In pictures: Breakthrough at London’s Crossrail project

Crossrail workers wait as a tunneling machine breaks through into the Whitechapel station on April 4, 2014 in London. The breakthrough marked completion of 75 per cent of the tunnelling work, which will be finished in 2018. Dan Kitwood / Getty Images

A worker walks through the Connaught tunnels section of the Crossrail project. Andrew Winning / Reuters

Workers pour concrete to form a strengthening slab inside the Connaught Tunnel, an old Victorian tunnel which is being brought back into use for the Crossrail project. Adrian Dennis / AFP

Visitors walk past excavating machinery inside the Connaught Tunnel, which is being brought back into use for the Crossrail project. Adrian Dennis / AFP

Crossrail supervisors make checks on the tunnel after Victoria, a tunnel boring machine broke through at Whitechapel underground station. More than 19 miles of tunnelling have now been completed. Plunkett / Reuters

Workers lay concrete in the Connaught Tunnel section of the Crossrail construction project. Crossrail is Europe’s largest civil engineering project and is due for completion in 2018. Andrew Winning / Reuters

Workers wait in a tunnel after a Crossrail tunelling machine broke through into the Whitechapel station. Dan Kitwood / Getty Images

A worker walks out of the Connaught Tunnel section of the Crossrail project. Work is taking place to create a new platform and passenger tunnels for a new Crossrail station. Andrew Winning / Reuters

A worker drills into the original brickwork inside the Connaught Tunnel, an old Victorian tunnel which is being brought back into use for the Crossrail project. Adrian Dennis / AFP

Workers in the Connaught Tunnel section of the Crossrail construction project. Crossrail is Europe’s largest civil engineering project and is due for completion in 2018. Andrew Winning / Reuters

A worker dismantles scaffolding in the Connaught Tunnel, which is being brought back into use for the Crossrail project. Andrew Winning / Reuters

Crossrail project supervisors look at the roof of an old Victorian tunnel, built in 1879 but has been derelict since 2006, which is being brought back into use for the Crossrail project. Adrian Dennis / AFP

A worker walks at the Connaught Tunnel section of the Crossrail project. Work is taking place to create a new platform and passenger tunnels for a new Crossrail station. Adrian Dennis / AFP

The £15 billion Crossrail project reached another landmark when a tunnel boring machine named Victoria broke through into Whitechapel station in east London.