An 11,000 tonne curved concrete box is pushed under the East Coast Main Line near Peterborough 'in a first for UK engineering'.

The link also has the video of the operation. Similar construction method already has been performed several times in The Netherlands, by the way.

https://www.constructionenquirer.com/2021/01/27/morgan-sindall-pushes-11000-tonne-tunnel-video/