It's a bit of a process even so. Orders made by ministers will still need careful drafting, with all manner of studies into the usual environmental and equality stuff. When made, they are subject to judicial review. Incredible though it may seem, I bet someone will object to the reopening of the Portishead line, although only time will tell how far they will take it. It is unlikely to have a rough passage once started, though, something that probably won't be true of Bristol's BRT▸ (Bus Rapid Transit) plans.
To have truly comprehensive public transport needs a totalitarian regime, usually communist, happy to ride roughshod over anyone who objects.