Construction work has started on the large subterranean concrete box that will eventually house the HS2 platforms at the new Old Oak Common station.
Work to construct the 850m-long station box at HS2’s Old Oak Common station began as the concrete frame and substructure specialist, Expanded, started on site. The station box is a reinforced concrete structure that will form the frame and base for the HS2 station building. When completed, the station box will be 850m long – the length of eight football pitches.
The construction method will see the side walls dug down around the box and the columns pushed down into the ground where needed, and then the ground floor will be cast in reinforced steel as a slab on the ground. They will then dig down underneath the concrete slab to excavate the soil down some 20 metres to the bottom, where the base slab will be poured.
This form of “top down” construction allows them to dig the box using the ground floor slab to hold the sides up without needing to use huge props to keep the side walls upright. Apart from that benefit, having the ground floor slab in place at the start of construction makes it possible to start above-ground building works even while the station box is being dug underground.
The muck being dug out of the ground for the station, and the tunnels will be shipped by rail to three locations – to fill in a disused pit near Cambridge for housing, landscaping at Cliffe in Kent, and landscaping a future nature reserve on the edges of Rugby.
The construction of the box at the east of the site will also allow the Tunnel boring machines (TBM) to be launched towards Euston later. The west of the site is where the spray concrete lined tunnel between Old Oak Common and the Victoria Road Crossover box finishes.
Once complete, Old Oak Common station will have 14 platforms and allow a mixture of six high-speed platforms in the subterranean box, and eight conventional service platforms for the Elizabeth line and National Rail on the surface.
When it opens, it’s expected that more than 90 million passengers per year using the station, which means this one HS2 railway station alone will handle more passengers than (pre-pandemic) Heathrow Airport.