It's known that there is some interest from stakeholders to see a service using the north curve between Rickmansworth and Croxley once the Croxley Rail Link (CRL)/Metropolitan Line Extension (MLE) opens. There are also proposals to increase London Overground (LO) services on the DC line up to 4tph. This will result in a peak service between Watford High Street and Watford Junction of 10tph (4tph LO + 6tph Met). We also know that the line south of Harrow & Wealdstone will have to manage 14tph (4tph LO + 10tph Bakerloo).
With that in mind, does anyone know the signalling capacity of the section of line between Watford High Street junction and Watford Junction, (bearing in mind WHSj is a flat junction), and thus how much capacity will remain available to increase services further, i.e. to provide the aforementioned north curve service?
Moving beyond that, a few days ago my attention was drawn back to the Chiltern service between Aylesbury and Harrow-on-the-Hill in a discussion about improving capacity there. Fundamentally, I suspect longer trains are required, which means platform extensions at the very least at the major stations - Aylesbury, Amersham, Rickmansworth and HotH. Thinking about the two issues in the wider sense the disused bay at Rickmansworth got me thinking - if you lengthened the platforms eastwards to 8x20m-car length, the bay would because suitable for a 4-car service. A parallel single track section from the bay to Watford north curve could enable a 4-car shuttle service to operate without impacting capacity on the double track section between Rickmansworth and the Watford junctions. It would mean a change at Rickmansworth, but it would keep things simple. Question is whether there would be capacity for it between WHSj and Watford Junction?
Looking further ahead, what is the capacity like on the Chiltern services from Aylesbury via Amersham? Anecdotally I hear they're pretty overcrowded despite many choosing to drive over to the WCML for better service. I ask mainly because the next step to increasing capacity would obviously be to add more signalling, but if that's as good as it gets, then adding more tracks becomes the requirement, and four tracks to Chalfont & Latimer (C&L) from Watford South junction has few obstacles, but those it does have are Rickmansworth's and C&L's stations. Rebuilding those when they get their longer platforms could resolve that - Rickmansworth was going to be rebuilt in the New Works programme further east, on the straight section adjacent to the then goods yard (and now Waitrose), with 4 platforms (and 4 tracks!). Completing this as planned and extending it through Chorleywood (which has plenty of space) to C&L would enable the Met to provide a segregated service to Chesham, giving Chiltern segregated "fast" tracks all the way to Marylebone to operate as required, and going full circle, would enable the Met to provide a Chesham to Watford Junction service without impacting either Chiltern nor their mainline south of HotH at all (as it would just use the spare paths on the northern section used further south by Uxbridge services).
With that in mind, does anyone know the signalling capacity of the section of line between Watford High Street junction and Watford Junction, (bearing in mind WHSj is a flat junction), and thus how much capacity will remain available to increase services further, i.e. to provide the aforementioned north curve service?
Moving beyond that, a few days ago my attention was drawn back to the Chiltern service between Aylesbury and Harrow-on-the-Hill in a discussion about improving capacity there. Fundamentally, I suspect longer trains are required, which means platform extensions at the very least at the major stations - Aylesbury, Amersham, Rickmansworth and HotH. Thinking about the two issues in the wider sense the disused bay at Rickmansworth got me thinking - if you lengthened the platforms eastwards to 8x20m-car length, the bay would because suitable for a 4-car service. A parallel single track section from the bay to Watford north curve could enable a 4-car shuttle service to operate without impacting capacity on the double track section between Rickmansworth and the Watford junctions. It would mean a change at Rickmansworth, but it would keep things simple. Question is whether there would be capacity for it between WHSj and Watford Junction?
Looking further ahead, what is the capacity like on the Chiltern services from Aylesbury via Amersham? Anecdotally I hear they're pretty overcrowded despite many choosing to drive over to the WCML for better service. I ask mainly because the next step to increasing capacity would obviously be to add more signalling, but if that's as good as it gets, then adding more tracks becomes the requirement, and four tracks to Chalfont & Latimer (C&L) from Watford South junction has few obstacles, but those it does have are Rickmansworth's and C&L's stations. Rebuilding those when they get their longer platforms could resolve that - Rickmansworth was going to be rebuilt in the New Works programme further east, on the straight section adjacent to the then goods yard (and now Waitrose), with 4 platforms (and 4 tracks!). Completing this as planned and extending it through Chorleywood (which has plenty of space) to C&L would enable the Met to provide a segregated service to Chesham, giving Chiltern segregated "fast" tracks all the way to Marylebone to operate as required, and going full circle, would enable the Met to provide a Chesham to Watford Junction service without impacting either Chiltern nor their mainline south of HotH at all (as it would just use the spare paths on the northern section used further south by Uxbridge services).
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