More jigsaw pieces are about to be put in place in the £16 billion Crossrail project with another two giant tunnelling machines getting ready to be shipped to east London.

One will be used to complete the link under the Thames between Plumstead and North Woolwich on Crossrail’s Canary Wharf-Abbey Wood branch, the other to drill twin tunnels on the Shenfield branch between Stratford and Stepney Green, both branches joining at Whitechapel.

These are the sixth and seventh drilling machines to be brought in, both of which have now completed tests at the Herrenknecht factory in Germany before being ‘boxed up’ and made ready to be transported to Rotterdam and put on a ferry to Tilbury.

Machine 6, nicknamed ‘Mary’, will be reassembled in Plumstead ready to drive its way under the riverbed to North Woolwich, following a parallel path of its ‘sister’ machine ‘Sophia’ which began drilling at the beginning of January.

Machine 7 is to drive a tunnel from Stratford’s Pudding Mill Lane site towards Stepney Green and Whitechapel. This is an Earth Pressure drill specially designed for clay soil found in east London.

The machine components arrive at Crossrail’s sites in the next month, to be reassembled ready to start work.

Crossrail’s Andy Mitchell said: “Once we’ve unpacked and reassembled machines 6 and 7, they’ll begin drilling under the streets of east London. We’ve already dug more than three miles of tunnels.”

Drilling the section between Canning Town and Whitechapel is already well under way with machines 4 and 5 following one-another which are expected to arrive under Canary Wharf later this year, before heading on to Whitechapel and the City.

Crossrail’s final tunnel boring kit, Machine 8, completes factory testing this summer.