To be honest, I rather agree with all of this. The area around Queensbury is hilly, and a cycle path going from the middle of nowhere to nowhere else very much is a bit of a tall order. The local geology is coal measures capped with flagstone, so no real hope there of being able to cut out to anything stable. The whole lot is unstable shale interspersed with thin layers of coal, so all manner of problems arise from there.I'm not sure which tunnel reopening appeal is more bonkers....Queensbury or Rhondda?
£35 million for a cycle tunnel from nowhere to nowhere, on a tunnel that encountered continuous problems from the start of construction and ended up filled with 15 million litres of murky soup, with dangerously weakened shafts close to built up areas (that would need to somehow be repaired to prevent cyclists flopping off their bikes from low oxygen levels).
Really, the best thing to do is back-fill the entire thing with as stable a rubble mix as can be found then pump in grout to try and further firm all of that up.