The UK’s largest construction project is gaining momentum as more station upgrade work is awarded and contract appointments for 18km of twin bore tunnels are awaited. Five contractor consortia are in the running and expressions of interest have also been invited for a third tunnelling contract consisting of a 2.6km section crossing the River Thames.
A total of 42km of TBM bores are expected for the massive GBP 15.9bn (USD 24.5bn) railway, which will run east west across London with 118km of new railway lines starting at Shenfield and Abbey Wood and running through central London to Maidenhead and Heathrow in the west. It will consist of four main lines: A 68km section from Maidenhead to Stepney Green Junction; a 30.5km line from Stepney Green Junction to Shenfield; a 13.0km length from Stepney Green Junction to Abbey Wood and a 7km spur from Heathrow Junction to Heathrow Airport .
Station upgrades
In terms of stations a total of 28 station upgrades are required for the Crossrail scheme mainly involving London Underground’s major tube stations. Eleven of these are full reconstruction projects. A total of eight new stations will also be built for Crossrail including the first Crossrail station to get underway located at Canary Wharf.
Construction of the new 256m long, 30m wide station box began in May 2009 and set a tricky challenge for Canary Wharf Contractors (CWC), a subsidiary of developer Canary Wharf Group, which is investing GBP 150M (USD 232M) of the total GBP 500M (USD 772M) required for the scheme. The first activity for the GBP 500M project was to build a cofferdam to hold back the dock water and create construction space but due to the built up nature of the site, noise reduction was a key requirement. The team via subcontractor Laing O’Rourke subsidiary Expanded Piling opted to use Japan’s Giken piling method that claims to be silent thanks to the use of hydraulic pressure to drive the 18m long tubular steel piles. The rig crawls along the top of the previously installed piles and uses the reactive force of the ground to drive the next pile. A crawler crane sitting on a floating support barge then feeds the rig with the next steel tube. A C-shaped clutch detail is used to hold the tube, which is then grouted up to form a water tight seal.
A second traditional piling rig follows the Giken to place the reinforced concrete piles. The first task is to pump out the water and then it excavates down to 33m. This hole is then filled with the concrete and additional support is provided via anchor piles sitting just to the north, connected with steel cables. A total of 310 piles were driven and once the cofferdam was completed the team began dewatering the dock in February removing 98 million litres of water through two 6in diameter pipes. Construction of the six storey station box is now underway for completion in 2015.
The next station to get underway was Tottenham Court Road. A new station is required to service the Crossrail trains but the work underway concerns expansion of the existing tube station. Taylor Woodrow Construction and Bam Nuttall were announced as the winning contractor teamin December 2009 and the scope of works includes construction of an enlarged ticket hall, new station entrances and additional access points to the Northern and Central line platforms to reduce congestion, along with additional escalators and five new lifts to provide step-free access. “The Tube station will be extensively redeveloped tomake the ticket hall around six times larger and the station will have twice the capacity than at present,” says Miles Ashley, head of London Underground station capacity programme. “By 2017, Tottenham Court Road will be one of the most important transport hubs in the West End as it will serve both London Underground and Crossrail.”
The new Crossrail station to be built at Tottenham Court Road is yet to be tendered. However some extensive tunnelling work has already been completed at the station with contractor Birse having diverted over 40 utilities since July 2007. All works at this station will be completed by 2016.
The next stations to progress will be Paddington, Victoria, Bond Street and Farringdon. At Paddington five contractors have been invited to bid for the scheme including Bam Nuttall, Bovis Lend Lease, Carillion Capital Projects Ltd, Laing O’Rourke, Morgan Est and Vinci Construction Grand Projets. A GBP 700M (USD 1.08bn) contract for the redevelopment of Victoria station was also awarded to Taylor Woodrow with Bam Nuttall in March 2010.
A GBP 300M (USD 463M) redevelopment of Bond Street Tube station was awarded to the Costain Laing O’Rourke joint venture last month. The contractor will increase the station’s capacity to enable it to serve over 225,000 passengers per day, from 155,000 today. Other requirements are a new ticket hall that provides step-free access to the Central and Jubilee Lines, new escalators and an alternative route to the Jubilee Line to ease congestion, as well as access to the new Crossrail station. “By 2017, Bond Street station will be served by both London Underground and Crossrail and will be a key gateway to the West End. This redevelopment is essential to ensure the station can accommodate the large increase in passengers that will use the station,” says Crossrail capital programme director David Waboso.
More station contracts for Whitechapel, Liverpool Street, Woolwich and Custom House are to follow.
Main tunnels
On the tunnelling side Crossrail will involve five main drives packaged into three contracts, the first of which is the Royal Oak to Farringdon section expected to commence in October 2011. Known as package 300 the western running tunnels contract involves the construction of twin 6.2m diameter bored tunnels from Royal Oak (west of Paddington Station) through to the new Crossrail Farringdon Station. The length of the drive is approximately 6.2km including a crossover at Fisher Street. “The first of the tunnel boring machines will start out on its journey from Royal Oak towards Farringdon. This will be followed shortly by the launch of a further tunnel boring machine in Docklands that will head towards Farringdon under central London,” says Andy Mitchell, Crossrail programme director. This bore is expected to finish in March 2013.
The second contract is for package 305, the eastern running tunnels and this begins with the 8.3km bore of the 6.2m diameter tunnel from a portal at Limmo Peninsula through to the Crossrail station at Farringdon. The launch date is April 2012 and it is expected to take 24 months.
This contract also covers a 2.7km launch chamber at Stepney Green that runs through to the Pudding Mill Lane portal to begin in July 2013 and finish the following March. A further 0.9km launch chamber from Limmo Peninsular through to Victoria Dock portal is also part of this package and this is set to start in July 2014 for completion in December.
Five consortia have been shortlisted for these contracts and they include Balfour Beatty Civil Engineering with Morgan EST plc, Vinci Construction Grand Projets and Beton-und Monierbau Gesellschaft; a joint venture of Bam Nuttall, Ferrovial Agroman (UK) and Kier Construction (Team BFK); Costain with Skanska Construction UK and Bilfinger Berger Civil (Ingeneirbau); a joint venture of Spain’s Dragados and John Sisk & Son (Holdings); and finally a joint venture comprising Laing O’Rourke Construction and France’s Bouygues Travaux Publics. Expressions of interest have also been invited for the third and final tunnelling package, contract 310, which involves construction of 6.2m diameter twin bores from Plumstead to North Woolwich. The 2.6km length will begin in September 2012 for completion in October 2014. Although this is a short section the work is expected to be challenging as the excavation will be conducted in Thames Chalk and it runs beneath the river. Contractors are expected to suggest the use of a slurry bore for this section. For the other four bores contractors are likely to use EPB machines for the works, which are mainly in London Clay. Compensation grouting is also expected to be a necessity thanks to the proximity and density of existing structures along the routes.
Mucking out
In total over 8 million m3 of spoil will be excavated to sites at Westbourne Park near Paddington and Limmo Peninsula near Canning Town. The Crossrail team is promoting re-use of the spoil and has a number of projects planned for the fill. At Wallasea Island on the Essex Coast the RSPB is submitting a planning application to Essex County Council for a project to raise the land, create hillocks and dips using Crossrail material. The new landscape will allow the collection and flow of seawater and improve bird habitats.
Other material is to be removed via rail and water with excavated material being transported by barge from Instone Wharf on the River Lee, Isle of Dogs station, and Manor Wharf in the London Borough of Bexley. Rail movements will be taken from Royal Oak near Paddington. Material arising from the construction of stations and shafts will generally be removed by road transport. The final mode of transport will depend on the destination of the excavated material.
Despite its GBP 15.9bn price tag the UK government has remained committed to Crossrail with Mayor Boris Johnson giving it full support. However with a new government committed to cost cutting, the comprehensive spending review this autumn is expected to review all major expenditures. The Crossrail management team remains confident that it has priced the scheme as efficiently and appropriately as possible.
The six storey station at Canary Wharf will contain four floors of retail space and is being developed by Canary Wharf Group The first GBP 500M contract for development of Tottenham Court Road was awarded to Taylor Woodrow Construction with Bam Nuttall in December 2009 The new line has a total of 42km of bored tunnes
