A massive cavern that will allow HS2 trains to switch lines is to be built next to Old Oak Common, and works are about to start on constructing it.
The Victoria Road Crossover Box site is located to the west of where the new HS2 Old Oak Common station is being built, and the cavern will house a crossover track mechanism that will allow trains to switch between tracks, up to a design speed of 62 mph, on the approach and descent from Old Oak Common station.
The enabling works, of surrounding the site with sheet piling has now been completed, and they are now able to start digging down to create the huge hole in the ground for the crossover cavern.
Now that the ground is secured, they will dig deep trenches around the site, filled with concrete to create a diaphragm wall to support the sides, and then dig down to excavate the soil to the bottom of the box. Excavated material from the tunnels will be taken away by rail from the nearby Rail Logistics Hub.
The base slab of the crossover box will be supported by 77 piles which will be pushed 20 metres into the ground below the bottom of the crossover box.
Using the accepted International Method Of Measuring Things, the depth of the box is the equivalent to the height of six double-decker buses stacked on top of each other.
The site at Victoria Road is also currently being prepared to launch the Northolt Tunnel Boring Machines which will bore 3.4 miles north-west, as part of the construction of HS2’s 8.4-mile Northolt Tunnel.
When the railway is operational, the site will also be home to the Victoria Road Ancillary Shaft which will provide ventilation and emergency access to the rail line during operation. The shaft will have an internal diameter of 25 metres and will be constructed using precast rings at the top, and using a sprayed concrete lining technique at the bottom.
Above ground, the site is being earmarked for housing, and there is a proposal to extract heat from the crossover box caused by the trains passing through, to warm the houses above.