Tag Archives: TBL

Like every other journalist in London, I wrote an article about the Crossrail project. It appeared in Eurostar’s Metropolitan magazine in May and is reprinted here.

In a cavern 35 metres underneath Stepney City Farm, London is getting smaller. Not literally of course, that would be terrifying. No, this gigantic space under east London has been excavated for Crossrail, the 42-km high-speed tunnel being built beneath London. When it opens in 2018, Crossrail will carry 200 million passengers every year from east to west (or west to east), cutting the city down to a more manageable size as journey times are greatly reduced. When Mayor Boris Johnson entered a similar Crossrail site in Canary Wharf he gushed it was “like a Neanderthal stumbling into the gloom of Lascaux… akin to a gigantic subterranean cathedral several times the size of Chartres.” In truth, the Stepney cavern is more like a big, bare quarry, shaft open to the sky, lined with concrete and exuding a faint smell of wet earth.

“If Crossrail is a Y, we are standing where it splits,” explains Will Jobling, Crossrail construction manager, pointing at a map that shows Crossrail travelling across London to Stepney, where it divides with one leg heading north-east and the other crossing the Thames to Abbey Wood in the south-east. “Two of the tunnel boring machines (TBM), Victoria and Elizabeth, have passed through here and you can just see the back of one on its way to Farringdon. They should get there by February 2015.”

There are eight TBMs working on Crossrail, giant moles that slowly grind through London clay at the rate of around 150 metres a week. Weighing 1000 tonnes and with rotating, earth-scraping heads, these monsters run 24-hours a day and are like mobile factories, removing dirt and sealing the tunnel with concrete as they move. They even have canteens and toilets as well as a rescue chamber in which workers can take refuge in case of an accident. Around 4.5 million tonnes of earth (which Jobling says has the consistency of “elephant dung”) will be transported by barge to the Thames estuary to create a man-made nature reserve. One machine, Jessica (named after Olympic athlete Jessica Ennis), is being removed at Stepney. It’s taken apart underground, lifted out the shaft then transported to Canning Town, where it will be welded back together and lowered into the ground to continue tunnelling. Parts of Jessica lie strewn across the Stepney site, battleworn, clay-scarred and weary but with more work still to do. They look like ancient artefacts salvaged from the seabed.

The TBMs cost £10million apiece and are fitted with lasers that help engineers plot a course around and under London’s subterranean obstacles – sewers, foundations, plague pits, buried rivers and other tube lines. “At Tottenham Court Road, we come within 80cm of the Northern Line,” says Jobling. “We look at every obstruction we could possibly find. Sometimes we have to back-engineer, look at how high a building is and then work out how deep the piles will go.”

Despite this, the basic principles haven’t changed since Marc Isambard Brunel invented the tunnel shield to dig the Thames Tunnel from Rotherhithe to Wapping between 1825 and 1843. Some methods go back even further. “At Canary Wharf we hit a bunch of old piles that we had to cut through by hand using old mining techniques,” says Jobling. “The older guys loved it.” He’s interrupted as a loco, a miniature train used by workers to travel through completed tunnels, scoots noisily past. It’s like an old mining cart, only it runs on diesel and is deafening. As the TBMs approach Farringdon, workers will have an 8km underground commute on the loco to work every morning. When the screeches have stopped echoing off the cavern walls, Jobling explains how a ceremony was held at the start of operations as priests blessed 38 statues of St Barbara, the patron saint of miners, and placed them at tunnel mouths. “Tunnellers can be a superstitious lot,” he notes.

Crossrail will be followed by similar huge projects – the Northern Line extension to Battersea, a gigantic sewer called the Thames Tideway, and possibly a north-south Crossrail Two – and to ensure London retains its tunnelling knowhow, Crossrail opened the Tunnelling And Underground Construction Academy (TUCA) in Ilford in 2011. In a building designed to look like a TBM entering the ground, workers are trained in a specially developed environment that includes a replica of Crossrail tunnel. “We get them used to working in an enclosed space,” says Georgina Bigam, Skills And Training Manager. “Everything can be installed and dismantled. We also do a safety course where they fill the tunnel with smoke, turn off the lights and simulate explosions by chucking firecrackers around for half-an-hour. They have to find their way out.” She pauses. “I usually make the journalists do it,” she says, and giggles.

TUCA trains hundreds of people to work beneath London’s soil. The canteen – complete with mural of UK tunnelling landmarks – is filled with eating, gossiping men (and one woman) of all ethnicities, from Cockney grease monkeys to a middle-aged Sikh with hard hat screwed on top of his turban. Many gain knowledge that is valued all over the world. As Valerie Todd, TUCA’s Talent and Resources Director, explains. “There’s tunnelling happening right across the world as cities everywhere are facing similar pressures, looking to find ways to move a lot of people around very quickly when the surface area is used up.” But Crossrail is the current focus, a £15-billion project that is Europe’s largest infrastructure project and which Boris Johnson has likened to conquering Everest. Onward push the TBMs, while the city sleeps and workmen come and go. Saint Barbara would be proud