June 24, 2013 4:23 pm

Crossrail stacks up some big numbers


As Europe’s biggest civil engineering project by value, Crossrail generates some eye-popping statistics along with the 4.5m tonnes of spoil excavated.

When it opens in 2018 it will be the single biggest addition to the southeast rail network in 50 years, lifting rail capacity in the capital by 10 per cent at a stroke. The line will drastically shrink journey times across the city, bringing passengers from Paddington to the City of London in nine minutes and Canary Wharf in 16. Heathrow to Canary Wharf will take 39 minutes.

London was transformed at the hands of engineers in the 19th century, when an army of navvies used pickaxes and brute force to create the railways, canals, roads, sewers and tunnels that fuelled the growth of the Victorian capital.

Their modern equivalents include the delicately named Ada, Phyllis and Sophia, three of the eight tunnel boring machines chewing through London’s clay, sand and silt at a rate of 100m a week.

On the day the FT visited the site of the line’s Canary Wharf station, two of these formidable machines were temporarily out in the open. Their scale is immense: each weighs 1,000 tonnes, has a diameter of 7.1m and is as long as 14 London buses. But they use laser guidance to pick a path under central London to millimetre-fine accuracy.

Engineers have had to take steps to protect offices from noise and vibration as well as the dangers of digging near old, brittle parts of London’s sewer network.

“It’s a huge engineering challenge to protect the assets around us,” said Terry Morgan, chairman of Crossrail. “St Paul’s Cathedral, for instance, has no foundations. But the Gherkin has very deep foundations, to precisely the depth at which we want to tunnel.”

The ticket offices and platforms at Canary Wharf are housed in a cathedral-like concrete box, 250m long and 40m wide, that engineers have constructed beside the wharf’s office towers. Engineers pioneered new piling techniques at the site and pumped nearly 100m litres of water from the dock that surrounds the box.

Crossrail has spent nearly £800m on compulsory property purchases, sometimes where residents have been rattled by the noise of construction. “However well we do this job, it is intrusive,” said Mr Morgan. “Sometimes it’s better to say to people: ‘We’ll buy your property off you, and you can relocate’.”

Fortunately for the taxpayer, London’s buoyant property market has dispelled any worries over resale.

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