Euston tunnel
 | |
| Overview | |
|---|---|
| Status | Under construction |
| System | High Speed 2 |
| Crosses | West London |
| Start | Euston railway station |
| End | Ruislip |
| Operation | |
| Traffic | Rail |
| Technical | |
| Length | 4.5 miles (7.2 km) |
| No. of tracks | 2 |
| Track gauge | 1,435 mm (4 ft 8+1⁄2 in) |
| Electrified | 25 kV 50 Hz AC |
| Width | 9.5 metres (31 ft) |
Euston tunnel is a tunnel currently under construction in London that will carry the High Speed 2 railway between Euston railway station and Runslip, near the future Old Oak Common railway station.
History
To bring the HS2 high speed line into London, it was decided that a series of twin-bore tunnels underneath the city would be the most practical approach.[1] These shall have a combined total of 26 miles, roughly equivalent in length to those built for the Crossrail programme. Responsibility for the construction of the section between central London and the M25 has been assigned to HS2’s main works contractor, Skanska Costain STRABAG JV. In total, it has been envisaged that there shall be ten tunnel boring machines (TBMs) used to bore the 64 miles of tunnelling along the HS2 route between the West Midlands and London.[1][2]
During October 2020, HS2 Ltd signed a contract with the manufacturing group Herrenknecht to build and supply the two TBMs for the Euston tunnel.[1] These are to be custom-designed to suit the local geology, which ground surveys indicated to be largely comprised of clay and chalk, with which the tunnels are to be bored through. Each TBM shall be 140m in length, headed by a 9.84m diameter cutter head, and shall weigh approximately 2,050 tonnes.[1] Delivery of the two TBMs was scheduled to take place sometime in late 2021.[1]
In early 2022, initial boring is expected to take place; this phase of the work is expected to take roughly two years to complete. Boring is set to proceed on a non-stop working pattern, only shutting down temporarily on Christmas and for bank holidays. During the excavation phase, it has been projected that 1.2 million cubic metres of spoil, weighing 2.46 million tonnes, shall be removed by the TBMs.[3][1]
Construction
The tunnel will be bored using tunnel boring machines launched from the western entrance, near Old Oak Common railway station.[1] The tunnel shall have a length of 4.5 miles (7.2 km) along with an outer diameter of 9.5 metres (31 ft). At its deepest point, the tunnel will run 50 metres (160 ft) below ground.[1]
The lining of the tunnel, which shall consist of pre-cast concrete sections, is to be manufactured in a factory on the Isle of Grain, Kent. These sections are to be transported to the construction site intact by rail.[3] Between August 2021 and December 2033, a portion of London Zoo's car park shall be temporarily borrowed for use by construction vehicles while Euston Tunnel is being built.[4]
One of the few above-surface elements of the tunnel shall be a three-storey building near to Euston railway station, adjacent to the existing West Coast Main Line, which shall accommodate a 12-metre diameter ventilation shaft from the surface to the twin tunnels below; this structure shall also facilitate emergency access to the tunnel along with supporting electrical plant rooms. The top of this building shall be covered by a green roof, stone-paved courtyard and have an entrance from Park Village East.[5][4]
References
- ^ a b c d e f g h "Giant tunnelling machines contract for London tunnels signed by HS2 Ltd". Global Railway Review. 12 October 2020. Retrieved 16 August 2021.
- ^ "London tunnels". hs2.org.uk. Retrieved 10 October 2021.
- ^ a b O'Connor, Rob (4 August 2021). "First tunnel segment contract award for HS2's London tunnels". Infrastructure Intelligence. Retrieved 16 August 2021.
- ^ a b "Euston approaches". hs2.org.uk. Retrieved 10 October 2021.
- ^ "Engineering brick cladding for HS2's Euston headhouse". The Construction Index. 17 February 2021. Retrieved 16 August 2021.
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