Setting out the Channel Tunnel Rail Link

The £5·2 billion Channel Tunnel Rail Link is the largest single civil engineering project currently under construction in the UK. Due for completion by end 2006, it will cut train journeys to Europe by 35 minutes and make it possible to get from London to Paris in just 140 minutes. On the first 74 km section, which is now 60% complete, all setting out and as-built surveys are being undertaken by way of an innovative shared network of state-of the-art global positioning system (GPS) base stations. Using compatible GPS rover units, contractors are able to transfer project design information directly to the field to an accuracy of ±25 mm horizontally and ±20 mm vertically. This paper describes the thinking behind the approach, how it has worked in practice and in particular how it has helped to foster a partnering environment.