A tunnel boring machine used to dig part of the Elizabeth line has been used to build a tunnel for HS2 at the Old Oak Common station in west London.
The tunnel isn’t for HS2 trains, though, as those trains are even larger than Elizabeth line trains, but it links the Old Oak Common station site to the Atlas Road logistics site about a kilometre away, and linking the two in a tunnel means construction materials can be moved between the two without using the roads.
It will also — eventually – allow the spoil from the train tunnels to Euston to be removed from that tunnel even as the Old Oak Common station is in use elsewhere.
HS2’s London tunnels contractor, Skanska Costain STRABAG joint venture (SCS) constructed the logistics tunnel using a TBM repurposed using components from the machine used by Crossrail to dig tunnels from Limmo Peninsula in Canning Town to Royal Victoria Dock, and between Pudding Mill Lane and Stepney Green.
That TBM was called Ellie.
After she finished with Crossrail, the components were returned to the manufacturer, Herrenknecht in Germany, where they were refurbished for the slightly different soil conditions in west London. The TBM was also renamed, this time Lydia, after Lydia Gandaa, a former teacher at nearby Old Oak Common Primary School and a founding member of the Bubble & Squeak social enterprise in the area.
Launched from the Atlas Road site last year, it’s been digging the tunnel towards Old Oak Common, where it arrived this week.
Interestingly, thanks to the route the logistics tunnel had to take, it passed right underneath the Elizabeth line depot at Old Oak Common — which seems quite apt as it’s an ex-Crossrail machine digging the tunnel.
The TBM broke through into the eastern end of the Old Oak Common underground station box, currently under construction by a separate joint venture – Balfour Beatty Vinci SYSTRA (BBVS). Later this year, SCS will lower two additional TBMs into the box and assemble them so that they are ready to bring the HS2 line into Euston. Once they are in place, the box will be sealed so that the rest of the station can be completed — and the TBMs will be switched on when, or maybe if, the tunnels are dug to Euston.
Speaking about the milestone, Malcolm Codling, Project Client Director for HS2 said: “The completion of the Atlas Road Logistics Tunnel takes us closer along our journey to bring HS2 into central London at Euston. The logistics tunnel is a key part of our plans to enable us to construct the Euston Tunnel and will reduce the construction impact on the local community.”
Over the past nine months, TBM Lydia has removed 62,000 tonnes of London Clay, all of which is sent by rail for beneficial reuse across the UK and has installed 535 concrete rings. Pacadar UK manufactured the segments for the tunnel rings at its sits in Kent.
The logistics tunnel will deliver materials to the two Euston Tunnel TBMs, including over 56,000 concrete tunnel segments manufactured by STRABAG in Hartlepool, and take away the London Clay excavated.
The logistics tunnel will be backfilled once the Euston Tunnel is complete and the railway is operational. Unless someone finds an unexpected use for the tunnel, as looking after an empty tunnel costs money, if it’s not needed, it’s safer and cheaper to fill it back in again.