21.09.17
Crossrail: track installation complete
Source: RTM Aug/Sep 17
Chris Enoch, Crossrail’s railway systems project manager, discusses the complexities in the design and installation of the track system on the Elizabeth Line project.
This summer, the Crossrail programme reached another exciting and momentous milestone. Over 50km of brand new track has been installed between Westbourne Park in the west through to Plumstead and Pudding Mill Lane in the east. This completes the tracklaying for the central tunnelled sections and interconnecting open sections of the new Elizabeth Line railway.
Following an intense period of design and procurement activity, track construction commenced two years ago with 3km of direct fixed track being installed through the 140-year-old Connaught Tunnel. This was a highly manual operation, requiring significant numbers of logistics, concreting and surveying teams. The completion of the temporary railhead at Plumstead, where a diverse fleet of engineering works trains were stabled and serviced, also enabled construction of the standard track slab (STS) to proceed, heading west towards central London.
STS accounts for over 80% of the track that has been laid on the Crossrail project. It comprises advanced HP rail (manufactured by British Steel in Scunthorpe), a twin-booted sleeper system and fibre-reinforced concrete. Over 63,000 sleepers and 51,419 metres of rail have been installed, along with more than 800 sections of long welded rail (LWR) which were progressively transported by train from Scunthorpe to site in 108 metre lengths. The 465-metre-long concreting train – a dedicated concreting batching plant on rail – was deployed by ATC, the main joint venture contractor delivering the railway systems works on the project, in August 2015. This highly sophisticated train was key to the STS tracklaying works as it blended, pumped and quality-assured its own concrete as it transited through the tunnels under London. At its peak, the concreting train delivered over 350 linear metres in one shift. The dedicated track team worked 24/7, constructing and setting out the track by day and concreting it by night – the train utilised the track that was constructed the previous night to make the next pour.
More than 3,600 metres of a highly advanced and specialist track form called floating track slab (FTS) has also been laid beneath areas that are particularly sensitive to noise and vibration at the surface, such as the Barbican, with its theatres and recording studios. The FTS comprises a series of extensive rebar cages, some 50 metres in length, constructed within the tunnel. A range of pressure-absorbing bearers sit within the cages, which have been concreted with an incredibly dense, unique concrete from a London batching plant. Concrete was pumped via Bond Street station and a new, dedicated shaft constructed at Hayne Street, near Farringdon. Concrete was pumped down the shaft and laterally along the tunnel to the FTS work faces to distances of up to 1.2km.
During this year, track construction proceeded from Westbourne Park (near Paddington) heading east to ultimately meet the FTS areas in the centre, near Bond Street. Concrete was sourced from a local batching plant and delivered to the workface via a dedicated concrete shuttle system.
As the track became progressively complete, it was used by an increasing number of engineering trains to complete other critical works, such as cable (> 1 million metres), fire mains (42km), drainage, overhead line, walkways and platform screen door installation. This dramatically increased the logistical challenges of completing the track work as multiple trades competed for the same access. Regular planning and logistics reviews and utilising state-of-the-art time/chainage tools enabled optimal planning and prioritisation.
The design and installation of the track system on the Crossrail project has been far more complex than many would, or could, imagine. The team has built a state-of-the-art railway under the heart of London and I’m immensely proud of the 500+ dedicated men and women who have worked towards the creation of the new Elizabeth Line that will serve passengers for decades to come.
FOR MORE INFORMATION
W: www.crossrail.co.uk