Up close and personal with Crossrail's monster tunnelling machines

With Europe’s largest megaproject taking shape deep beneath London’s streets, Stuff descends into the bowels of the earth to find out more

Seven floors below the surface of London, a five-minute climb down aluminium steps that lead into the huge, concrete-lined chambers that will make up Farringdon Crossrail station, this mighty project doesn’t look like a Digital Railway. It looks like an enormous hole in the ground.

Which, of course, it is, but Crossrail isn’t just a physical system. In and around these immense tunnels – the platforms are so big that some station entrances will be more than a quarter of a mile apart – an invisible structure is evolving. All around us there are stations, platforms, pilings and escalators, built as digital models, visible in augmented reality, waiting to be realised in concrete and steel. Looking through the augmented reality app built specially for the project, you can see the huge components that will be clicked into place.

This isn’t just a fun app for checking out what will be here in 2018, though. In fact, the app is unlikely to make it into public use – as the site manager explains, publishing the layout of every cable and substructure of London’s new transport mainline would be a spectacularly unpopular move with the police and security services. But for the people building Crossrail, and for the people who will run it for the next century – these things are built with a minimum 120-year lifespan in mind – the physical railway and the digital railway are inseparable.

Without a computerised reflection of what’s being built, Europe’s largest engineering project would be impossible to co-ordinate; there are 10,000 people currently working on Crossrail’s 40 construction sites. And as the real-life tunnels and walls and supports go into place, the digital model grows and adjusts: engineers watch the components move into place through the AR app, which registers when they meet with the digital model and updates it. Measuring lasers, movement sensors and even iBeacons keep a digital eye on the real-world environment and adapt the model, not just for the engineers working on Crossrail now but also for their successors, decades from now, who will have an ever-changing digital copy to refer to.

This article first appeared in the April 2015 issue of Stuff, the world's best-selling gadget magazine. We'll print loads more fascinating features, news and reviews and bring them right to your house, if you subscribe here.