By rosebell
Following permanent construction to form the walls of the box was commenced in June 2021, excavation of the box structure at HS2’s Old Oak Common station in west London was started and it has been completed during three years.
Including a 1.8km-long fibre-reinforced concrete diaphragm wall around it, the vast underground box hasand caused remove of 1.3 million tonnes of London clay.
Completion of the digging process was up to HS2’s station construction partner, Balfour Beatty Vinci Systra joint venture (BBVS JV), working with specialist structures contractor Expanded. The project’s 1,500th apprentice, 19-year-old Miguel Jardim, removed the last of the London clay from the box, whereas HS2 says it is on track to meet its target of 2,000 apprenticeships.
Starting from the west and the east of the structure, excavation was completed section by section within the box and met in the middle.
With 20m deep, a reinforced concrete base slab up to 2m deep is being poured through this box and the number of steel rebar, assembled by hand on site, that have been used in the box, alongside 160 reinforced concrete columns which have been installed inside the outer wall to help support the structure, is almost 32,000 tonnes.
HS2 says all the steel used was responsibly sourced and most of the concrete is produced by the London Concrete batching plant on site, which reuses rainwater in its mixes. Now the box has been excavated, the team will pour the final sections of base slab to fully complete the box.
In order to presnting HS2 services, six 450m platforms will be constructed in the underground box, while above ground, eight further platforms are being built, and are due to be served by the Elizabeth Line, Great Western Mainline services and the Heathrow Express. Being linked to more than 170 destinations on the UK’s railway network directly, Old Oak Common station will become one of the country’s most vital transport hubs.
According to HS2 Ltd’s head of delivery, Sam Clark: “The tremendous progress made by our construction team to complete the excavation of the box is an exciting milestone for the project as it signals the next phase of construction where high-speed platforms will be built, as well as the station building itself.”
Using conveyor to the nearby London Logistics Hub, which managed by Skanska Costain Strabag (SCS JV), the excavated London clay has been removed from site and for reusing sites in Kent, Warwickshire and Cambridgeshire, it has been transported by rail.
Considering that the Old Oak Common station conveyor has removed over 75,000 lorries from the road since November 2022, coinciding with the digging of the box, HS2 has decommissioned thisconveyor, whereas further spurs of the conveyor being used for HS2’s tunnelling operation in the area remain in use.
While preparing to construct HS2’s running tunnel to Euston, the east end of the underground box has been awarded to HS2’s London Tunnels contractor, SCS JV and two TBMs are slated to be lowered into the underground box later this year, before the station team starts building the station’s roof structure. Timings and funding for the construction of the Euston Tunnel are being confirmed with the government.
Old Oak Common will be the temporary terminus in the capital, once the HS2 inaugurated, while plans to transform the wider area around the station, a former railway and industrial site, are being led by the Old Oak and Park Royal Development Corporation. Plans are in place to deliver 25,000 new homes and 56,000 new jobs in the area surrounding the station.
