From tunnelling to tracks, meet the new fleet of machines fitting out the Crossrail tunnels
FITTING OUT THE RAILWAY
Crossrail is now focussed on the complex task of fitting out the new tunnels and stations with the necessary infrastructure and railway systems to enable TfL-run services to commence through central London and Docklands in December 2018. This includes the installation of track, tunnel ventilation, high voltage power, traction power, signalling, communications and overhead line equipment.
A fleet of bespoke machines will be used in the fit-out of the tunnels. Four giant multi-purpose gantries – which have been specifically designed for Crossrail - will carry and locate the track in the tunnels, before it is concreted into place.
Crossrail’s electric trains will be powered by overhead lines on the surface sections of the route and by an overhead catenary system in the new tunnels. Full height platform screens which will incorporate passenger information displays will also be installed at the new central section stations.
CROSSRAIL RAILHEADS - RAILWAY SYSTEMS LOGISTICS CENTRES
The two main temporary logistics centres for Crossrail’s railway systems are located at Plumstead in southeast London and Westbourne Park in west London. These are being used by the many different engineering trains during the fit-out of the tunnels and stations.
Plumstead is the larger of the two railheads with a total of eight tracks, an overhead gantry crane to supply engineering trains and an operations centre to coordinate the activity.
At Westbourne Park, the previous railhead that was constructed for the transport of excavated material from the western tunnels is being replaced with a new three-track railhead. The materials needed for the western tunnels fit-out will be stored and loaded onto construction trains at a temporary storage depot at Old Oak Common and brought to the Westbourne Park railhead.
INSTALLING THE TRACKS
Crossrail will use 5 different types of track in its tunnels:
- Standard track slab: this forms 80% of track on Crossrail’s central section
- Direct fixed track: used in the Victorian engineered Connaught Tunnel
- High attenuation sleepers: similar to standard slab, used only in a few small areas to reduce noise/vibration
- Floating track slab light: used to reduce noise and vibration underneath Soho
- Floating track slab heavy: used to reduce noise and vibration underneath the Barbican
The majority of the track in the central section is formed from standard track slab. This will connect with the other track forms that will be used at specific locations. A total of 41.2 km of standard track slab will be installed on Crossrail using fibre reinforced concrete.
Direct fixed track has been used within Connaught Tunnel. The track bed is a concrete reinforced structure. It allows engineers to create a flat surface on top of the significant undulations in the ground and to work within the height restrictions which are a feature of this Victorian engineered tunnel. A total of 2.6 km of direct fixed track has already been installed on Crossrail.
Floating track slab (light) will be used between Tottenham Court Road and Bond Street to minimise noise and vibration impacts from the operating railway on nearby recording studios and hotels which is a requirement of the Crossrail Act.
The track slab floats on a combination of elastomet rubber bearings and heavy duty springs. The track slab is constructed and then jacked up to accommodate the bearings and springs. A total of 1.97 km of floating track slab (light) will be installed on Crossrail.
Floating track slab (heavy) will be used in the Farringdon area due to the close proximity of the Barbican. It sits on heavy duty springs. A total of 1.34 km of floating track slab (heavy) will be installed on Crossrail.
Due to the extra depth added by the spring base of the floating track, a shallower sleeper is needed. To ensure that the shallower sleeper remains durable and effectively minimises noise and vibration, an incredibly dense concrete called Magnadense is used. Magnadense is over twice as dense as normal concrete due to its natural iron ore content.
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