Lack of train crew on Great Northern?

[MikeWM]

Tonight seems to be an example of the Letchworth terminators causing some delay - 1L48 seems to have arrived at Letchworth 1.5 minutes late and then blocked the platform at Letchworth for 7 minutes (rather than the 4 minutes timetabled) which has turned a 1-minute delay on 1T50 (the 1739 off Kings Cross to Kings Lynn) into a 6-minute delay. Not massive in the scheme of things but it adds up.

 

[bramling]

Tonight seems to be an example of the Letchworth terminators causing some delay - 1L48 seems to have arrived at Letchworth 1.5 minutes late and then blocked the platform at Letchworth for 7 minutes (rather than the 4 minutes timetabled) which has turned a 1-minute delay on 1T50 (the 1739 off Kings Cross to Kings Lynn) into a 6-minute delay. Not massive in the scheme of things but it adds up.

It all points to GTR just not managing the basics. If it’s taking 7 mins to detrain an 8-car train at commuter time then something’s amiss.

I’m not really surprised though. It was always obvious this was what was going to happen, the complacency seen on here and elsewhere told its own story.

We do/did have 9J/9S/2C trips with no less than 3 to 4 different drivers!

That rather sums things up. Things just aren’t going to hold up well with crewing like this.

It’s quite apparent GTR seem to have absolutely no idea where crews are during disruption, hence why we see essentially the entire service disappearing into thin air for many hours.

 

[sharpener]

I'm quite sure the drivers have paperwork which tells them what times they are meant to arrive and depart stations they are stopping at.

Was asking about timing at waypoints where two tracks converge and the ideal outcome is to keep the headway to the minimum allowable, and whether the signallers provide additional information about where slow train A is in relation to overtaking train B before the start of the 2-track section.

Or does the driver just have a gut feel that if he is overtaken at say Knebworth he can maintain xx mph and the signal will clear before he has to brake for it.

How are you aware of when the signal cleared?ab

I think they are the light-on-stick things you can see through the train windows?

 

[WeGoAgain]

Was asking about timing at waypoints where two tracks converge and the ideal outcome is to keep the headway to the minimum allowable, and whether the signallers provide additional information about where slow train A is in relation to overtaking train B before the start of the 2-track section.

Or does the driver just have a gut feel that if he is overtaken at say Knebworth he can maintain xx mph and the signal will clear before he has to brake for it.

No, no way points. (I know there are in Aviation). - Signallers rarely speak to drivers and tend to do so only if there is a change of circumstances.

Driver will not necessarily know what the situation is. Using Knebworth approaching Woolmer Green Junction as in your example; a Train might be out of sync. Thus waiting for a fast one to go through on the Fast wouldn't necessarily mean the one on the Slow is next, even though it might have gone next 'yesterday'.
That said, if when approaching the signal it is displaying a Single Yellow, yes it can be timed, and if it's timed incorrectly, no great shakes as the next Signal is a fair distance away so they wouldn't need to brake aggressively to stop at it if needed.

I think they are the light-on-stick things you can see through the train windows?

I'd be surprised if you could see the signal change out of the Window from the Coaches/Carriages... Maybe you were up the front...

I have been on an up stopper where he coasted towards the 2-track stretch at Digswell, then as soon as overtaken by something doing line speed accelerated with great precision so had a good flying start just as the signal cleared.

Not sure what you mean by signal cleared. If you mean that the signal was showing a Red aspect, then cleared as the Train was very close to it, well, let's just say, one day it'll be Tea with no Biscuits for that Driver. But as I said, I highly doubt that could be seen from anywhere behind the Cab.

 

[Magdalia]

We do/did have 9J/9S/2C trips with no less than 3 to 4 different drivers!

Kings Cross-Cambridge stopping trains with three different drivers is nothing new, it has existed ever since electrification. Crew changes at Hitchin and Finsbury Park are consequences of having a traincrew depot at Hitchin and carriage sidings at Hornsey. Where does a third crew change happen to get four drivers?

Was asking about timing at waypoints where two tracks converge and the ideal outcome is to keep the headway to the minimum allowable, and whether the signallers provide additional information about where slow train A is in relation to overtaking train B before the start of the 2-track section.

Or does the driver just have a gut feel that if he is overtaken at say Knebworth he can maintain xx mph and the signal will clear before he has to brake for it.



I think they are the light-on-stick things you can see through the train windows?

One important point to remember is that, while we still have signals with lights on a stick, a driver on the up slow can also see the signals on the up fast.

In my long experience, it takes minimum about 1½ minutes from a standing start at Knebworth to the 2 track section. In that time any train that overtook in Knebworth station at line speed is going to be approaching Welwyn North, and the road will have cleared if nothing else is following. On the other hand, if another train is following on the up fast, then the road will clear on the up fast, and the driver of the stopper will be able to see that too.

 

[sharpener]

Not sure what you mean by signal cleared. If you mean that the signal was showing a Red aspect, then cleared as the Train was very close to it, well, let's just say, one day it'll be Tea with no Biscuits for that Driver. But as I said, I highly doubt that could be seen from anywhere behind the Cab.

I'd be surprised if you could see the signal change out of the Window from the Coaches/Carriages... Maybe you were up the front...

No but you can readily sense when the driver re-applies power. If over the xformer it all hums like billy-o, especially on the oldest stock where the 25kV came down a pipe between the seating.

Distance from that point to when you pass the signal then tells you how close you were and whether biscuits or not.

When I commuted into London regularly it was before the days of RTT so just posterior and Mark 1 human eyeball.

In my long experience, it takes minimum about 1½ minutes from a standing start at Knebworth to the 2 track section.

Was thinking more of a flying start scenario. Yes from a stop at Knebworth it will be long gone so a clear road if it is your turn next.

One important point to remember is that, while we still have signals with lights on a stick, a driver on the up slow can also see the signals on the up fast.

I didn't think of that. In the absence of a master plan or any more detailed info from signallers this may well be the key to it. So will it actually get more difficult with in-cab signalling? Supposing we are going to get that earlier than 4 tracks all the way.

 

[whoosh]

Kings Cross-Cambridge stopping trains with three different drivers is nothing new, it has existed ever since electrification. Crew changes at Hitchin and Finsbury Park are consequences of having a traincrew depot at Hitchin and carriage sidings at Hornsey. Where does a third crew change happen to get four drivers?

Welwyn Garden City has a traincrew depot.

 

[Magdalia]

I didn't think of that. In the absence of a master plan or any more detailed info from signallers this may well be the key to it. So will it actually get more difficult with in-cab signalling?

This discussion has made me wonder about that.

Welwyn Garden City has a traincrew depot.

But do they have any turns on the Kings Cross-Cambridge trains? My understanding is that the Welwyn traincrew depot is for the Moorgate inner suburban and the Thameslink Sevenoaks trains.

 

[whoosh]

But do they have any turns on the Kings Cross-Cambridge trains? My understanding is that the Welwyn traincrew depot is for the Moorgate inner suburban and the Thameslink Sevenoaks trains.

They do sign to Cambridge yes. They only go on 700s though as they don't sign 387s, but have got work on 1T's, 9S's, and 2C's.

There are two links (rotas), both sign Moorgate and Cambridge and one signs Sevenoaks in addition. In fact, one duty that is in the Sevenoaks link, goes to Sevenoaks, back to Finsbury Park, a 9S to Cambridge and back to Finsbury Park, finishing off with a 717 to Welwyn.

 

[Magdalia]

They do sign to Cambridge yes. They only go on 700s though as they don't sign 387s, but have got work on 1T's, 9S's, and 2C's.

There are two links (rotas), both sign Moorgate and Cambridge and one signs Sevenoaks in addition. In fact, one duty that is in the Sevenoaks link, goes to Sevenoaks, back to Finsbury Park, a 9S to Cambridge and back to Finsbury Park, finishing off with a 717 to Welwyn.

Thanks, that is an extra complication!

 

[Failed Unit]

I do often see them changing drivers at WGC on the London - Cambridge services. The traincrew are also "mushrooms" like the passengers. I was speaking to a driver once who was booked to work a Sevenoaks service but it was cancelled because of a set failure. He was trying to get to Finsbury Park to continue his duty. During disruption he was sure if he should get a train heading to Kings Cross, Moorgate or the following Sevenoaks service. No inside info for train crew He just had to take the gamble that if he got the Kings Cross it would get out ahead of the Moorgate or the rest of his diagram would be delayed as well.

 

[Bikeman78]

Complete meltdown on the GN side again tonight due to a trespass incident at Stevenage. Whatever the reasons, it isn’t really acceptable to have the whole GN service pretty much vanish into thin air for fairly run-of-the-mill problems.

The rolling stock diagrams seem fairly robust, but it seems the crew diagrams really aren’t. It’s the only real explanation for how the service just can’t recover from disruption.

I think that applies across the network now. Can anyone explain why? There was a time when a Swansea crew would work to Paddington, have a break, and work a train back to Swansea. The reverse applied for London crews. Now, we have crew relief at Swindon, or even Reading I think. How is this better? It makes service recovery impossible. I'm struggling to imagine how having people doing lots of small chunks of work is more efficient than two big chunks. I'm fairly sure that Swansea do still go to Paddington, so it's not as if they are cutting down on route learning.

They do sign to Cambridge yes. They only go on 700s though as they don't sign 387s, but have got work on 1T's, 9S's, and 2C's.

There are two links (rotas), both sign Moorgate and Cambridge and one signs Sevenoaks in addition. In fact, one duty that is in the Sevenoaks link, goes to Sevenoaks, back to Finsbury Park, a 9S to Cambridge and back to Finsbury Park, finishing off with a 717 to Welwyn.

Reading this, it is easy to see why the chaos on Thameslink quickly spreads.

 

[Steve Harris]

I think that applies across the network now. Can anyone explain why? There was a time when a Swansea crew would work to Paddington, have a break, and work a train back to Swansea. The reverse applied for London crews. Now, we have crew relief at Swindon, or even Reading I think. How is this better? It makes service recovery impossible. I'm struggling to imagine how having people doing lots of small chunks of work is more efficient than two big chunks. I'm fairly sure that Swansea do still go to Paddington, so it's not as if they are cutting down on route learning.

I can't explain why, but, back in BR days there used to be multiple crew changes on routes. When I was a lad (40 years ago) I used to travel to Peterborough from Cambridge on a Cam- Birmingham New Street service and the Cambridge drivers used to only know the route as far as Peterborough (so the 1st Crew change was at PBO, i believethere used to be a second but can't remember where). So multiple crew changes is nothing new, but unlike BR days there isn't the same number of spare drivers sitting idle nowadays ready to be used when there's disruption or someone calls in sick

 

[Bald Rick]

I didn't think of that. In the absence of a master plan or any more detailed info from signallers this may well be the key to it. So will it actually get more difficult with in-cab signalling? Supposing we are going to get that earlier than 4 tracks all the way.

The in cab signalling is already there and in service. It’s just that not all of the cabs are fitted, and few of the non- GTR drivers are trained. But, you can see the (positive) impact it will have already. If you look at the map for Welwyn viaduct on Open Train Times (see below), you can see extra ‘berths’ without signals - these are additional short sections for ETCS.

In the example you can see below, train 2C63 is on approach to 2152 signal. With conventional sigalling, any following train must be held at one of 2182 / 2180 signals in rear until 2C63 has cleared the overlap of 2152.

With ETCS, a following train being held at 2180 or 2182 would get a movement authority to proceed as soon as 2C63 has passed the overlap of the next section, which in both signals’ cases is actually still on the 4 track section, albeit the overlap will almost certainly be just on the two track. This means the second train can start moving well before the first train has entered Welwyn North tunnel, saving around 25 seconds if the first train is through at speed, more if the firsttrain is also startign from restricted aspects. And, also, rather than the second train starting off against a single yellow, and then proceeding round the corner slowly, expecting a red, the driver will receive progressively more movement authorities as the first train speeds through the section; he/she will therefore be able to accelerate to speed earlier, and clear the section more quickly for following trains.

This is going to be a significant help during any out of course running. It may even help squeeze an extra path out, if that can be used elsewhere.

 

[sharpener]

Thanks @Bald Rick et al. So no information about what is on the fast but much better granularity of own line, sounds a clear net benefit.

On a related line of thought, when approaching crossovers from slow to fast and vv (of which there are a great many between Hitchin and KGX), do the drivers (a) know in advance what the plan is (b) get route indication of some kind (can't remember many places where there are feathers) (c) deduce it from e.g. cautionary aspects or (d) get taken by surprise?

 

[bramling]

Kings Cross-Cambridge stopping trains with three different drivers is nothing new, it has existed ever since electrification. Crew changes at Hitchin and Finsbury Park are consequences of having a traincrew depot at Hitchin and carriage sidings at Hornsey.

There’s a lot more crew changes now on the stopping trains than in FCC / WAGN days. I don’t remember crew changes happening regularly at Finsbury Park and Welwyn Garden City, and neither at Hitchin to the extent that they do now.

This may be partly a consequence of the off-peak turning at Letchworth, but if you’re going to have then then it makes more sense for it to be on the down journey not the up.

As for Finsbury Park (and probably Welwyn) this ideally shouldn’t be happening at all. It’s just too fragile during disruption.

It’s bordering on lunacy to have a train which leaves King’s Cross and then has a driver change within 5 minutes.

 

[Twotwo]

Thanks @Bald Rick et al. So no information about what is on the fast but much better granularity of own line, sounds a clear net benefit.

On a related line of thought, when approaching crossovers from slow to fast and vv (of which there are a great many between Hitchin and KGX), do the drivers (a) know in advance what the plan is (b) get route indication of some kind (can't remember many places where there are feathers) (c) deduce it from e.g. cautionary aspects or (d) get taken by surprise?

Mashmoor you can go from up slow to up fast and you don't get checked down because the up slow speed is 75 and the points are set as 70 (meaning you can brake at the signal)

Potters bar is 30/40 depending if going from up fast to up slow and VV

New barnet is 25 in either directions

New southgate can go from up fast to up slow 40 mph

Next would be up fast to slow at finsbury park 30

 

[swing]

As for Finsbury Park (and probably Welwyn) this ideally shouldn’t be happening at all. It’s just too fragile during disruption.

It’s bordering on lunacy to have a train which leaves King’s Cross and then has a driver change within 5 minutes.

I thought the only driver changes at Finsbury Park were from trains coming from Brighton / Horsham etc. through the Thameslink Core and via St Pancras, rather than King's Cross (and vice versa, only for trains going South via St Pancras)

 

[Horizon22]

It all points to GTR just not managing the basics. If it’s taking 7 mins to detrain an 8-car train at commuter time then something’s amiss.

Need extra resource to detrain then or Letchworth has a staffing issue. I've seen longer trains (9-10 cars) regularly timetabled to be detrained in 3-4 minutes and never missed.

I think that applies across the network now. Can anyone explain why? There was a time when a Swansea crew would work to Paddington, have a break, and work a train back to Swansea. The reverse applied for London crews. Now, we have crew relief at Swindon, or even Reading I think. How is this better? It makes service recovery impossible. I'm struggling to imagine how having people doing lots of small chunks of work is more efficient than two big chunks. I'm fairly sure that Swansea do still go to Paddington, so it's not as if they are cutting down on route learning.

Swansea - London - PNB - London - Swansea was a daily Swansea diagram. Unless there were concerns about continuous driving time or lack of route variety, it seemed fairly robust.

A lot of the issues seem on Great Northern seem to do with poor (or at best, inefficient) crew resourcing / planning and control operations. Seems like it needs a "back to basics" review.

Kings Cross-Cambridge stopping trains with three different drivers is nothing new, it has existed ever since electrification. Crew changes at Hitchin and Finsbury Park are consequences of having a traincrew depot at Hitchin and carriage sidings at Hornsey.

It may do, but it's a sure-fire way to lead to disruption being prolonged and more widespread.

 

[Failed Unit]

I thought the only driver changes at Finsbury Park were from trains coming from Brighton / Horsham etc. through the Thameslink Core and via St Pancras, rather than King's Cross (and vice versa, only for trains going South via St Pancras)

The Moorgate services often change at Finsbury Park as well.

 

[bramling]

I thought the only driver changes at Finsbury Park were from trains coming from Brighton / Horsham etc. through the Thameslink Core and via St Pancras, rather than King's Cross (and vice versa, only for trains going South via St Pancras)

There’s definitely some crew changes at Finsbury Park for the stopping services as well. I’m not sure how many though.

Need extra resource to detrain then or Letchworth has a staffing issue. I've seen longer trains (9-10 cars) regularly timetabled to be detrained in 3-4 minutes and never missed.



Swansea - London - PNB - London - Swansea was a daily Swansea diagram. Unless there were concerns about continuous driving time or lack of route variety, it seemed fairly robust.

A lot of the issues seem on Great Northern seem to do with poor (or at best, inefficient) crew resourcing / planning and control operations. Seems like it needs a "back to basics"

On the latter point, definitely.

I witnessed another mess yesterday morning. 0454 Letchworth to King’s Cross. Delayed at Stevenage due to over-running engineering work. It was then announced the service would miss Welwyn GC and Hatfield. A few minutes later the signal cleared and the train departed straight away. Then came to a stand at the next signal (which was clear). Driver then announced train was being diverted via Hertford and this was the first he knew about it. To be fair the rest of the journey was fine, but it was still a somewhat late arrival.

But if the control function can’t effectively manage a relatively minor issue first thing in the morning, then it doesn’t bode well for larger incidents.

 

[Bald Rick]

On a related line of thought, when approaching crossovers from slow to fast and vv (of which there are a great many between Hitchin and KGX), do the drivers (a) know in advance what the plan is (b) get route indication of some kind (can't remember many places where there are feathers) (c) deduce it from e.g. cautionary aspects or (d) get taken by surprise?

Signalling principles require drivers to be notified of the route they are taking at the signal on approach to the junction, either by a route indicator (feathers) or other means, usually a ‘theatre’ or ‘stencil’ indicator that displays an Alpha-numeric line code. Unless the linespeed through the diverging route is different to the through route by 10mph or less, then trains will be given warning in advance through the signalling sysytem, either approach control (signals held at a restrictive aspect before the train arrives at the junction) or flashing yellows which will apply to only one diverging route if there are multiple diverging route options.

 

[MikeWM]

Tonight's problem seems to be due to 9S42 (1544 Brighton to Cambridge) losing 13 minutes somewhere around Purley.

That's made 2C46 Kings Cross->Cambridge 8 late at Hitchin, which has made 9J50 Horsham->Peterborough 5 late at Hitchin, which has made 1L48 also 5 late at Hitchin, which has then delayed 1T50 (until then on-time) by 8 minutes while it terminates and moves off at Letchworth - though again that moving off seems to have taken 7.5 minutes rather than the 4 timetabled, turning what would have been a 4 minute delay to 1T50 into 8 minutes.

I wonder if part of the problem is that there are just too many trains from too many origins that need to present at Hitchin in the right order and more-or-less on time; and if that doesn't happen for whatever resaon than 1L48 terminating at Letchworth is going to block 1T50 for some minutes. Combine that with the apparent inability to move 1L48 off Letchworth quickly, and maybe the problems here are starting to become clearer - this is twice this week that 1L48 has delayed 1T50 at Letchworth, and on two other days the service was a total mess.

 

[sharpener]

... a route indicator (feathers) or other means, usually a ‘theatre’ or ‘stencil’ indicator that displays an Alpha-numeric line code

Many thanks for your comprehensive answers. As a small boy I was fascinated by the feathers at New Malden where the Kingston branch goes off. More recently at Hitchin, though the flyover has made quite a difference (and a massive land take - pity they never built the burrowing junction). Must watch more carefully for the alphanumeric displays.

 

[bramling]

Tonight's problem seems to be due to 9S42 (1544 Brighton to Cambridge) losing 13 minutes somewhere around Purley.

That's made 2C46 Kings Cross->Cambridge 8 late at Hitchin, which has made 9J50 Horsham->Peterborough 5 late at Hitchin, which has made 1L48 also 5 late at Hitchin, which has then delayed 1T50 (until then on-time) by 8 minutes while it terminates and moves off at Letchworth - though again that moving off seems to have taken 7.5 minutes rather than the 4 timetabled, turning what would have been a 4 minute delay to 1T50 into 8 minutes.

I wonder if part of the problem is that there are just too many trains from too many origins that need to present at Hitchin in the right order and more-or-less on time; and if that doesn't happen for whatever resaon than 1L48 terminating at Letchworth is going to block 1T50 for some minutes. Combine that with the apparent inability to move 1L48 off Letchworth quickly, and maybe the problems here are starting to become clearer - this is twice this week that 1L48 has delayed 1T50 at Letchworth, and on two other days the service was a total mess.

I think the reality that is becoming very obvious is that there’s numerous pinch points. Hitchin is one for sure, but there’s numerous others. The single-line sections north of Littleport, Ely North Junction, Cambridge station area, the whole Hitchin to Cambridge section, Digswell-Woolmer Green, Welwyn Garden City station, the slow lines between Welwyn Garden City and Alexandra Palace, Alexandra Palace station, and of course Finsbury Park especially with the notorious crew reliefs that occur there.

The problem is that to make all that work, you essentially need as many trains as possible to be on time. GN has enough issues of its own, but the risk of trains not being on time is multiplied by the possibility of importing delays from south of the river. And, on top of that, frankly the Thameslink services aren’t resilient enough - there’s not enough turnround time at both Cambridge and Peterborough for a start, and probably not really enough space at those stations to allow Thameslink to turn robustly - look for example at the way Thameslink services alternate between platforms 1 and 7 at Cambridge.

GTR’s messy crew diagrams don’t help, but they’re just one part of a very dysfunctional picture.

Should we be surprised at any of this? Of course not. Remember we were told by someone rather on the inside of the Thameslink Programme that GN is “simple” and “like the Northern Line”. That says it all really.

 

[Class 170101]

and of course Finsbury Park especially with the notorious crew reliefs that occur there.

I find this odd to be honest as to why this is done. Do Horsham / Brighton (other Southern depot as appropriate) not sign the ECML north of Finsbury Park.

The problem is that to make all that work, you essentially need as many trains as possible to be on time. GN has enough issues of its own, but the risk of trains not being on time is multiplied by the possibility of importing delays from south of the river. And, on top of that, frankly the Thameslink services aren’t resilient enough - there’s not enough turnround time at both Cambridge and Peterborough for a start, and probably not really enough space at those stations to allow Thameslink to turn robustly -

I would have said Peterborough has sufficient turnaround (just under 20 minutes) and Brighton (over 20 minutes) but Horsham and Cambridge have tight turnarounds. The only way you will deal with this is by inserting an extra diagram in the circuit. This will cost more train crew and also the trains will need to be removed somewhere as they wait longer at Cambridge / Horsham.

look for example at the way Thameslink services alternate between platforms 1 and 7 at Cambridge.

Not really an issue caused by Thameslink, more inter-weaving around other operators and managing and maximising efficiency of platform working.

GTR’s messy crew diagrams don’t help, but they’re just one part of a very dysfunctional picture.

I'd be inclined to agree. Welwyn is a terminal point for Metro services (Moorgates) so crew changes there seem reasonable and does it not have a depot there too? Finsbury Park is not though and changing crew there on a regular basis seems a recipe for disaster. The diagrams really should be blocks of work on one route or on two different routes separated by a PNB. Not lots of chopping and changing if thats whats being described.

 

[mathstrains19]

I find this odd to be honest as to why this is done. Do Horsham / Brighton (other Southern depot as appropriate) not sign the ECML north of Finsbury Park.

I believe all drivers at both Peterborough and Horsham (as an example) sign the full route between them, but only 5 diagrams involve a full trip from Peterborough to Horsham/vice versa. I presume it is more efficient to have a driver do 2 Horsham-Finsbury Park returns during their shift, than doing a Horsham-Peterborough return and then not having time for another trip of any reasonable length (numbers are all examples, I don't know to what extent they fit with maximum shift lengths, but hopefully you get the idea)

 

[43096]

I think the reality that is becoming very obvious is that there’s numerous pinch points. Hitchin is one for sure, but there’s numerous others. The single-line sections north of Littleport, Ely North Junction, Cambridge station area, the whole Hitchin to Cambridge section, Digswell-Woolmer Green, Welwyn Garden City station, the slow lines between Welwyn Garden City and Alexandra Palace, Alexandra Palace station, and of course Finsbury Park especially with the notorious crew reliefs that occur there.

Presumably the logic behind the Finsbury Park crew changes is that there are more platforms so it's easier to work around any issues than doing the changes at, say, St. Pancras where the lack of a forward crew would completely stuff the entire Thameslink service up.

 

[GN Boy]

I believe all drivers at both Peterborough and Horsham (as an example) sign the full route between them, but only 5 diagrams involve a full trip from Peterborough to Horsham/vice versa. I presume it is more efficient to have a driver do 2 Horsham-Finsbury Park returns during their shift, than doing a Horsham-Peterborough return and then not having time for another trip of any reasonable length (numbers are all examples, I don't know to what extent they fit with maximum shift lengths, but hopefully you get the idea)

Plus, a lot of Peterborough and Cambridge services north of Finsbury Park are crewed by GN drivers that do not have the TL Core and beyond on their route cards.

 

[Failed Unit]

Presumably the logic behind the Finsbury Park crew changes is that there are more platforms so it's easier to work around any issues than doing the changes at, say, St. Pancras where the lack of a forward crew would completely stuff the entire Thameslink

service up.

With the tight timetable. This change often causes problems. The London - Cambridge is often heavily delayed if something goes wrong.