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In normal non-Covid times, LNER run services out of King's Cross at 00, 03, 06, 30 & 33 minutes past every hour
There is a big gap in departures in the second half of the hour, is there also a fast path available at 36 that they or nobody else is just not choosing to use at the moment?
Secondly, Grand Central and Hull Trains depart at either 27, 48 or 57 depending on the hour. Are these three fast paths also available every hour, and indeed is there also an hourly path at 18 mins past (which LNER use at 1718/1818) or does something else get in the way at this time?
There is a big gap in departures in the second half of the hour, is there also a fast path available at 36 that they or nobody else is just not choosing to use at the moment?
06 and 33 stop at Stevenage so 36 doesn't work with the Kings Lynn close behind.
In theory, you might be able to make the 00 (fast), 03 (Peterborough), 06 (Stevenage) pattern the same at 30, 33, 36 if it made sense to run the 30 fast to Grantham or Newark but Peterborough is more of a traffic generator for travel further north that you want North East departures from Kings Cross at 00 and 30 with one stopping at Peterborough, Leeds at 03 and 33 with one stopping at Peterborough and the other at Stevenage and York / Lincoln at 06 stopping at Stevenage. Clearly, there would be issues further north if this changed.
Also don’t forget there are only two tracks over Welwyn viaduct so any service going over there whether fast/slow passenger or freight occupies a path.
Whilst there may be spare fast line paths leaving King’s Cross those don’t mean there’s a path all the way north, not much use for an intercity train if you can’t get north of Welwyn. Track occupation over the viaduct is pretty high.
So, firstly we have to think about paths north from Kings Cross as including every train passing Alexandra Palace to Finsbury Park. This includes Thameslink through the core and GN from Kings Cross and from Moorgate.
Next let's think of constraints. Anything coming off the Moorgate doesn't occupy any constraints northbound, now that the new Stevenage platform is built. We can discount these.
EDIT: see posts 10, 11 & 13 below for exact reasoning why these trains can be discounted.
However, anything running main line past Welwyn Garden City northbound has to cross the two track section at Digswell. A fast train will take approximately a minute to clear this on greens. A train that has come off the slows, crosses this section and then rejoins the slows will take approximately three minutes. That three minutes is equivalent to one path out of Kings Cross, so for every train that does this, that's one fast path gone.*
Now, paths themselves.
Thameslink has 2tph semi-fast from Kings Cross to Cambridge. These go slow line and depart at xx.22 and xx.52, but cross the two track section at Digswell at xx.02 and xx.32. A fast train takes 17 minutes to reach this section, so that's the paths at xx.15 and xx.45 gone.
The four Thameslink trains out of the core run fast line as far as Hitchin/Stevenage. The Brighton to Cambridge trains occupy the equivalent of xx.09 and xx.39 paths. As JonathanH pointed out, the xx.06 and xx.36 paths are occupied by LNER stops at Stevenage, so those don't exist. The Peterborough to Horsham trains also run fast as far as Stevenage. These occupy the xx.21 and xx.51 paths.
The last ones are the Cambridge Fliers, occupying the fast lines non stop as far at Hitchin. These occupy the xx.12 and xx.42 paths.
So we have, theoretically a path every 3 minutes leaving Kings Cross, but as we've seen, not all of these are practical as a lot of them are used by TL and GN.
*It's actually a little more for trains that call at Welwyn North, but we can ignore that rounding error.
== Doublepost prevention - post automatically merged: ==
PART 2 - ECML capacity constraints
So, as outlined above, a lot of the paths are used, they're just not used by trains at LNER.
Thameslink use six paths per hour, four fast and two on the slows that stop at Welwyn North. LNER use five, although this changes in some hours, and itself will grow to six after Werrington/Kings Cross Remodelling (Dec 2022 timetable change). Great Northern use two for the Cambridge fliers. The OA operators use 1 between them on average. Add in two for resilience and you only get 16.
But a train can leave every three minutes. Add that up and that's 20 paths per hour? We're missing four.
Obviously this sometimes doesn't work out, because trains turn off at Hitchin or terminate at Peterborough, and therefore those paths aren't used beyond there, but in practice, these paths are used up further along the route.
1. The flat crossing at Newark uses 1 or 2 paths per crossing move, and there are two paths per hour, in each direction. Sometimes these can be parallel, but that doesn't always work out.
2. Freight trains using up 2 Northbound paths and 1 Southbound path while crossing over at Werrington Jn. Obviously this is being fixed, but it was for a while the major capacity constraint on the ECML. There are two freight paths northbound per hour.
Equally, southbound freight trains from Sleaford have to cross the northbound ECML as well, although they usually hold them outside Peterborough to wait for a quiet time to cross. This again uses another northbound path, but can be parallel with northbound freight.
Passenger trains from Sleaford now use the reversible slow line, and terminate at Peterborough, not using capacity.
3. East Midlands Railway run a train in each direction every hour (at 90mph Vs 125mph) from Peterborough to Grantham. This uses some paths.
4. There's a lot of freight on the ECML, and that's all max 75mph. It takes a long time to accelerate, decelerate or loop a 375m freight train, and that's a lot of paths. Granted, a lot of it gets diverted off, but what's there still has to travel across the same two track sections as the passenger trains.
5. Platform capacity at Kings Cross was lacking. Additionally, every fast train calling at Grantham or Newark or Durham among others eats a path, because you're stopping a train on a two track railway, and therefore stopping all trains behind it.
All paths south of Leeds are used up, at least as far as Wakefield and the flat junctions towards Sheffield. No more trains can be run to Leeds without impacting services there. The same applies for services to Newcastle, where the two track section to Darlington and the flat junction at Northallerton eats up capacity.
6. This brings us to our final issue, there's nowhere to send them. Anywhere worthwhile hasn't got the capacity, there wasn't a need for Lincoln to have an hourly service, and no real desire to terminate more trains at York. There weren't the spare trains, the slack in the timetable wasn't there, and noone really needed to. Indeed it was only really a decade ago that the desire to get new paths was set forth, and schemes such as King's Cross remodelling and Werrington will help realise these new paths.
***
There are a lot more complex reasons, and I haven't really fine into too much depth about the actual pathing out of Kings Cross, but I hope this gives an overview of the complexity of planning for more trains along such a busy and complex route. I apologise of it's a bit hard to follow, but I would add though, that the WCML is much, much worse.
So how does the ORR approved 8 tph long distance high speed timetable fit in, that we’ve been discussing for a few years? 6.5 tph ECML operator and 1.5 tph open access, isn’t it?
So how does the ORR approved 8 tph long distance high speed timetable fit in, that we’ve been discussing for a few years? 6.5 tph ECML operator and 1.5 tph open access, isn’t it?
Once the flyunder for freight trains to and from the Slow/Stamford lines North of Peterborough, to the Spalding/Sleaford lines at Werrington Junction is opened to traffic, this will free up capacity to allow for 8 Long Distance High Speed paths per hour.
Welwyn (Digswell) viaduct would still be a constraint, but even there, there has been a small improvement of replacing banner repeaters with three-state banners (that show green if the signal they are associated with is green). It's a small improvement, but will save important seconds there.
Once the flyunder for freight trains to and from the Slow/Stamford lines North of Peterborough, to the Spalding/Sleaford lines at Werrington Junction is opened to traffic, this will free up capacity to allow for 8 Long Distance High Speed paths per hour.
But unfortunately its not helping constraints, discussed elsewhere, north of York. I think north of Newcastle needs upto five Intercity paths in some hours.
So, firstly we have to think about paths north from Kings Cross as including every train passing Alexandra Palace to Finsbury Park. This includes Thameslink through the core and GN from Kings Cross and from Moorgate.
Next let's think of constraints. Anything coming off the Moorgate line goes via Hertford North, and therefore doesn't occupy any constraints northbound, now that the new Stevenage platform is built. We can discount these.
However, anything running main line past Welwyn Garden City northbound has to cross the two track section at Digswell. A fast train will take approximately a minute to clear this on greens. A train that has come off the slows, crosses this section and then rejoins the slows will take approximately three minutes. That three minutes is equivalent to one path out of Kings Cross, so for every train that does this, that's one fast path gone.*
Now, paths themselves.
Thameslink has 2tph semi-fast from Kings Cross to Cambridge. These go slow line and depart at xx.22 and xx.52, but cross the two track section at Digswell at xx.02 and xx.32. A fast train takes 17 minutes to reach this section, so that's the paths at xx.15 and xx.45 gone.
The four Thameslink trains out of the core run fast line as far as Hitchin/Stevenage. The Brighton to Cambridge trains occupy the equivalent of xx.09 and xx.39 paths. As JonathanH pointed out, the xx.06 and xx.36 paths stop at Stevenage, so those don't exist. The Peterborough to Horsham trains also run fast as far as Stevenage. These occupy the xx.21 and xx.51 paths.
The last ones are the Cambridge Fliers, occupying the fast lines non stop as far at Hitchin. These occupy the xx.12 and xx.42 paths.
So we have, theoretically a path every 3 minutes leaving Kings Cross, but as we've seen, not all of these are practical as a lot of them are used by TL and GN.
*It's actually a little more for trains that call at Welwyn North, but we can ignore that rounding error.
== Doublepost prevention - post automatically merged: ==
PART 2 - ECML capacity constraints
So, as outlined above, a lot of the paths are used, they're just not used by trains at LNER.
Thameslink use six paths per hour, four fast and two on the slows that stop at Welwyn North. LNER use five, although this changes in some hours, and itself will grow to six after Werrington/Kings Cross Remodelling (Dec 2022 timetable change). Great Northern use two for the Cambridge fliers. The OA operators use 1 between them on average. Add in two for resilience and you only get 16.
But a train can leave every three minutes. Add that up and that's 20 paths per hour? We're missing four.
Obviously this sometimes doesn't work out, because trains turn off at Hitchin or terminate at Peterborough, and therefore those paths aren't used beyond there, but in practice, these paths are used up further along the route.
1. The flat crossing at Newark uses 1 or 2 paths per crossing move, and there are two paths per hour, in each direction. Sometimes these can be parallel, but that doesn't always work out.
2. Freight trains using up 2 Northbound paths and 1 Southbound path while crossing over at Werrington Jn. Obviously this is being fixed, but it was for a while the major capacity constraint on the ECML. There are two freight paths northbound per hour.
Equally, southbound freight trains from Sleaford have to cross the northbound ECML as well, although they usually hold them outside Peterborough to wait for a quiet time to cross. This again uses another northbound path, but can be parallel with northbound freight.
Passenger trains from Sleaford now use the reversible slow line, and terminate at Peterborough, not using capacity.
3. East Midlands Railway run a train in each direction every hour (at 90mph Vs 125mph) from Peterborough to Grantham. This uses some paths.
4. There's a lot of freight on the ECML, and that's all max 75mph. It takes a long time to accelerate, decelerate or loop a 375m freight train, and that's a lot of paths. Granted, a lot of it gets diverted off, but what's there still has to travel across the same two track sections as the passenger trains.
5. Platform capacity at Kings Cross was lacking. Additionally, every fast train calling at Grantham or Newark or Durham among others eats a path, because you're stopping a train on a two track railway, and therefore stopping all trains behind it.
All paths south of Leeds are used up, at least as far as Wakefield and the flat junctions towards Sheffield. No more trains can be run to Leeds without impacting services there. The same applies for services to Newcastle, where the two track section to Darlington and the flat junction at Northallerton eats up capacity.
6. This brings us to our final issue, there's nowhere to send them. Anywhere worthwhile hasn't got the capacity, there wasn't a need for Lincoln to have an hourly service, and no real desire to terminate more trains at York. There weren't the spare trains, the slack in the timetable wasn't there, and noone really needed to. Indeed it was only really a decade ago that the desire to get new paths was set forth, and schemes such as King's Cross remodelling and Werrington will help realise these new paths.
***
There are a lot more complex reasons, and I haven't really fine into too much depth about the actual pathing out of Kings Cross, but I hope this gives an overview of the complexity of planning for more trains along such a busy and complex route. I apologise of it's a bit hard to follow, but I would add though, that the WCML is much, much worse.
So how does the ORR approved 8 tph long distance high speed timetable fit in, that we’ve been discussing for a few years? 6.5 tph ECML operator and 1.5 tph open access, isn’t it?
Let’s just say the ORR’s got a history of approving or specifying a greater number of paths than can reasonably be accommodated, see the TPE North farce of a couple of years ago. As an ex-Leeds planner we knew when it went to 5 TPH that 6 would need a timetable that was neither fit for purpose or reliable (or more track), but that was pre-MK when people who stated you couldn’t fit a quart into a pint pot were listened to rather than shunted aside.
Yes, but as established above, this is about fast paths out of Kings Cross.
The Hertford North terminators are irrelevant, they terminate off the main line.
The Welwyn terminators are irrelevant, they run slow line into the bay platform, and cross over the flyover to head south, and therefore don't take any fast paths. They also don't cross the main running lines on the flat.
The Stevenage terminators don't run up the main line, instead up the loop. At Stevenage, thanks to the new platform, they don't impact any main line services (nor any slow line services) as they are completely segregated.
The Moorgate services are therefore irrelevant to fast paths out of Kings Cross, or indeed any paths further than Welwyn Garden City.
Some great posts here, I wasn’t expecting such detailed answers.
In my initial question I assumed everything repeated every half an hour, so that’s why I questioned if there were any paths in the opposite half hour. I hadn’t factored in the LNER Stevenage calls aren’t evenly distributed
Constraints on the ECML
London King's Cross(to be solved this year as part of the East Coast Upgrade)
Digswell Viaduct
Welwyn North Station
Welwyn Tunnels
River Nene Viaduct
Werrington(to be solved this year as part of the East Coast Upgrade)
Newark flat crossing
Constraints on the ECML
London King's Cross(to be solved this year as part of the East Coast Upgrade)
Digswell Viaduct
Welwyn North Station
Welwyn Tunnels
River Nene Viaduct
Werrington(to be solved this year as part of the East Coast Upgrade)
Newark flat crossing
Constraints on the ECML
London King's Cross(to be solved this year as part of the East Coast Upgrade)
Digswell Viaduct
Welwyn North Station
Welwyn Tunnels
River Nene Viaduct
Werrington(to be solved this year as part of the East Coast Upgrade)
Newark flat crossing
Two track section Stoke Tunnel - Doncaster
Doncaster itself
Power supply north of Newcastle
Stopping patterns of different services north of Newcastle
Interaction between Services that swap Fast to Slow Line South of Hitchin (which is why the Moorgate services do matter in this analysis.)
There is a possibly a slight relevance, since they share the slow lines with the Kings Cross - Cambridge stopping services and these have to join the fast line to cross the Welwyn / Digswell Viaduct.
There is a possibly a slight relevance, since they share the slow lines with the Kings Cross - Cambridge stopping services and these have to join the fast line to cross the Welwyn / Digswell Viaduct.
This is true, although there are only two of each per hour in each direction, with the same stopping patterns. So the maximum a train can be delayed by in the down direction is three minutes. I'll explain.
If the two trains arrived simultaneously at Finsbury Park (unlikely as there is currently a 12/18 minute gap in the timetable) one train will have to wait a maximum of three minutes (one path) before it can follow the other up the slow line.
We now have a train on time, and a late train three minutes later. If the Cambridge slow is on time, nothing changes, and the Welwyn terminator simply arrives late and turns around in the bay.
If the Cambridge slow is late, it has the same stopping pattern and follows up three minutes late as far as Welwyn. It would have occupied the xx.15 or xx.45 path, but now running three minutes late, it occupies the next path. From my post above, these paths are unused, and it shouldn't delay anything that would be running right behind it.*
By the time the slow arrives at Stevenage, it's back off the fasts and onto the slows, and doesn't hold anything else up as it goes over the flyover to Cambridge.
Obviously, in extreme delays such as a train failing on the slows, or god forbid on the two track section, there will be major delays, but this is really rare. In those circumstances, the timetable falls down, but that's the same with any busy two track railway in the world.
*The next train timetabled over this section after the Cambridge slows is the Thameslink to Peterborough, which also calls at Stevenage anyway.
**NOTE: This is not the same as importing delays from Thameslink or south of the river. That is very possible and does happen on an alarmingly regular basis, which is why there isn't anything scheduled in the path behind the Thameslink stopper. This is merely about the interaction between the Moorgate terminators and the Thameslink slows, and why the Moorgate timetable can basically be considered separate from the ECML timetable beyond Welwyn Garden City.
EMR usually seem to be pathed out of the way on the Slows, so the difference only matters the relatively short distance between Grantham and Stoke Tunnel (where the slow turnout into Platform 4 and associated braking / acceleration on the main line make more of a difference than top speed)
