Production of concrete segments used to construct HS2’s 5-mile Northolt Tunnel has been completed in a major milestone for subcontractor PACADAR UK.
The company began work on the production of the segments in April 2022 and have completed the production of 59,129 segments, which make up 8,447 tunnel rings – seven segments per ring.
The segments are installed by the Tunnel Boring Machines (TBMs) after the ground has been excavated, creating the inner and outer lining of the tunnel. The segments are fed to the segment erector through the back of the machine and are installed through automation, reducing safety risks for the tunnel engineers.
Each segment weighs 7 tonnes on average and 130 precast segments have been produced daily by the Kent based factory.
HS2’s London Tunnels contractor, Skanska Costain STRABG joint venture, is constructing the Northolt Tunnel West which runs from West Ruislip to Green Park Way in Greenford. So far, the two TBMs constructing the twin bore tunnel have travelled almost four miles and have installed 6,550 of the PACADAR produced rings.
Malcolm Codling, HS2’s Project Client for the London Tunnels, said:
“We are making significant progress on constructing HS2’s London Tunnels and the work is a team effort across a number of contractors, including PACADAR UK. We are pleased to work with UK based companies to complete the Britain’s newest high-speed railway”
As part of HS2’s commitment to reduce the environmental impacts of construction, rail sidings were brought into use once space on site became available after the initial launch of the TBMs. The segments are now transported by rail from Kent to West Ruislip – with each train removing 56 lorries from the roads.
The final segment was cast by the on-site team in June 2024 step process on site. The team includes husband and wife, Loubna and Saad who are part of the 180 people working on site daily.
Antonio Díez Barral, Project Manager, PACADAR UK, said:
“PACADAR UK are immensely proud of this milestone and grateful to be awarded such an important contract. Working jointly with Skanska Costain STRABAG JV, PACADAR has brought state of the art construction method in order to optimise the use of materials, reduction of time and therefore remarkable savings and carbon footprint drop, all while creating a safe environment for all the 180 workers.”
James Richardson, Managing Director of Skanksa Costain STRABAG joint venture, said:
"This is an important step in the programme as we continue tunnelling underneath London using four tunnel boring machines. As we power ahead with building Britain's new high-speed line, we're thankful to PACADAR, for their knowhow and innovation to produce the concrete segments being used to construct the 5 mile Northolt Tunnel West."
PACADAR UK continue to work on other aspects of the HS2 project, including pre-casting segments for the Thame Valley Viaduct in Buckinghamshire and Edgcote Viaduct in Northamptonshire.
