Mismanagement aside, HS2 required 8000+ different permits along its route [1], as well as years of opposition and legal battles from environmental groups and NIMBYs.
This is a significant portion of the cost, huge amounts of 'green tunnels' and cuttings are being created where they are not needed.
[1] https://www.theguardian.com/uk-news/2024/nov/07/cost-of-shed...
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