This video looks at the complicated approach tunnels that will head towards Euston station, which will be constructed in a different way to Euston Tunnels. Building what is effectively a new mainline railway into the heart of London was always going to be fraught with challenges, but one particular 300m long section may prove to be one of the most challenging to build on the entire HS2 route. Such is the complexity of the approach tunnels leading to Euston.
The two tunnel boring machines, which are building the 7.2 km long tunnel, will create two tunnels with a diameter of 7.5 m and should reach their destination by mid-2027. However, they will never actually reach Euston. Instead, the TBMs will come to a stop almost a kilometer from the station throat. And unlike most of the other TBMs used for HS2 tunnels, they won’t have a visible breakthrough moment and will instead just come to a stop. The final 300 m will instead be constructed using mined tunnel techniques, which involves using relatively small plant machinery to painstakingly excavate the tunnel approximately 1 meter at a time.
SCSJV who have been tasked with constructing the approach will have to excavate three separate tunnels and the huge cavern. The cavern will be used to split the up or southbound line tunnel into two further tunnels which will head south to the surface while a northbound or downline tunnel will emerge between the two upline tunnels. This for all intents and purposes will create an underground great separated junction.
