Article date 14 October 2025

The Acton - Northolt line, formerly known as the New North Main Line, runs from Old Oak Common to Northolt. It used to be a dual track line and was formerly used for main line services from Paddington. In recent years it has been reduced to single line working.

At an early stage in the plans for High Speed 2 (HS2) the intention was to reuse this line as part of the HS2 line from Euston to the North. The plans were subsequently revised to not make use of this line, running in tunnel instead. An undertaking was given that the Acton - Northolt line would remain available, for example not being obstructed by tunnel ventilation shafts.

At the time of writing High Speed Two Limited is redeveloping Old Oak Common in order to build a High Speed 2 station. This is a lengthy process. It will also involve Network Rail relocating the tracks of the Great Western Main Line (GWML) to call at newly-constructed platforms. As part of this other tracks are being removed. There will also be new station stops on other local lines.

This video filmed in 2011 youtube.com/watch?v=BNsk4flp5yM
is for a parliamentary train from West Ruislip to Paddington. Since then the Elizabeth line has opened and which occupies the northernmost pair of lines of the Great Western Main Line (GWML). If this parliamentary train terminating at Paddington had continued to run it would have necessitated crossing the Elizabeth line. However there could have been the option of using the flyover to the east of the West London line. The flyover can be found on openstreetmap.org and Google to the east of Old Oak Common, located between Scrubs Lane A219 and Ladbroke Grove B450.

As part of the development by HS2 Ltd, the connection from the Acton - Northolt line to the GWML has been severed. The bridge over Old Oak Common Lane, which accommodated dual track, has been demolished. (HS2 Ltd uses the terminology Wycombe Line for the Acton - Northolt line.) This has taken place within the context of a West Midlands and Chilterns Route Study published in 2017 by Network Rail with technical appendices and which is available online. The proposal in the Network Rail study relevant to our discussion is to provide a Chiltern Main Line connection to Old Oak Common station, since Marylebone station has no potential for capacity upgrade. This would provide an interchange at Old Oak Common. HS2 is asked by Network Rail to accommodate this on a "not to preclude" mandate. The Acton - Northolt line would be restored to dual track terminating in one or more terminus platforms at Old Oak Common.

In terms of this mandate, it seems no thought was given to onwards connection for services to terminate at Paddington. With the existing GWML tracks being relocated, it would have been possible to request one or more through platforms, rather than terminus platforms, connecting on to a single track onto the flyover, this providing a means of connection to Paddington. This is our proposal.

Our proposal for onwards connection of the Acton - Northolt line to Paddington is within the context of our proposal for Aylesbury Interchange on HS2 which would benefit from it but this proposal also exists in its own right.

We will not list all possible uses of a connection of the Acton - Northolt line to Paddington. It is a rebuild of what was available previously. One previous use was for trains from Paddington to use a route via North Acton, the Greenford branch and Ealing to return to Paddington with the first class carriages at the other end of the train. Apparently this route has also been used for the balancing of wheel wear on Heathrow Express trains, there being a tight radius of track at Heathrow junction: en.wikipedia.org/wiki/Acton–Northolt_line.

From Paddington to Paddington would necessitate use of the flyover twice, once in each direction. On the return leg making use of the Elizabeth line eastwards there would be a crossing on to an adjacent track on the left thereby providing access to the flyover for the return to Paddington.

The remainder of this article provides further detail.

Had the Old Oak Common site not been subject to redevelopment to provide an HS2 station, it would have been possible to use existing tracks to connect the Acton - Northolt line onto the flyover for Paddington. Certainly tracks would have needed upgrading. Courtesy of Google, let us illustrate how this could have been achieved, westwards. Zoom in for details. The overlap varies. Each opens in a new window or tab.

Use of the flyover
Step 1
Step 2
Step 3
Step 4
Step 5
From step 5 to step 6 a small white item is in view, a dark area between the tracks and some greenery.
Step 6
Step 7 (some track has been lifted)
Line to Northolt

The proposal in the Network Rail West Midlands and Chilterns Route Study relevant to our discussion is Appendix 4 page 25. At the time of writing this is available at
https://data.docslib.org/img/072bdba18ee6d36d4415a9f885c3e879-25.jpg
Here are the illustrations:

Text from the Network Rail West Midlands and Chilterns Route Study Appendix 4 page 25 is reproduced later.

The bridge for the Acton - Northolt line over Old Oak Common Lane has been demolished. It accommodated dual track. These views are courtesy of Google.
first view eastwards
second view eastwards
first view westwards
second view westwards
view southwards

We appreciated these videos.

Old Oak Common's original station youtube.com/watch?v=5s3YnbSpUYU

North Acton contrasts youtube.com/watch?v=AnQ4GHLUwzs

Lineside views on the NNML youtube.com/watch?v=KWbpRQnBRKU

Train on the flyover youtube.com/watch?v=jj0_wBdAoIk at time 18:30, also available at youtube.com/watch?v=DcgT9HucSkw

At modernrailways.com/article/government-pauses-mml-electrification-york-capacity-works-and-dawlish-phase-5
the last sentence concludes "and retaining the option to connect the Chiltern main line to Old Oak Common station."

Maps were located by searching for HS2 route map. There is no facility to not pass beneath the GWML Up Relief viaduct at
https://assets.publishing.service.gov.uk/media/5a7f2c21ed915d74e33f4c78/C221-MMD-CV-DPP-010-201702-FPD.pdf
referenced from
https://www.gov.uk/government/publications/hs2-plan-and-profile-maps-post-house-of-commons-select-committee-2016-london-metropolitan
referenced from
https://www.gov.uk/government/publications/hs2-plan-and-profile-maps-london-to-the-west-midlands-index-and-key-plans
This does not seem to match the Network Rail concept sketch?

Our proposal for Aylesbury Interchange: Proposal for Aylesbury Interchange on High Speed 2

Here is the text reproduced from the Network Rail West Midlands and Chilterns Route Study Appendix 4 page 25.

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Old Oak Common connectivity

As identified in section 2 above, the strategic concept developed is to route trains to a new station terminus in theat Old Oak Common development area. This is to deliver capacity beyond that delivered through train lengthening required to meet demand in CP7 and beyond enabling demand to be met in 2043. An enhanced link to Old Oak Common is required to support this concept, comprising an upgrade of the existing ‘Wycombe single’ line. The single line would need to be enhanced to a two track railway in order to support a 4tph frequency with potential line speed improvements to support service operations into one or moreand two turnback platforms are required at Old Oak Common, depending on the number of services to support a 4tph service without creating capacity constraints elsewhere. Transport for London have undertaken demand modelling of this service with a target journey time of 8.5 minutes between Northolt Junction and Old Oak Common. If this output is to be delivered, the linespeed would require upgrading to 80mph. Assessments have been undertaken to identify modifications to track, signalling, structures and earthworks needed to deliver two line speed options on the Wycombe line: this upgrade including redoubling single track sections and increasing the linespeed. This has also been assessed against the possibility of a TfL-promoted scheme to open a new station at Park Royal providing an additional interchange between Chiltern Railways and LUL servuces.50mph and 90mph. Remodelling of Northolt Junction is also proposed to support the enhanced connection to the upgraded Wycombe line. The current track layout between South Ruislip and Northolt Junction is also a constraint as both Up and Down services accessing the Wycombe Single are required to use a single platform at South Ruislip. Junction layout alterations to allow Down trains to use the existing Down platform and access the Wycombe single are required in order to sustain a frequent service on the Wycombe single. Through engagement with the HS2 undertaking to develop a Crossrail-HS2 interchange at Old Oak Common, it has been possible to explore the practicality of constructing a Chilterns facility within the Old Oak Common development site, and a working concept has been developed based on preferred GWML options for Old Oak Common at the time of the study, which does not impact on the track layout required to support Crossrail services and does not impact on HS2 construction. The concept developed is dependent on a ‘not to preclude’ instruction within the Old Oak Common development remit. The key criteria for achieving the benefits to this scheme is to locate the Chilterns facility within the Old Oak Common ‘triangle’ bounded by the Northern limit of the GW Relief Line development, the Southern edge of the HS2 ‘box’, and the limit of existing housing development along Old Oak Common Lane to the West of the site. This location of a new Chilterns station will minimise walk times, and therefore interchange times, between Chilterns services and other rail services and providing the greatest connectivity. The option of locating the Chilterns facility to the West of Old Oak Common Lane was also examined, with the platforms between the GWML Relief Lines and the North London Line (overbridge); however, this location had the additional cost of an all- weather walkway between these platforms and the proposed Old Oak Common station as well as the dis-benefit of increased overall journey times for passengers interchanging from Chilterns services and was therefore discounted. There is also a trade-off between provision for future train lengthening beyond the current specification and impact on the Old Oak Common concept due to the increased land requirement.

Interventions to meet demand up to 2043

To meet forecast service levels up to 2043, capability analysis work indicates that significant sections of four tracking would be required between Princes Risborough and Northolt Junction. Such a major enhancement would require significant land take and impact properties and the environment in the area. This is considered too disruptive and unaffordable to be taken forward in this Route Study. To deliver incremental capacity improvements to meet the medium term demand, it is proposed that four track sections are constructed at Denham, Beaconsfield and Princes Risborough as the formation at these locations can accommodate additional track sections. These additional tracks effectively create platform loops through the station areas to enable faster trains to overtake stopping services. Further timetable study and development work is required to confirm these to be optimal locations to construct loops to add capacity to the Chiltern Main Line as this is dependent on timetable structure. These particular locations have been selected due to their relative practicability of construction.

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