Here's a letter I sent to a magazine... I can't remember if they printed it.
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The proposed London Overground interchanges at Old Oak Common are inconvenient, and inadvisable for Heathrow passengers with luggage late at night. Problems:
1) The Southern service to and from the West Coast Mainline passes no platforms between Wembley and Shepherds Bush, and although platforms could be added at Willesden Junction, the route passes 450m from OOC and there are no plans for platforms there, leaving the southern WCML with no decent Heathrow route.
2) The West London Line Overground service operates as a branch of the North London Line, but this route between North London and West London is too circuitous to be much use: e.g. the TfL Journey Planner route for Camden Road to Shepherds Bush is usually to walk to Camden Town and get the tube, with no hint of the "direct" train. Keeping the WLL as part of the NLL allows disruption to spread between the two with little benefit.
3) The proposed West London Orbital service using the Dudding Hill line between Brent Cross West and Hounslow fails to interchange with the WLL, since the proposed OOC stations for the two lines are 900m apart.
4) Trains from OOC to the eastbound NLL would be quarter-hourly from each of two different stations 700m apart, both of which are 350m from the Crossrail station.
Solution: if the northern third of the West London Orbital became part of the WLL, and the southern two-thirds of the West London Orbital became part of the NLL, good interchange between the two could occur at Willesden Junction.
Trains from Brent Cross West could serve a new station at Craven Park before using a new curve near Harlesden Station down onto the Willesden Relief Lines used by the Southern service. After calling at a new platform at Willesden Junction, a new curve could take trains southwards and then straighten to allow WLL/Southern platforms passing under the proposed Hythe Road station (which would not be built). After the platforms, the line would curve east over the Great Western Mainline and then south to rejoin the current WLL/Southern alignment towards Shepherds Bush.
The NLL from Willesden Junction could use the current WLL curve towards the Hythe Road site, where it would curve south and west over the new WLL (twice) and over the GWML to new platforms along the south side of the Crossrail station, and then curve southward to rejoin the existing NLL alignment towards Acton Central. This would carry eight trains an hour in each direction, 4 between Stratford and Richmond and four between Stratford and Hounslow.
The WLL/Southern platforms would be tens of metres from the HS2 platforms and the NLL platforms would be tens of metres from the Crossrail platforms, allowing a unified safe station. Routes from Willesden High Level Junction to Acton Wells Junction and from West London Junction to Mitre Bridge Junction would probably be kept for freight, being flatter than the new routes.
This is more expensive than current plans! But the levelling of 2 square miles of land which is full of railways in slightly the wrong place is an opportunity that must be seized or we will regret it for a century.
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