TfN was a nice idea in practice. I think the rot set in when the elected mayors came on the scene, though, as it's clear they aren't going to be as amenable to deferring to a regional body in the way Cheshire East Council's leader would, for example. Which, as has been said above with "empire building" by the mayors is going to lead to a lack of focus.
And now that it seems to be that there's an established path for a regional mayor to become leader of a party and then Prime Minister (i.e. Boris Johnson, and clearly in the future it is the intention of Andy Burnham), there's a tendency to use everything as an opportunity to showboat and get media coverage, as opposed to do anything.
It was supposed to - in effect - take the role of the Department for Transport in the North. So hand out funding, oversee (and possibly even control) Trunk Roads, monitor the franchise agreements, etc.
Legally it has only existed since 2018, but the organisation was created in a "shadow" form in 2015 and was given a budget then.
In terms of Northern Powerhouse Rail / HS3, it was a mistake in the first place to give this to a regional body. Indeed there is disquiet in the government that nationally important strategic transport is outside their control in the devolved governments of Wales, Scotland and NI as is, so the idea of handing over something of this importance to the country to be controlled by Metro Mayors is unsurprisingly something they'd want to re-consider.
Meanwhile, whilst TfN were to take control of the Trunk Road network, the Metro Mayors themselves want to take control. Likewise the ticketing scheme. TfN is supposed to be implementing a ticketing scheme for the whole North of England, but the Metro Mayors aren't interested as they all have their own ideas and legacy historical ticket schemes.
Again, if you were the government, would you keep throwing money endlessly at a talking shop that is no closer to a ticketing scheme now in 2021 than it was in 2015, despite having had millions handed to it each year since then (£9 million in 2020/21 alone)?
The problem, in my view, is that George Osborne (who was the leading light in setting up), despite being an MP for a North of England constituency, didn't have the first clue about the region. He is on record as saying words to the effect of "TfL in London has Oyster cards and is making plans for Crossrail, so we'll set up TfN and they'll do the same in the North". But "the North" is not a homogeneous entity. (And when he said "the North", he really meant Liverpool-Manchester-Bradford-Leeds-Sheffield-Doncaster").
What I would do is as suggested by
@Bletchleyite - make it a PTE, or more precisely, I'd make it a PT
A. And remove the overall planning functions of the smaller transport areas in both City Regions and County Councils.
The local authorities and city regions would still get a say and sit on the committees (just as district councils get representation in Combined Authority areas, and councillors themselves sit on the transport committee in the County Councils).
The Combined Authorities would become the executive delivery arms in their areas (i.e. what the PT
E used to do), and in the shire county areas, the new authority can set up a delivery arm if it wishes (or needs to), or expand the areas of the Combined Authority delivery arms.
So in my plan, for example, "where do we want a new road", "should we fund re-opening this line", "should we open this station", "this is what ticketing zones we're going to have" would be for Transport for the North to decide.
"We need to clean these bus-stops", "we're letting a tender for the number 30 to go round the Westside Estate" or (in Greater Manchester) "we're monitoring the performance of Go North West in their four year franchise for Bolton bus routes" would be handled by e.g. Merseytravel, or Bee Network, or Transport for North Yorkshire as local delivery arms.
