That’s interesting! Where are these rules set? What’s the reasoning behind them?
Definitely requires more platforms at Blackfriars, then. Would massively increase the cost of the project but oh well.
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Fantasy - Deconflicting services at Herne Hill
- Thread starter squingo44
- Start date
Definitely requires more platforms at Blackfriars, then. Would massively increase the cost of the project but oh well.
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RailUK Forums
Network Rail’s Train Planning rules, all in the public domain.
Agreed by the industry.
Reasoning behind them is, mostly, the laws of physics.
What’s the difference between national rail trains and Jubilee Line trains such that they can achieve the shorter turnaround times?
zwk500
Veteran Member
A mix of operational procedures and staffing arrangements.
The turnround time for both operators will be wheels stop to wheels start, and includes the doors being opened, 1st cab being secured, getting the driver into the 2nd cab, 2nd cab being set up, and then the despatch procedure. It can also include some element of recovery time to account for slightly late arrivals of the inward train.
There will be time savings in things like doors and cabs, but the big difference is that LU assume a 2nd driver is standing ready and waiting for the train to immediately get the 2nd cab set up ready for departure. Whereas Network Rail rules (generally) assume the same driver works the train back out, and therefore has to walk the length of the platform. The TPRs are published publicly on NR's website and you can see how many minutes each additional amount of carriages add to a turnround.
How does London Overground work? Which practice does it adopt?
zwk500
Veteran Member
Usually assumes the same driver works back but it has shorter trains.
Here's a quote from the rules directly.
Got it, thanks. So with 4 platforms at Blackfriars it would be possible to get 20 TPH.
Assuming that doesn’t happen - 10tph is still fine.
Remember that we have at least 4tph into the core (current Loop services) to consider first. I would think they go to Orpington / Sevenoaks / Swanley as stoppers (nothing much terminates at Stanley but surely it could?)
And the bays services are the faster ones out to Bromley South (all calling Elephant I guess - maybe Herne Hill if it is this super powered cross platform interchange) - and they cover the Maidstone services, and everything today through Rochester.
Which is only 4tph - but possibly Canterbury East route could go back to 2tph? I know HS1 killed it a bit and West triumphed. Or the TL Rainham becomes a Blackfriars - Bromley - Rainham 2tph in addition to the 2tph beyond Faversham. Speed the latter up a bit.
Remember that we have at least 4tph into the core (current Loop services) to consider first. I would think they go to Orpington / Sevenoaks / Swanley as stoppers (nothing much terminates at Stanley but surely it could?)
And the bays services are the faster ones out to Bromley South (all calling Elephant I guess - maybe Herne Hill if it is this super powered cross platform interchange) - and they cover the Maidstone services, and everything today through Rochester.
Which is only 4tph - but possibly Canterbury East route could go back to 2tph? I know HS1 killed it a bit and West triumphed. Or the TL Rainham becomes a Blackfriars - Bromley - Rainham 2tph in addition to the 2tph beyond Faversham. Speed the latter up a bit.
zwk500
Veteran Member
Correct. Longest time between trains of 11 minutes (12-car), so 5 tph in each platform with a minute to spare between each train.
Note that with 20tph you will also need to balance the margins. 20tph would require an arrival and departure every 3 minutes, and you will require 1 minute between a conflicting arrival and departure and 3 minutes between a conflicting departure and arrival. So for arrivals into platform 3 you'd require 4 minutes between departures and for departures from the theoretical platform 6 you'd require 4 minutes between arrivals.
This means that you will need to 'bunch' trains up on the line towards Loughborough junction, so at least two consecutive following movements would need a 2.5 minute headway (or 1 movement at a 2 minute headway).
All of this assumes that the layout is completely remodelled to provide all possible parallel moves. Not that there's any room to actually do that as the adjacent buildings are tight up to the existing line.
This is achievable for the current planning headways (2 minutes Blackfriars to Southwark Bridge Jn in both directions, just north of Elephant and Castle), but it will impose limits on your theoretical timetables.
You raise a good point. If there’s capacity on the Thameslink Core, those services could be used as well. I would consider it worthwhile to take over the Rainham TL service and the Catford loop TL service as well. We could have 8 TPH through the core and 8 TPH terminating at Blackfriars, along with 8 TPH to Orpington and 8 TPH to Swanley? Meaning 4 TPH for each origin-destination pair. If Swanley isn’t the best place to terminate, then extensions to Sevenoaks and Gillingham/Rainham are possible.
This amount of branching probably just about hits the limit of the timetable, but perhaps an 4 services could be fit in somehow by slotting in 2 more to the core and 2 more terminating at Blackfriars. And, of course, at this frequency all services will require an all stops stopping pattern unless we want to invest in a bunch of passing loops.
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Would relaxing to 16 TPH be more realistic then?
Unlikely, as junction margins on the approaches would need to be considered. 18tph is a more likely macimum, and that wouldn’t be particualrly robust.
zwk500
Veteran Member
16tph would at least prevent the need to 'bunch' trains (or grade separate), although if we're talking about being realistic I think you need to take a step back and look at what connectivity you are actually proposing at a regional level.
Well given that Herne Hill is currently limited to 16 TPH during peak times, getting 16 TPH Sutton-Victoria and 16 TPH Blackfriars-Bromley seems like a decent uplift.
zwk500
Veteran Member
And which connections are you *not* providing?
Well, the direct connection between the West Dulwich branch and Victoria station would be severed, but the service frequency increased so much that generalised journey times would be lower even accounting for an interchange at Herne Hill. And vice versa for Sutton Loop journeys to Blackfriars.
This will require the withdrawal of stopping services to the Catford Loop, or at least lowering them down to 2 TPH at peak hours, but the Bakerloo Line Extension to Hayes would again make up for that with better generalised journey times across the board through higher service frequencies.
And there’s still capacity on Victoria-Sutton section of the network to accommodate freight services to and from Streatham Hill.
Only by implication. But that then leads to the question of why you think that Sutton loop passengers would want to lose their service to the City - on a line that has always been biased to the City rather than West End.
I understand that there would be significant opposition, but this proposal avoids the cost of building grade separation at Herne Hill while providing a large enough increase in service frequency to give lower generalised journey times even with the interchange.
Maybe after the Windmill Junction rebuild, running some Thameslink services to Sutton via West Croydon would be feasible?
That doesn't answer my question about why. If there would be significant opposition, perhaps we ought to be considering who the trains would be for, and why passengers would benefit?
I'm also very suspicious of a case based on "generalised journey times" as my experience is that changing train is a significant degradation of service. And having (occasionally) used TL services from Wimbledon to City Thameslink, I'd certainly not be happy to go from probably having a seat throughout to probably having a seat till I change, and then definitely not.
The why is for a better service overall. A meaningful increase in service frequency outweighs the downsides of interchange, not least because of the additional capacity!
More than doubling the number of trains per hour on each of the lines through Herne Hill would bring service frequencies in line with London Overground services - with which passengers generally have no problem with interchanges.
You say you’re suspicious of arguments using generalised journey times, but then describe a complaint around not being able to find a seat on a train? What problem do you think increasing service frequencies aims to solve?
More than doubling the number of trains per hour on each of the lines through Herne Hill would bring service frequencies in line with London Overground services - with which passengers generally have no problem with interchanges.
You say you’re suspicious of arguments using generalised journey times, but then describe a complaint around not being able to find a seat on a train? What problem do you think increasing service frequencies aims to solve?
That’s fine, except that you’re introducing the change (including navigation of a subway) near the end of the journey, where both trains are likely to be heavily laden.
I thought the idea of splitting the Northern Line and forcing changes at Camden Town was brave, but this…
And that's the point - compelling that interchange by removing existing through services is highly disruptive. What is the interchange capacity at Herne Hill between the two island platforms? Can they even cope with crossing trainloads of passengers?
Your suggestion's been shown not to work due to the constraints of train operating; I don't think you've even considered the people who use those trains and what impact this will have on them in the real world.
And, in your determination to upgrade one outer suburban section, you've casually written off the existing flows on both the Catford Loop and the Chatham main line.
At a cost of:
Resignalling / remodelling Herne Hill
Rebuilding Herne Hill station to deal witha very significant increase in interchange passengers
Building new platfroms at Blackfriars (across the Thames, and demolishing several hundred million pounds worth of real estate to get tracks to them)
Building more platforms at Victoria (same applies)
Rebuilding Herne Hill station to accommodate that level of passenger flow would be fairly feasible, though, right? It wouldn’t require huge amounts of new track or anything.
And I absolutely am accounting for passenger flows along the Chatham main line and the Catford loop! Increased service frequencies would make services more accessible, not less. And while the loss of connectivity to the current destinations is a cost, it’s made up for by the benefit of the connectivity to the new destination. Wouldn’t you say there’s an equal argument to be made about the current poor connectivity of the interchange at Herne Hill due to low service frequencies?
Maybe extending Blackfriars could be avoided if those paths went into the Thameslink core instead. What additional platforms at Victoria do you consider to be necessary, when my proposal is to disconnect the Chatham Main Line from Victoria?
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Well that’s a little frustrating.
zwk500
Veteran Member
I think it would help us all, and yourself, if you could clearly either list or draw out the existing service patterns, and your proposed changes to them.
In part because I've been wanting to ask a question about how many additional trains this would require and where you're going to maintain them.
That’s fair. I’m changing the plans in my head as I respond to feedback.
In a nutshell, it would be 16 TPH Bromley-Blackfriars, with 8 terminating and 8 continuing on the Thameslink core (eliminating the TL services to Kent, via Catford, and Sutton), and with 8 continuing to Orpington and 8 continuing to Sevenoaks.
The Sutton Loop would be upgraded to support 16 TPH to Victoria, and the Catford Loop would take all fast services to Victoria from the Chatham Main Line.
Additional train depots would need to be built somewhere along the Sutton Loop and somewhere along the Chatham Main Line, maybe in Bromley.
Hmm. An extension of Victoria station would be necessary, in that case. Expanding Blackfriars station really would be useful here.
I don't know whether it would be feasible - but as you're proposing this idea, perhaps you've looked at it? It's a constricted site, with buildings close to the viaduct on both sides at Zone 2 values. And the rebuilding would be disruptive while it lasted.
You keep going on about this extra connectivity. On what basis do you assert that this expensive project is necessary and desirable? Passengers on the Sutton loop already have single interchange access to Victoria, but somehow you believe that this isn't good enough - yet want to impose changes for those travelling to the City (from SW London) or Victoria (from SE London) when the existing services provide the basis for precisely those journeys. You also appear to want to remove stopping services from the Catford Loop to generate these notional benefits, yet I can't see where the impact features in your modelling.
For modelling purposes, its obviously worth considering how usage patterns would vary, and calculating those as (No. of passengers * change in journey time), allowing for the impact of changes in frequency. But that needs some real world thought. Each one of those numbers is a real human being, who has choices about their journey. They will place a value on convenience, which won't just measurable in journey time. Just as a trivial example, when I've used Thameslink from Wimbledon it's been because it's been hassle reducing to go one stop on the District Line to Wimbledon, then change there and pick up a coffee for a train that will take me to less than 5 minutes walk from the office. Put the extra change in, and I'm straight to the Tube.
If the capacity needs boosting (and I'm not arguing against that), then perhaps the answer is to bite the bullet and build a flying junction at Herne Hill - it couldn't be much more more expensive or disruptive than what you are proposing.
I don't think this needs any new platforms at Victoria (eastern is a ghost town) or Blackfriars - if we're saying 10tph + at least 4 to core.
Herne Hill would need to stay as 8 car, but that's fine as so are the others. Blackfriars and Bromley South are 12, Elephant cannot. So it's likely an 8 car route. So good to twin with stoppers on the St Albans route.
Given the speed approaching Herne Hill from the north TL route, I would think it easier to have all trains call there. So that would give outer services a connection option into Victoria still. I am assuming there will still be Victoria - Denmark Hill - Bromley - XXX services in this scenario, and perhaps those could increase and serve places who lose their Victoria service here.
If this was a proper cross-platform set-up at Herne Hill, with TUAG frequency (8tph on each line) - then I think the platforms would cope. More benches and shelter. Entries/exits would be the problem. But if frequency is good enough, it'll be easy.
And for everyone who has a journey impacted with a change, new direct ones are created. Maybe the folks of e.g. West Dulwich or Kent House prefer a City journey, and Tulse Hill or Streatham to Victoria are probably big unserved flows.
Herne Hill would need to stay as 8 car, but that's fine as so are the others. Blackfriars and Bromley South are 12, Elephant cannot. So it's likely an 8 car route. So good to twin with stoppers on the St Albans route.
Given the speed approaching Herne Hill from the north TL route, I would think it easier to have all trains call there. So that would give outer services a connection option into Victoria still. I am assuming there will still be Victoria - Denmark Hill - Bromley - XXX services in this scenario, and perhaps those could increase and serve places who lose their Victoria service here.
If this was a proper cross-platform set-up at Herne Hill, with TUAG frequency (8tph on each line) - then I think the platforms would cope. More benches and shelter. Entries/exits would be the problem. But if frequency is good enough, it'll be easy.
And for everyone who has a journey impacted with a change, new direct ones are created. Maybe the folks of e.g. West Dulwich or Kent House prefer a City journey, and Tulse Hill or Streatham to Victoria are probably big unserved flows.