Heathow to Northolt trains?

[WideRanger]

One of the proposals that has been mentioned in the past (largely in the scenario if Heathrow is not ultimately extended) would be to reopen Northolt to commercial flights, and operate it like a satellite for Heathrow for short-haul flights just within the UK and Ireland common travel zone. For the sake of this thread, I'm not interested in the rights or wrongs of this idea, or about whether or not Heathrow should be extended.

But I have been thinking for a while about how Heathrow and Northolt could be connected if such an idea were to take hold. I would think that some kind of mass transport solution would be needed. I had thought about something along the A312 corridor. But that looks pretty difficult without causing major disruption to housing at some points on the route, and would surely be pretty expensive given that it would require a lot of new infratructure.

Seperate threads about Heathrow Southern extensions has made me think about whether the following could work.

Terminal 4 (or 5) - Terminal 2,3 - Hayes (on the Heathrow Link) - Hanwell (on the Relief Lines) - Greenford Branch - Acton& Northolt Line (non LU tracks) - dive back under the Central Line and then along an alignment to RAF Northolt via somewhere like the Polish War Memorial.

Could a non-stop (or perhaps single stop at somewhere on CrossRail such as Hayes and Harlington) service work among other services on those streches, at something like a 4tph frequency? Realistically, could the journey be made fast enough so that (from a air passenger point of view) it could feel like a seemless interchange? Could it be extended south of Terminal 4?

 

[30907]

Using Northolt is new to me, and an interesting thought.
As to the route, the GWML bit would be congested (freight as well as Crossrail) but not impossibly so, but it is indirect and therefore slow; I don't think it would work.
It's a shame that the GW Uxbridge branch has been pretty much obliterated...

 

[PTR 444]

As Northolt is pretty much next to HS2 anyway, you could have trains stop there instead of OOC, then run a monorail from there to Heathrow.

 

[AlbertBeale]

I'm loathe to join the fun, since I want airport capacity to be de-developed, not developed! But...

Having spent a lot of my life on and around the A312 - many many years ago - I'd not think of trying to find a way to put any tracks anywhere near that alignment, even in my most crayonista moments.

Certainly Heathrow-Hayes-Greenford-Northolt, though rather a loop, and with possible capacity problems, is a neat way of getting close to Northolt airport. But then ...turn off just before the Chiltern Line joins, and cut down to the Polish War Memorial, and in from the Western Avenue side, as suggested, is the nearest to a feasible route I'd guess. Or stay with the route and turn left after Ruislip Gardens (by the Central Line sidings) and access the airfield from the rear, so to speak.

I suppose if that was operated as an "inside the airport" link, with an end-to-end time of no more than 15 minutes or so (feasible if the GWML pathing worked out - not to mention interleaving with the local trains through Castle Bar Park etc [I know locals who'd never let that service die!]), then it wouldn't be completely impossible. I'm sure there are airport terminal interconnections around the world which are no quicker!

(NB the idea of linking Heathrow with Northolt for extra capacity isn't new - it's been around on and off for years.)