Home Infrastructure A little bit of Jessica

A little bit of Jessica

Tunnel Boring Machines Jessica, Ada and Sophia delivered an unprecedented month of burrowing progress in January. Says Andrew Wolstenholme OBE, ‘The tunnelling teams deserve tremendous credit for their safe and efficient progress in constructing this major new railway under London.

‘The end is now in sight for Crossrail tunnelling with over 70 per cent of the new rail tunnels now constructed. The next major element of the Crossrail programme will now begin with the fit- out of our tunnels and stations.’

Crossrail’s western tunnels are now structurally complete with tunnelling machine Ada reaching the end of her journey at Farringdon on 24th January.

Ada set out from Royal Oak near Paddington in August 2012.

Over in southeast London, TBM Sophia has completed Crossrail’s first tunnel beneath the Thames, arriving at the North Woolwich Portal on 29th January, having started south of the river in Plumstead last August.

TBM Jessica has also completed her tunnelling journey from Pudding Mill Lane and broke through into one of Europe’s largest mined caverns beneath Stepney Green on 3rd February.

In addition, tunnelling machine Elizabeth made a spectacular entrance into the new Crossrail station at Whitechapel on 20th January on her journey from Limmo Peninsula to Farringdon. Her sister machine Victoria also broke through into Stepney Green on 30th January.

Civil construction

Crossrail has also finished civil construction of the first of two new Bond Street station ticket halls. The western ticket hall on Davies Street is five storeys underground. Engineers are now building a passenger tunnel to connect the Crossrail ticket hall with the existing underground station.

The 150 metre long, 1,000 tonne machines create 6.2m diameter tunnels by installing precast concrete segments in rings to line the tunnel. They are pushed forward by hydraulic rams and positioned using lasers and Global Positioning Systems.

Ada’s 6.9 kilometre journey has been particularly challenging for engineers, successfully navigating a complex web of Tube lines, building foundation piles and infrastructure up to 30 metres beneath central London. This included passing less than a metre above the operational Northern line at Tottenham Court Road.

More than 72,000 pre-cast concrete segments have been used to line the western tunnels and about two million tonnes of earth has been excavated, destined for a new RSPB nature reserve at Wallasea Island, Essex.

Olympic champion

Tunnel Boring Machine Jessica is named after Olympic champion Jessica Ennis-Hill CBE. TBM Ada is named after Ada Lovelace, who was one of the first computer programmers while Phyllis is named after Phyllis Pearsall who created the London A-Z.

Elizabeth and Victoria are named after Queen Elizabeth II and Queen Victoria. Sophia is named after the wife of Marc Isambard Brunel who built the first tunnel under the Thames. An eighth TBM, Ellie, named after Paralympic gold medalist Ellie Simmonds OBE will be launched soon.

TBM Jessica will be taken to Limmo Peninsula for reassembly where she will construct the new Crossrail tunnels between Limmo and Victoria Dock Portal. The drama continues as the project moves from tunnelling to fit-out.

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