The grey stuff inexpertly photographed by me from the platform at Royal Oak Tube Station is a big pile of London clay, excavated from somewhere under central London to create Crossrail, a new commuter train service operating east-west across London. By the time the new trains begin operating in 2018, 26 miles of new tunnel will have been built – it is Europe’s biggest construction project. This grey heap sits in what Crossrail calls the Royal Oak Portal, the first of five new tunnel portals to be constructed for Crossrail which will provide the western entrance and exit for trains to the underground sections of Crossrail.

I find the sight of the clay terribly poignant. 

For a start, boring tunnels up to 40 metres below the city which curl and twist  between – in the sweet poetry of the Crossrail website – “Tube network, sewers, utilities, and London’s hidden rivers ” seems astonishingly extravagant behaviour.

Each Tunnel Boring Machine (TBM) weighs 1,000 tonnes and is 150 metres long. They operate 24 hours a day, 7 days a week, and in one day each can create up to 100 metres of tunnel. Imagine these blunt-nosed worms, each carrying as many as 20 workers, slowly eating their way under London. Boring has never been done to this complexity before and we are innovating because we have to: London is the world’s first city, it’s population is rising, international money pours into residential and commercial property, every day up to 1 million people – including me – turns up to work. This £15bn construction project is the latest example of London’s stubborn resistance against the calamity of its popularity, the limits of its geography, the aspiration of us all.

This humble pile of clay is an emblem of this resistance.

But its substance is also significant: organic, grey, inert – as old as this island. For millenia this clay has remained undisturbed. Think of what it has seen and preserved and borne. Scratch the surface and the incumbent Londoner is a serious, quietly anxious fellow – world-weary, hard-worked, but keen to do right by you if he can. This is not an extrovert town, even today; most Londoners keep themselves to themselves. And this pile of clay sitting at the Royal Oak Portal is London’s grey flesh, the city’s modest platform suddenly cut away and exported out of the darkness and out into unforgiving July sunshine. In the void that is left behind will form instant and beautifully crafted tunnels, housing track and wiring and maintenance passageways in dry, manageable conditions. Unseen, this new network creeps forward below our feet. Clay into tunnels, damp earth into dry space, dead matter into the valuable infrastructure of a world city.

But we live in an era of insecurity, and already there is talk of the next project – a Crossrail2, connecting south-west and north-east London via new tunnels beneath central London. Britain is locked into what David Cameron likes to calls a “global race”, and to win it we must continue to attract the world’s money and her best people to London. The government measures the cost of this success less publicly: average London house prices are now over £450,000 – London’s global success is pricing the next generation of Londoners out of their own city, and their options are hampered by the failure of successive governments to build sufficient numbers of homes within commuting distance. The row about whether or not Heathrow should be expanded pitches the self interest of west London residents against the perceived interests of the national economy. My money’s on a new runway going ahead. Competing with China and Brazil smothers the human dimension out of political considerations. But democratic politics always comes back to human considerations. Can globalisation be made to bow to the needs of the individual? This question defines the era of insecurity.

After I took the photo of the clay I boarded a tube heading east on the Circle line to Moorgate and the Square Mile. This section of the Tube is the oldest underground railway in the world –  wooden carriages using gas-lighting first ran between Paddington and Farringdon in 1863. We stalled outside Great Portland Street in awkward heat and the driver explained we were waiting for a signal change. At Kings Cross four Cross Rail workers got on and sat opposite one another, sharing opinions on minutiae of the tunneling process. Hot, grimy faces. Hard-used hands at rest on their laps. Hard hats pushed back on their heads. Hard words for that bloody fellow, and this effing project manager. I sat watching them, trying to imagine my self into their workplace. (Did you know that the TBMs carry toilet and kitchen facilities?) And all the time we sat there, I thought, the face cutter heads on Ada and Phyllis* were turning at  3 RPM, the cut clay was being picked up by the screw conveyors and sent back for processing, a sealed concrete tunnel was taking shape around them.

The clay won’t be wasted. According to Crossrail’s excellent website, “three-quarters (of all excavated material) is being delivered by rail and ship to Wallasea Island in Essex to create a new nature reserve in partnership with the RSPB. All excavated material from the western tunnels will be transferred by freight train from Royal Oak Portal to Northfleet.”

Bless this project. It is not the stuff of utopia but it is something extraordinary. So much of what we experience on a daily basis is remarkable, it’s just we have forgotten to notice. Alive today, in the midst of chaos, each of us scrabbling for purchase, we have two options: to be blasé and blind to wonders and horrors alike, or to celebrate that human progress has never been more complicated or more possible.

* The TBMs boring the western tunnels are named Ada and Phllis. Ada Lovelace was one of the earliest computer scientists. She worked with Charles Babbage on his ‘analytical engine’, and is regarded as having written the first computer program. Phyllis Pearsall single-handedly created the London A-Z. A portrait painter, she got lost on the way to a party in 1935 and decided the maps were inadequate. She walked 23,000 streets, and a total of 3,000 miles to compile the map, delivering the first 250 copies in a wheelbarrow.  www.crossrail.co.uk