The article is about previous attempts to dig a tunnel, in the 19th century etc. Crossrail (now the Elizabeth Line) had an exhibition in London at some point.

The article is about previous attempts to dig a tunnel, in the 19th century etc. Crossrail (now the Elizabeth Line) had an exhibition in London at some point. The artifacts they'd dug up were from the stations and underground crossings, i.e. the traditionally-dug bits. The tunnel boring machine just crushes everything. (And for that line is mostly deeper than artifacts anyway.)