Crossrail has released video footage detailing completion of two thirds of the track fit out on the project.
Crossrail said that track installation in the east section running from Pudding Mill Lane to Stepney Green is now complete and, therefore, the focus is now shifting to fitting out the tunnel. This includes tunnel ventilation, high voltage power, traction power, signalling, communications and overhead line equipment.
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 41.2km of standard track slab will be installed on Crossrail using fibre reinforced concrete.
Direct fixed track has been used within Connaught Tunnel, a former disused rail tunnel in Docklands. 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 that are a feature of the Victorian engineered tunnel.
A total of 2.6km 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 1.97km 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 to the Barbican. The track sits on heavy duty springs. A total of 1.34km 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, a dense concrete called Magnadense is used. Magnadense is more than twice as dense as normal concrete due to its natural iron ore content.
Crossrail is using five different types of track in its tunnel:
- 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.