BANK EXTENSION

BANK    BECKTON    LEWISHAM

Into the City....
The initial Railway had been constructed under a design and build contract with GEC-Mowlem Railway Group carrying out all the tasks neccessary to provide a complete railway. This formula was repeated with the extension further into the City, to Bank Station. On17th July 1987 - before the original railway had even opened for traffic - two contracts were awarded; to Ednumd Nuttall Ltd, for the westward extension in tunnel to Bank, including construction of the DLR station at Bank; and to GEC-Mowlem Railway Group, for the upgrading of the existing system, extension of electrical systems through the E.Nuttall contract works, and provision of new vehicles. A single 100-tonne tunnelling machine was constructed in Britain, to a German design, to bore the 1.6km extension westwards from Royal Mint Street. Following a Start of Tunnelling ceremony on 14th March 1988 the westbound tunnel was bored first, breaking through into the new King William Street station site on 7th December 1988. The machine was then withdrawn from the westbound tunnel and put to work digging the second one, to become the eastbound tunnel. This bore was completed in February 1990. Tunnelling through the London clay was achieved at an average at an average rate of nearly 100 metres per week.
The circular cross section tunnels were bored by the 5.39 metre diameter tunnelling machine, then lined with precast concrete segmental linings: the internal tunnel diameter permits the provision of a walkway on one side, which allows not only access for maintenance but evacuation of passengers, including mobility-impaired passengers, in an emergency.	The Eastbound Platform at Bank.
A DLR train at Bank in March 1991, 4 months before services commenced		In order to bore the larger seven-metre station tunnels the existing tunnelling machine was plugged into the centre of a larger 7.75 metre station tunnel machine, retaining the smaller machine's facilities to power the larger machine, retaining the smaller machine's facilities to power the larger machine. As much as 2000,000 tonnes of clay was excavated and taken to various sites east of London including the site of the former Beckton Gasworks. Generally, the tunnels were bored at depths greater than 30 metres below ground with the Bank station at a depth up to 42 metres below ground.
Beneath the Mansion House, a Grade 1 listed building, it was necessary to dig a step-plate junction between the two running lines. Special tie bars were used to secure Mansion House following the necessary approvals in July 1990. The step-plate junction was completed in March 1991 and although there were some signs of movement in one corner of the building, it suffered no damage. As well as the main work, substaintial effort was needed to rebuild and integrate the London Underground Monument station to provide links to the new DLR facilities. In particular a new concrete slab ws cast above the existing station to support a new building to be constructed over the ticket hall. This required 30 metres deep hand-dug shafts to accommodate the necessary vertical piles. The first DLR train into Bank was P86 vehicle 03 hauled by a diesel locomotive and used for measurement purposes on 11th July 1990; slightly over one year later, public opening using the westbound tunnel was achieved on 29th July 1991 with the second eastbound tunnel following on 29th November 1991.

BANK    BECKTON    LEWISHAM