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Channel Tunnel Rail Link, Contract 250: Ripple Lane to Barrington Road Tunnels

The Channel Tunnel Rail Link relates to a railway high-speed connection from the north portal of the Channel Tunnel near Folkestone to St. Pancras Station in the centre of London, which ensures that Great Britain is joined up to the European high-speed network. The project included the building of a 109 km long, twin-track new route, which is primarily intended for passenger traffic. Contract 250 represents the part-section of this link sited in Greater London. This contract section embraced the building of two 5.3 km long single-track tunnel tubes with 7.1 5 m internal diameter, 7 cross-passages between the tubes, ventilation structures and an access ramp for the Ripple Lane Portal. As the railway route is devised for a speed of 300 km/h, the longitudinal gradient for the first 200 m amounts to 4.6 ‰ and 3.6 ‰ for the remainder of the route. The tunnels were driven with a minimum radius of approx. 2,500 m. The minimum overburden of 7 m is slightly less than the diameter of the tunnel. The two tunnel tubes were driven simultaneously from a trough structure with two EPB machines with 8.15 m external diameter. The driving Installation was altogether 110 m long and consisted of an approx. 10 m long shield and 10 trailers. At the "Barrington Road Ventilation Shaft" target point the skin of one shield was left in the ground, the other was retrieved from the excavation pit for the ventilation shaft. Various geological formations had to be penetrated during the drive: Terrace/flood plain deposits, London Clay, Woolwich and Reading beds and Thanet Sands. In the process the groundwater level was on average 21 to 27 m above the tunnel floor. The tunnel lining constitutes steel fibre reinforced segment rings, which are made up of 9 concrete elements and a keystone. The elements are 1.50 m wide and 0.35 m thick. Tunnelling operations commenced in February 2001 and were concluded in spring 2004. The project was handed over to the client as scheduled in September 2004.


  • Country: United Kingdom
  • Region: London
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Union Railways (North) Ltd.
  • Consulting Engineer: RLE Rail Link Engineering
  • Contractor: JV: Edmund Nuttall Ltd., UK/Wayss & Freytag Ingenieurbau AG, Germany/Kier Construction Ltd., UK
  • Main construction method: Trenchless
  • Type of excavation: Shield machine (SM)
  • No. of tubes: 2
  • Tunnel total length: 10,600 m
  • Cross-section: 56.9 m² (bored diameter)
  • Contract Volume: 217 mill. Euro
  • Construction start/end: February 2001 till September 2004
  • Opening: November 2007