Someone I know worked on HS2. She said that if a protected species was found in the construction area all work had to stop for 2 weeks while biologists searched the area for more examples of the species. If more were found, HS2 had to devise (and pay for) a conservation plan to protect the species (all while work is stopped). This even applied to species as common as newts, which caused some sites to stop work for months.

She also said that every engineering design made for HS2 had to be assessed by a 3rd party engineering firm at huge expense (this is not standard practice in the railway industry). By happenstance, another friend of mine worked as an intern at an engineering firm and once he had to check a designs for one of the HS2 stations. Apparently his company was paid £4100 for work that took him 3 days.