THE NORTH Downs tunnel on the Channel Tunnel Rail Link (CTRL) has finished five months ahead of schedule and more than £5M under budget.
Since breakthrough in the middle of the 3. 2km long, 13m wide, 10m high tunnel was achieved in June 2000, work has continued 24 hours a day, seven days a week to complete the excavation and primary lining phases.
Permanent secondary lining works continued five days and nights a week, using two purposemade steel formwork frames. Each frame was 12m long and filled with 220m 3of fibre reinforced concrete every day, completing a total of 120m a week.
Finishing works included walkways down both sides of the tunnel and a central derailment barrier. The tunnel is now ready for installation of ballast, rail and catenary power supply.
On completion of Section 1 of the CTRL, the tunnel will carry Eurostar trains at up to 300km/h, halving journey times from London to the Channel Tunnel.
The CTRL will also create the infrastructure for new high-speed services between central London and north and east Kent.
Section 1 between the Channel Tunnel and Fawkham Junction in north Kent is now more than 70% complete and is on schedule to begin operating in 2003.
Major civil engineering for Section 2, between Southfleet in north Kent and St Pancras Station in central London, began in July 2001. More than £900M worth of contracts have been awarded so far, of a total contract worth of £1. 4bn due to be let by Union Railways (North) this year.