HS2 is a special case because it is augmenting the West Coast Main Line which runs at-capacity almost 24/7. You can't shut it down for 30 minutes at 3am, let al

HS2 is a special case because it is augmenting the West Coast Main Line which runs at-capacity almost 24/7. You can't shut it down for 30 minutes at 3am, let alone for years while it is replaced wholesale. To do it piece by piece would take either unfathomable amounts of money or several decades of piecework.