The completion of the excavation at Old Oak Common propels the HS2 project into the next construction phase.
- After three years of laborious effort, the underground box structure at Old Oak Common has been fully excavated.
- This 20-metre deep box, fortified by a substantial concrete diaphragm wall, hosts pivotal infrastructure for HS2.
- The site now transitions to the pouring of the final concrete slabs and preparation for the tunnel to Euston.
- This milestone is anticipated to drive significant economic and regional development impacts.
For three years, teams have toiled to excavate the significant underground box at Old Oak Common. Now fully realised, this step marks an important milestone in the ongoing construction of HS2’s new station in west London. The expansive structure, measuring 1.12 miles in circumference with a substantial fibre-reinforced concrete diaphragm wall, has required the removal of 1.3 million tonnes of London clay. The joint venture contractor, Balfour Beatty Vinci Systra (BBVS JV), alongside Expanded, a specialist structures contractor, orchestrated the excavation in sections, commencing from both the western and eastern flanks, culminating at the midpoint.
This vast 20-metre-deep structure is underpinned by a robust, reinforced concrete base slab that reaches up to two metres in thickness. Integral to its support system, approximately 32,000 tonnes of steel rebar were methodically assembled on site, supplemented by 160 reinforced concrete columns strategically positioned within the outer walls. These efforts underscore the extensive engineering work required to ensure both stability and durability of the structure.
Following this excavation, the focus shifts to the completion of the base slabs, a crucial element in transitioning to the next construction phase. At the eastern end, preparations are underway for HS2’s London Tunnels contractor, Skanska Costain Strabag (SCS JV), laying the groundwork for the impending construction of the HS2 tunnel to Euston. The deployment of two massive boring machines into the underground box is scheduled later in the year, signifying forthcoming developments.
The project’s forward momentum is not only a testament to the skilful execution by the teams involved but also signals significant socio-economic benefits. Sam Clark, head of delivery for HS2 Ltd, remarked on the progress: “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.”
Further, the site will integrate six 450-metre platforms dedicated to HS2 services within the box, while eight additional platforms intended for the Elizabeth Line, Great Western Mainline, and Heathrow Express will be constructed above ground. Additionally, significant amounts of excavated London Clay were efficiently relocated to reuse sites across Kent, Warwickshire, and Cambridgeshire, utilising a purpose-built conveyor system that has since been decommissioned.
The completion of the excavation heralds a transformative phase for the HS2 project at Old Oak Common, unlocking potential for expansive connectivity and growth.
