Comment by ipaddr

"They pick a year in the future - 2045, say - and ask: what should the national train timetable look like then, if we want to meet our national objectives as a country"

The agile way. You end up getting nothing you really wanted done but everything is on time vs the method where you get everything you want at some unknown point in time.

What if it was done waterfall style where you put in as much in the time frame and released at random marketing moments.