Camden New Journal - ST PANCRAS INTERNATIONAL MAGAZINE Published: November 2007
Going underground
BETWEEN burrowing under the Thames and trying not to wake the neighbours, bringing high-speed trains into the heart of London is no mean feat.
Twenty kilometres of underground tunnels link the route of TGV trains between Dagenham and St Pancras International and for the last three and a half years a dedicated team of engineers has been working flat out, installing concrete-bedded railway track and high-speed overhead lines.
Led by Alstom – the power generation and rail transport company behind the TGV trains – the €178 million project comprised two successive tunnels, the first under the Thames, the second under the City of London.
Inside the tunnel, 30,000 cubic metres of concrete were produced to bed the line at a rate of 350 metres per day. A further 350 metres of tunnel were concreted every night.
Due to the thousands of people living above, it was essential to minimise the noise and vibrations caused by the super-powerful trains.
To achieve this, an innovative system was used. Engineers fitted reinforced twin-block concrete sleepers with 18-mm-thick “elastomers” – a shock-absorbing base-plate – inside.
Thanks to these sleepers the entire rail is cushioned, limiting ground vibration from passing trains and ensuring quiet nights for those above.