Crossrail is a new rail line which will open in 2018 and run from Reading and Heathrow in the west, through 21 km of new twin-bore tunnels and seven new underground stations under central London to Shenfield and Abbey Wood in the east. In 2007 Canary Wharf Group agreed to build the new station at Canary Wharf on the South East leg of the Crossrail route for a fixed price of £500m and contribute 30% of the cost
The Station is being constructed to shell & core specification under a design & construct contract with Canary Wharf taking all the design, cost and programme risk.
The box structure which forms the enclosure of the station has been built in the 10m deep North Dock of West India Quay and extends some 18m below the bed of the dock. It is also adjacent to five major office buildings including the HSBC tower which is 45 storeys high.
The original temporary works proposals were challenged by CWCL using our extensive knowledge of constructing buildings and infrastructure in London Docklands over the past 24 years. As well as a more efficient station design, this resulted in far less intrusive works in the docks and considerably reduced environmental impacts. The station box is still 256m long making it longer than the height of One Canada Square which, until recently, was the United Kingdom’s tallest office building.
To enable construction of the station box, 296 tubular steel piles measuring 18.5 metres long and 1.2 metres diameter have been hydraulically driven into the dock floor using Giken Piling machines, which are virtually silent and produce no vibrations that could disturb neighbours.
Construction commenced with the relocation of dock silt in January 2009 followed by the formal commencement of the piling for the coffer dam in May 2009. A top down method of construction was adopted so that the potential for ground movements was minimised and the plan area of the worksite was kept clear for the piling works and subsequent activities.
KEY POINTS OF INTEREST
|• Giken test piles (to prove programme (i.e. 3 piles per day) February 2008.|
|• Giken rigs ordered from Japan in October 2008, to secure supply of 1200 mm diameter rigs.|
|• Revised design saved 45m of station length or 22% by volume.|
|• Use of a single skin cofferdam reduced the footprint of temporary works on the docks by approx 70%.|
|• 71 tension piles installed from the dock bed to prevent long term buoyancy of the station box.|
|• 98,000,000 litres of water (equivalent of 40 Olympic swimming pools) removed from within the cofferdam to reveal the dock bed for the piling mat and the ceiling of the station Ticket Hall.|
|• Use of barges to remove spoil saved approximately 29,000 truck movements.|
|• The station box ready in March 2012, five months ahead of schedule, to receive the Tunnel Boring Machines which were launched from Limmo Peninsula (1.7km east ) in late 2012.|
|• CWCL are building the station to Shell & Core stage with Crossrail responsible for installing the Railway and Linewide systems between mid 2015 and mid 2018.|
|• Fit-out activities by CWCL commenced in April 2012 with blockwork and services, whilst the above ground elements were completed.|
|• Platforms formed of 580 pre-cast units, with an average weight of 3.5tonnes.|
|• Feature roof over 300m long made up of 1,414 glulam (timber glued, laminated) beams and 780 ETFE cushions.|