Crossrail engineers have begun to ‘open up’ the Connaught Tunnel to carry out essential works ahead of the arrival of Crossrail trains in 2018.

A hole has been drilled in the crown of the Victorian tunnel to allow above-ground access from the drained Royal Victoria Dock.

The hole will be widened to approximately 20 metres long and 10 metres wide so that material can be easily removed from the tunnel as work continues on its central section.

Before drilling could be carried out, 13 million litres of water has had to be drained from the docks.

Sections of the Connaught Tunnel – the only tunnel to be re-used for Crossrail – are in a poor condition and parts of it were narrowed during the 1930s so that the dock could be deepened to accommodate larger ships.

The tunnel was built in 1878 and has not been in passenger use since December 2006.

Linda Miller, Connaught Tunnel project manager, said: “The Connaught Tunnel is testament to the engineering skill of the Victorians, but after 135 years there’s a lot of work that needs to be done to get it ready for Crossrail.

“Now we’ve opened the top of the tunnel we’ll start the engineering equivalent of open heart surgery – widening and deepening the structure so that it can accommodate up to 12 trains an hour in each direction.”