First two TBMs for HS2 London route ordered 09 Oct 2020

Jonathan Rowland, TunnelTalk
Fig 1. HS2 tunnels will run 20.5km under London
Fig 1. HS2 tunnels will run 20.5km under London
Fig 2. Launch and retrieval of the six HS2 London tunnel drives
Fig 2. Launch and retrieval of the six HS2 London tunnel drives

TBMs to drive an 8km x 8.8m i.d. section of the 13.5km twin-bore HS2 Northolt tunnel under London have been ordered from Herrenknecht by main works contractor JV Skanska-Costain-Strabag. The two EPBMs will excavate the western section of the Northolt alignment between West Ruislip and Green Park Way where a retrieval shaft will be constructed (Fig 1). They will erect a segmental lining in rings of seven segments. In efforts to speed segment handling logistics, the contractor has introduced a system for automatic segment transfer for unloading segment from the transporter to the backup gantries and to the ring-building areas. The machines will also have assisted ring-building capabilities to increase the level of automation of the TBM.

Two additional TBMs, yet to be procured, will be used to drive the remaining 5.5km x 8.1m i.d. eastern section of the Northolt route between Old Oak Common station and Green Park Way. Tendering for TBM procurement on this section is expected in early 2021.

The first two TBMs are expected to arrive on site at the end of 2021. Excavation will begin by mid-2022 for completion in early 2024. The machines have a cutterhead diameter of 9.84m, slightly smaller than the 10.26m TBMs procured from Herrenknecht for the twin 16km long HS2 alignment through the Chilterns. The Northolt TBMs will bore through mixed ground conditions that include London Clay and chalk. The machines will have a spherical main bearing to enable translation and tilting of the cutterhead. Extra details about the design and capabilities of the TBMs are being researched for future reporting.

A second 7.2km x 7.5m i.d. twin-bore alignment will run between Euston and Old Oak Common. Two additional TBMs will excavate this element of the project, bringing the total to six to complete the 20.5km of twin tube alignment for a total of 41km of HS2 tunnelling under London. Tending for these final two TBMs is expected in late 2021.


First three HS2 TBMs ordered and in manufacture 28 May 2020

TunnelTalk reporting

The first three TBMs to be used on the HS2 high speed rail project in the UK are on order and in fabrication at the Herrenknecht factory in Germany. These three TBMs, as the first of a total 10 TBMs needed for the project, are on order by the Align JV, of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick for central contract package C1, and by the BBV Balfour Beatty Vinci JV on its contract packages N1 and N2 at the north end of the line. The first two machines to be delivered later in 2020 are 10.26m in diameter and will be used by the Align JV to excavate the 16km long twin tube tunnels through the Chiltern Hills running northwest from just inside the M25m orbital motorway around London to South Heath in Buckinghamshire. The third machine for the BBV JV, is one of two machines it will need for excavation of the 2.8km long twin tube tunnel on the approach to the new Birmingham International Station. All three TBMs are of the Herrenknecht variable density slurry design.

First two HS2 TBMs in manufacture by Herrrenknecht in Germany for the Chiltern Hills drives

The two 170m long, 2,000 tonne, variable density machines for the Align JV will spend about three and half years excavating the Chiltern tunnels, which are the longest and deepest on the HS2 Phase 1 route from the Euston Station terminus in London to the Curzon Street Station terminus in Birmingham. They are programmed to work on a 24 hour, seven days a week schedule, stopping only for the end of year and public holidays.

First two TBMs will progress under the Chiltern Hills
First two TBMs will progress under the Chiltern Hills

The tunnels run up to 80m below the Chilterns working mainly through chalk geology with a reach of chalk with hard flint inclusions at the north ned. As the machines progress they will erect a segmental lining to 9.1m i.d. in rings of 2m wide. About 112,000 segments, each weighing about 8.5 tonne on average, will be required to complete the total 34km of the 17km long twin running tunnels.

About 56km of the 215km long high-speed railway line from London to Birmingham will be in tunnels. For excavation of these tunnels, BBV will oreder a second TBM for its twin tube drives in Birmingham and the SCS Skanska, Costain, Strabag JV will require six TBMs, two for excavation of the 7km-long Euston tunnels between Euston and Old Oak Common Stations in London and another four for the 14km-long Northolt Tunnels on its contract packages S1 and S2.

In contract packages C2 and C3 by the EKFB, Eiffage, Kier, Ferrovial, BAM Nuttall JV there is the green tunnel which is planned as a cut and cover operation.

About 56km of the 215km route is underground (in black)
About 56km of the 215km route is underground (in black)

In industry tradition, and in honour of Santa Barbara as the patron saint of miners and tunnellers, the TBMs will be given female names ahead of launch. In a competition among pupils of local schools, the first two TBMs will be named after a short list of three famous women: Cecilia Payne-Gaposchkin, the astronomer and astrophysicist born in Buckinghamshire who became Chair of Astronomy at Harvard University in the USA; Florence Nightingale, the founder of modern nursing, who spent many years in Claydon, Buckinghamshire where she wrote numerous books on nursing; and Marie Curie, the first woman to win a Nobel Prize, and the first person and the only woman to win the Nobel Prize twice.

The suppliers and names of the additional TBMs to be employed on the £35-45 billion Phase 1 project will be reported as the information becomes known and confirmed. TunnelTalk is prepared to continue its coverage of this important project into and through construction, and on to the programmed phased opening of full line between 2029 and 2036.


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