Seth Godwin recently published a post about Unexpected Turbulence
It’s hard to summarise a post that’s only four sentences long, but the final sentence struck me as being very relevant to the HS2 proposal:
If your plan will only succeed if there is no turbulence at any time, it’s probably not a very good plan (either that or you’re not going anywhere interesting.)
Unfortunately, the HS2 proposal was originally dependent on very high levels of growth, higher then any other industry prediction. Eventually HS2 Ltd reduced the growth rate, but simply extended the forecast period – which was already longer then would normally be used in forecasting – until they got to the magic ‘doubling of passenger numbers’ that they needed to make HS2 a proposal that would not be rejected out of hand.