By Lynda Myer
Considering that the news of storing two HS2 TBMs beneath Old Oak Common Station until the government gives the go-ahead for the Euston Tunnel was published in previous week, currently contractors are tackling the logistics.
According to transport secretary Mark Harper announcement in March, the government was prioritizing the high-speed line between Birmingham and Old Oak Common in west London, rather than the service running to Euston Station in central London, while the line between Birmingham, Crewe and Manchester would be delayed for two years.
Although in April, HS2 confirmed that work on Euston Station had also been deferred, the preparation works for the commission of the two TBMs for the Euston Tunnel is slated to continue.
Also, in order to allowing additional train tracks to be built over the top, with the Great Western main line to be widened as part of the Old Oak Common development, the two TBMs needed to be lowered into place next year, whereas last week HS2 told PA Media that HS2 passenger services were not due to begin for at least six years.
HS2 told T&TI the logistical constraints were the main technical challenge to storing the two Herrenknecht TBMs.
“The TBMs will be launched having been assembled in situ from the eastern end of the Old Oak Common Box. The east side of the box is currently being constructed by HS2’s station construction partner, BBVS, and will be handed to our London Tunnels contractor, SCS JV. Initially the team will receive the Atlas Road Logistics TBM which is currently constructing a logistics tunnel (ARLT) between the Atlas Road site and the East Box. Following that they will construct the launch adits for the Euston Tunnels. The Euston TBMs will be lowered and the box will then be handed back to BBVS construction work above the launch chamber,” a spokesperson said.
Due to the position of underground box between the operational Network Rail lines for GWR and the Elizabeth Line, and the Elizabeth Line maintenance depot, access is challenging.
The HS2 spokesperson also added: “This limits the size of cranes that can be used to lower the TBMs. Also, space dictates that only part of the TBM can be built in the box at the early stage and the gantries and services will be built via access through the ARLT. This will ultimately supply both the up and down line Euston TBMs with both lining segments to the TBMs and conveyor route for spoil removal from the TBMs.”
“Both the SCS JV and BBVS JV team have worked closely with each other to co-ordinate the work, ensuring it is sequenced correctly and that access can be granted with enough space for safe working. The team has been using 3D CAD modelling which helps identify potential issues that might arise,” stated HS2.
Following that the two Euston TBMs are in place, access is going to be via the ARLT and it will house a conveyor as well as the services the TBMs will require.
“The tunnel will also be used by the multi service vehicles which will deliver the tunnel segments. The construction team will access along this route. There will be no services from the surface at Old Oak Common except for an aperture for ventilation,” the HS2 spokesperson said.
The two TBMs will be named and blessed before being lowered and stored.
