What's the background?
A new high-speed railway, known as HS2, is being constructed between London and the North.
However, some are against the £106bn plan - claiming it is the "most expensive, wasteful and destructive project in UK history" and that it is "set to destroy or irreparably damage 108 ancient woodlands and 693 wildlife sites".
However, bosses at HS2 have said seven million trees s will be planted during the opening phase of the project and that much ancient woodland will "remain intact", according to BBC News.
Find out more about the project, and arguments for and against it, on this Newsround page.
What's happening now?
According to BBC News, campaigners spent months digging the tunnel they claim is 100ft (30m) long to protest against the railway's construction. Since August, HS2 Rebellion members have been living in tree houses and tents at a camp nearby.
Now, HS2 have started to evict activists who dug the tunnel near Euston station. A HS2 spokeswoman said the protesters were "trespassing" on land owned by the company.
- What's the aim of this protest?
- Why have protestors chose this method of protest?
- Do you think it will make a difference?