THIS is the first of two 1,000 tonne tunnelling beasts that will be carving paths under the Thames for Crossrail’s link between Abbey Wood and central London.

Colossal tunnel boring machine (TBM) ‘Sophia’ is 110 metres long and currently in Plumstead ahead of her 2.6km journey under the river which is expected to begin in January next year.

The tunnels will dive 2.3km beneath the Thames and form part of the £16 billion Crossrail construction - one of the largest infrastructure projects ever taken on in UK - with services timetabled to be running in 2018.

Sophia has a rotating cutter head of 7.1 metres diameter which will churn up the chalk soil under the riverbed for 24 hours a day and will be manned by a team of around 20.

Another gigantic Slurry TBM, Mary, will help bore out a second link between Plumstead and North Woolwich - dubbed Drive H - in the middle of next year.

Project manager for the Thames tunnel contract Gus Scott said: "This is a landmark step. Crossrail has worked for six years to get to this moment to start tunnelling on Drive H.

"We are the only part of Crossrail going under the Thames and are really excited to be getting it underway."

Twin giants Mary and Sophia are two of eight machines used by Crossrail to clear large volumes of ground beneath London and erect concrete tunnel lining.

To track their progress, visit

Tunnel naming tradition

Sophia was named after the wife of Marc Isambard Brunel who built the first tunnel under the Thames; Mary was the wife of railway engineer Isambard Kingdom Brunel.