Funding for Coryton passing loop: where might additional services go?

[positron]

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South Wales 'Metro' updates

I thought it would be worthwhile to start a discussion on the South Wales 'Metro'. Basically, this is the scheme to enhance transport links across south east Wales. One of the key issues that needs to be addressed is what form of transport will be used on the Cardiff Valley lines network -...

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Anna McMorrin MP

Fantastic to welcome Chancellor @RachelReevesMP to Cardiff North today, alongside @JoStevensLabour and @KenSkatesMS. We visited the @tfwrail depot in Taffs Well to see the new Metro trains in...

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Anna McMorrin MP:

excited about the potential this has to improve services in Cardiff North, including long-overdue upgrades to the Coryton line,

Not a confirmation but sure sounds like the £48m might be unofficially earmarked for a Coryton passing loop to get it to 4tph, which makes a lot of sense. Leaving Cardiff services at 2tph was always going to be a temporary measure to get it funded externally.

This does beg the question of where's the extra services going to go? Penarth? That'd surely need the passing loop on the Penarth line too?

 

[Cardiff123]

Anna McMorrin MP

Fantastic to welcome Chancellor @RachelReevesMP to Cardiff North today, alongside @JoStevensLabour and @KenSkatesMS. We visited the @tfwrail depot in Taffs Well to see the new Metro trains in...

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Not a confirmation but sure sounds like the £48m might be unofficially earmarked for a coryton passing loop to get it to 4tph which makes a lot of sense. Leaving Cardiff services at 2tph was always going to be a temporary measure to get it funded externally.

That's great but if there's no platform space at Cardiff Central for those services then they can't happen. You can't get anymore than 4tph up to Penarth, and if there's no capacity at Central, any extra Coryton services will have to go to Cardiff Bay, so will need to be operated by 398s.
If Cardiff West is remodelled, the remaining big constraints on any extra Cardiff area Metro services in future will be just 3 platforms at Central, the 2 track section between Central & Queen St and the 2 track bridge over Newport Rd.

 

[Caaardiff]

Anna McMorrin MP

Fantastic to welcome Chancellor @RachelReevesMP to Cardiff North today, alongside @JoStevensLabour and @KenSkatesMS. We visited the @tfwrail depot in Taffs Well to see the new Metro trains in...

www.facebook.com

Not a confirmation but sure sounds like the £48m might be unofficially earmarked for a coryton passing loop to get it to 4tph which makes a lot of sense. Leaving Cardiff services at 2tph was always going to be a temporary measure to get it funded externally. Does beg the question where's the extra services going to go? Penarth? That'd surely need the passing loop on the Penarth line too?

You'd think more people from North Cardiff would want to travel direct to Cardiff Bay than Penarth.

 

[positron]

That's great but if there's no platform space at Cardiff Central for those services then they can't happen. You can't get anymore than 4tph up to Penarth, and if there's no capacity at Central, any extra Coryton services will have to go to Cardiff Bay, so will need to be operated by 398s.
If Cardiff West is remodelled, the remaining big constraints on any extra Cardiff area Metro services in future will be just 3 platforms at Central, the 2 track section between Central & Queen St and the 2 track bridge over Newport Rd.

I'm curious why can't you get more than 4tph to Penarth? Assuming Cardiff west is fixed so you can get city line and VOG line services running a bit more efficiently?

Not saying 6tph Penarth would be a good idea but I'm curious why it wouldn't work?

I suspect it'll be Coryton - Central via the Bay and CrossRail line.

I agree Central is a capacity constraint but avoiding reversals on the valleys platforms (which 4tph on city will help with) should help with that a bit.

Hopefully CrossRail phase 2 where the central platforms are connected up west actually happens as that will help with capacity and resilience.

 

[AdamWW]

I'm curious why can't you get more than 4tph to Penarth? Assuming Cardiff west is fixed so you can get city line and VOG line services running a bit more efficiently?

Not saying 6tph Penarth would be a good idea but I'm curious why it wouldn't work?

I suspect it'll be Coryton - Central via the Bay and CrossRail line.

I agree Central is a capacity constraint but avoiding reversals on the valleys platforms (which 4tph on city will help with) should help with that a bit.

Hopefully CrossRail phase 2 where the central platforms are connected up west actually happens as that will help with capacity and resilience.

Maybe I've misremembered or been misinformed but I thought the original plan was for 2 trains per hour from Coryton to Penarth and another 2 trains per hour to Radyr via the City Line. Which I presume would need Cardiff West junction sorting out as well as a loop on the Coryton Line.

 

[Cardiff123]

I'm curious why can't you get more than 4tph to Penarth? Assuming Cardiff west is fixed so you can get city line and VOG line services running a bit more efficiently?

Not saying 6tph Penarth would be a good idea but I'm curious why it wouldn't work?

I suspect it'll be Coryton - Central via the Bay and CrossRail line.

I agree Central is a capacity constraint but avoiding reversals on the valleys platforms (which 4tph on city will help with) should help with that a bit.

Hopefully CrossRail phase 2 where the central platforms are connected up west actually happens as that will help with capacity and resilience.

6tph to Penarth is currently impossible as it's a single track line, and there are no firm, committed plans to install either a passing loop (originally planned from Dingle Rd to Penarth, but now dropped) or another platform at Penarth.
It's the conflict between what TfW want and need to increase services, but what NR are funded by DfT and able to deliver. If TfW owned the Penarth branch line it would be much more straightforward.

 

[MikePJ]

Maybe I've misremembered or been misinformed but I thought the original plan was for 2 trains per hour from Coryton to Penarth and another 2 trains per hour to Radyr via the City Line. Which I presume would need Cardiff West junction sorting out as well as a loop on the Coryton Line.

Yes, that chimes with my recollections too. There was cash specifically allocated to Cardiff West Junction in the Spending Review so that does seem likely.

 

[positron]

6tph to Penarth is currently impossible as it's a single track line, and there are no firm, committed plans to install either a passing loop (originally planned from Dingle Rd to Penarth, but now dropped) or another platform at Penarth.
It's the conflict between what TfW want and need to increase services, but what NR are funded by DfT and able to deliver. If TfW owned the Penarth branch line it would be much more straightforward.

There's a lot of documents and FOI responses that reference the Penarth line loop and second platform dating as far back as 2020, it would be odd if it didn't end up happening.

Having said that doing the loop round to Radyr could make sense instead (though idk if there's enough capacity to do that as well as avoid reversing the treherberts at Central?). Would that be 2x 756s and 2x 398s operating to Coryton then, or would they use 756s for the city line services too?

 

[AdamWW]

Having said that doing the loop round to Radyr could make sense instead (though idk if there's enough capacity to do that as well as avoid reversing the treherberts at Central?). Would that be 2x 756s and 2x 398s operating to Coryton then, or would they use 756s for the city line services too?

I believe the plan is for 3 car 756s on Coryton services and I don't think there are enough to do that.

The current service would use 5 of the 7 units.

While 4 trains per hour would be nice, it would be more useful for now if they had kept up their brief interest in trying to provide the current 2 trains per hour reliably.

 

[positron]

I'm assuming the 48m if it would fund a passing loop could fund a few extra units for the 4tph increase, and a passing loop + improved acceleration should fix many of the performance problems.

 

[MikePJ]

On Penarth - the most recent proposal (which has got as far as a planning consultation) was for an arrivals platform on a short loop at Penarth. That means it becomes possible to have two trains on the branch in the event of disruption, but doesn't allow the service to increase beyond 4tph (as iirc the branch is occupied for 12 minutes in every 15 at present).

For the possible Coryton-Radyr service I'd expect that to be operated by some extra 398s, as it would be simple for them to go to and from Taffs Well for maintenance. A 398 is likely cheaper than a 756, too!

 

[AdamWW]

a passing loop + improved acceleration should fix many of the performance problems.

I'm not sure that 4 trains per hour with loop is likely to be any more reliable than 2 trains per hour without, though it would mean one cancelled train would leave only a 30 minute rather than 60 minute gap.

It's not obvious to me that the improved acceleration will do more good than the increased dwell times and the threatened 20 mph limit over the level crossing between Whitchurch and Rhiwbina will do harm.