HS2 is the biggest infrastructure project in Europe and it is remarkable how rapid the progress has been from conception to the verge of construction.
It is on course for enactment at the end of this year and the start of construction next year, with the first phase from London to Birmingham to open in 2026, just 16 years from conception.
It is not just the rate of progress that stands out from the past six years but the integrity of the case for HS2, which has withstood fierce debate and cross-examination.
From the outset, the central argument for HS2 has been about capacity, with speed and connectivity as significant additional benefits.
Since 2010 the imperative for more capacity has become greater still, which is essentially why HS2 has withstood scrutiny and controversy.
It could not be more vital to our economic future. Rail demand has doubled in the past 15 years alone. HS2 does not just meet this demand for intercity travel; by freeing up substantial capacity on the existing lines, it provides a major capacity boost for freight trains and passenger services.
From the outset, the big question underpinning HS2 has been: if not HS2, what? The last upgrade of the West Coast Main Line cost £9 billion, £1bn of which was simply to pay train operators for not running trains due to the disruption in a decade of constant upheaval.
Upgrading a busy main-line railway is like conducting open-heart surgery on a moving patient. To put this in perspective, the present government identified an upgrade alternative to HS2 from London to Birmingham, Manchester and Leeds in their 2013 strategic case.
This upgrade cost nearly half as much as HS2 but provided only a quarter of the extra capacity.
The argument on faster journey times has also become clearer over time.
As HS2 proceeds further north, the time savings become steadily greater: an hour off every journey between London and Manchester, Sheffield and Leeds.
Critically, however, HS2 dramatically improves connections between cities within the North itself.
The Victorian railway companies built mostly separate main lines from provincial cities to London, which is why rail links between most of our provincial cities remain very poor. Birmingham and Manchester are only 67 miles apart, yet the rail journey time between them takes one and a half hours. It will be 40 minutes by HS2.
Sheffield to Manchester could be reduced to 30 minutes by HS2, if it is incorporated as part of the second phase, making this a key part of what is now being called HS3 – the proposed upgrading of rail links between the Northern cities.
Of course there are major challenges ahead, not least in keeping HS2 to time and to budget, but we are right to be taking it forward.
n Andrew Adonis spoke in a Lords debate.
This is an edited version.