Channel Tunnel Rail Link section 2: north Thames marshes.

The 12 km north Thames stretch of section 2 of the Channel Tunnel Rail Link—now known as High Speed 1—involved constructing a high-speed railway formation across marshlands next to the Thames, alongside operating railways and crossing major roads. This paper describes the design and construction of the 12 km section which links the Thames tunnel to the London tunnels. The work included the push-launch of a 1 km long viaduct at Thurrock, which threads its way under and over the M25 bridge and tunnel crossings of the Thames respectively. [ABSTRACT FROM AUTHOR]