFO roads consortium and a failed bid for the CTRL franchise. It has also carried out major tunnel projects in Germany and the Netherlands.
Mowlem has much past, but little recent, tunnelling expertise although it is working with Japanese tunneller Mitsui on the construction of the Docklands Light Railway Lewisham extension.
Belgian contractor Besix has worked on the Belgian high speed rail link between Brussels and the French border as well as building siphon tunnels under the Suez Canal.
The two 5.4km CTRL tunnels between Barking and Dagenham are to be constructed by a joint venture between Edmund Nuttall, Germany's Wayss & Freytag and Kier Construction under contract 250.
Tunnellers will use two 7.15m diameter earth pressure balance machines to build the bored sections of the tunnels.
Work also includes 300m of retaining walls and 197m of twin cut and cover tunnels at the approaches to the bored section.
Dutch contractor HBG dominates the consortium as it controls Nuttall and Wayss & Freytag. All three consortium members have extensive recent tunnelling experience.
Wayss & Freytag worked on the Jubilee Line Extension with Sir Robert McAlpine and Nuttall built the Docklands Light Railway's underground extension into Bank station. Kier worked on tunnels for the massive Lesotho Highlands water project in Southern Africa.