Thameslink Core Major Power Failure 28/8/25

[Hadders]

Apologies if there's a thread about this but I can't find one.

There was a major power failure in the Blackfriars area around 14:00 today, nothing has run through the core to the GN side since 14:30.

I was travelling from Finsbury Park to Stevenage around 22:00 this evening. I saw the detail of the disruption and thought it was better to head to Kings Cross which in the end proved to be wise decision. I was hoping some of the GN Thameslink services might have been diverted to KGX but this wasn't the case at the time I was there. Thankfully the Cambridge Express services had additional calls added at Finsbury Park, Stevenage and Hitchin so I boarded the late running 22:09 which was completely wedged, even right at the front of the train. I've rarely seen so many people get off a train at SVG but despite this the train left full and standing.

There didn't appear to be any trains operating to stations between Hitchin and Peterborough. Staff were trying to sort out aoternatives for passengers going towards Peterborough, they were doing a good job in the circumstances but looked stressed which given the circumstances is understandable.

Not a good day on the GN side. Does anyone know what happened?

 

[Magdalia]

Apologies if there's a thread about this but I can't find one.

It is here:

'Operational incident' affecting 1P88 18:12 King's Cross - Peterborough today? (28/08/2025)

Today, I travelled from Stevenage to Huntingdon and was planning on taking 1P88, which is the 18:35 from Stevenage to Huntingdon. This was until I found out the train forming 1P88 was 50 minutes late, so I bit the bullet and took 1P86, the 18:05 from Stevenage (I would've taken the 18:15 or 45...

www.railforums.co.uk

 

[Intercity_225]

Apologies if there's a thread about this but I can't find one.

There was a major power failure in the Blackfriars area around 14:00 today, nothing has run through the core to the GN side since 14:30.

I was travelling from Finsbury Park to Stevenage around 22:00 this evening. I saw the detail of the disruption and thought it was better to head to Kings Cross which in the end proved to be wise decision. I was hoping some of the GN Thameslink services might have been diverted to KGX but this wasn't the case at the time I was there. Thankfully the Cambridge Express services had additional calls added at Finsbury Park, Stevenage and Hitchin so I boarded the late running 22:09 which was completely wedged, even right at the front of the train. I've rarely seen so many people get off a train at SVG but despite this the train left full and standing.

There didn't appear to be any trains operating to stations between Hitchin and Peterborough. Staff were trying to sort out aoternatives for passengers going towards Peterborough, they were doing a good job in the circumstances but looked stressed which given the circumstances is understandable.

Not a good day on the GN side. Does anyone know what happened?

I was travelling from St Pancras - Stevenage and then Stevenage - Huntingdon and, having gotten off an Overground at Euston, walked towards St Pancras, went to the Thameslink area. I saw one ticket barrier open with a huge crowd of passengers around. The staff was saying things like 'Passengers for Gatwick go down!'.

When I got down to the platforms, the departure board showed every train was cancelled, and wasn't even showing Peterborough or Cambridge. We decided to quickly get to King's Cross and catch the 16.27 Cambridge from there. Once we got there, we asked the person at the information desk what to do, and he said quickly get to platform 0, so we got there and found a 700 heading to Peterborough, about half empty.


After getting to Stevenage, we saw no Thameslink services for the whole time we were there (except one which terminated there, reversed at Langley Jn and formed a Peterborough service.)

Certainly not a great day..

 

[Deepgreen]

It is here:

'Operational incident' affecting 1P88 18:12 King's Cross - Peterborough today? (28/08/2025)

Today, I travelled from Stevenage to Huntingdon and was planning on taking 1P88, which is the 18:35 from Stevenage to Huntingdon. This was until I found out the train forming 1P88 was 50 minutes late, so I bit the bullet and took 1P86, the 18:05 from Stevenage (I would've taken the 18:15 or 45...

www.railforums.co.uk

However, that thread doesn't even mention a power failure or any background to the problem.

 

[Russel]

For something that has seen so much money thrown at it, the Thameslink core seems somewhat fragile.

 

[andyjhatton]

For something that has seen so much money thrown at it, the Thameslink core seems somewhat fragile.

I suppose on the flip side, capacity wise it's pushed to the very limit.
I can't imagine there are many 2-track heavy-rail stations that have the service frequency that Thameslink core gets.

 

[Surreytraveller]

I suppose on the flip side, capacity wise it's pushed to the very limit.
I can't imagine there are many 2-track heavy-rail stations that have the service frequency that Thameslink core gets.

It's never reached the capacity it was designed for. It was originally designed for 24 trains an hour. It's never had that

 

[Supercoss]

700 135 half set became defective in platform 1at Blackfriars causing a circuit breaker to trip on the conductor rail section. Whilst this was sorted Bi Directional working via plat 2 , unit eventually moved under own power to naughty siding at 3 Bridges.

 

[Mattplans]

I suppose on the flip side, capacity wise it's pushed to the very limit.
I can't imagine there are many 2-track heavy-rail stations that have the service frequency that Thameslink core gets.

It's my understanding, actually, that GTR are not even running all of the services that were originally planned to operate through the core. is that what we now call "pushed to the very limit"?

 

[Hadders]

Does anyone know why nothing ran through the core onto the GN side for the rest of the day?

 

[galwhv69]

Apologies if there's a thread about this but I can't find one.

There was a major power failure in the Blackfriars area around 14:00 today, nothing has run through the core to the GN side since 14:30.

I was travelling from Finsbury Park to Stevenage around 22:00 this evening. I saw the detail of the disruption and thought it was better to head to Kings Cross which in the end proved to be wise decision. I was hoping some of the GN Thameslink services might have been diverted to KGX but this wasn't the case at the time I was there. Thankfully the Cambridge Express services had additional calls added at Finsbury Park, Stevenage and Hitchin so I boarded the late running 22:09 which was completely wedged, even right at the front of the train. I've rarely seen so many people get off a train at SVG but despite this the train left full and standing.

There didn't appear to be any trains operating to stations between Hitchin and Peterborough. Staff were trying to sort out aoternatives for passengers going towards Peterborough, they were doing a good job in the circumstances but looked stressed which given the circumstances is understandable.

Not a good day on the GN side. Does anyone know what happened?

Rail replacement buses were operating until end of service to serve stations on the Peterborough line. These were at station staff instruction so it's possible not all trips were advertised on journey planners

== Doublepost prevention - post automatically merged: 29 Aug 2025 ==

Does anyone know why nothing ran through the core onto the GN side for the rest of the day?

There was a severe displacement of units and drivers so the service plan which had the shuttle services calculated remained in place

 

[AM9]

For something that has seen so much money thrown at it, the Thameslink core seems somewhat fragile.

The TL core probably has way less expenditure per passenger spent on it than any other high density route.

 

[Hadders]

There was a severe displacement of units and drivers so the service plan which had the shuttle services calculated remained in place

Where did the units that were north of the Thames at the time the incident occurred go?

I remember it being widely reported on this forum, by someone apparently in a position to know, that when there was disruption in the core it would be 'simple' to send trains to Kings Cross and turn trains there. Now clearly there isn't sufficient platform space to do this but what I don't understand is why an incident at 14:00 that was fixed by 18:00 (according to NRE) resulted in no trains running for the remainder of the day.

 

[jon0844]

For something that has seen so much money thrown at it, the Thameslink core seems somewhat fragile.

Personally, I think the core has been a lot better than I ever expected/feared it to be. Power issues are always going to be pretty devastating, but when there are train issues the quick implementation of the bi-directional operation and knocking out services (because there's no way to operate at a high frequency with just one line) usually keeps some sort of service going.

Having ECS services not dropping the pan before Blackfriars is still an ongoing issue though.

There are many other things that go wrong that causes more issues!

 

[Magdalia]

I suppose on the flip side, capacity wise it's pushed to the very limit.
I can't imagine there are many 2-track heavy-rail stations that have the service frequency that Thameslink core gets.

The Thameslink core has never been pushed to the limit in timetables. It is designed for maximum 24tph.

The Elizabeth Line core has a higher frequency, I think 26tph?

Where did the units that were north of the Thames at the time the incident occurred go?

I saw 2 of them in the sidings at Cambridge. The next 2 Cambridge-Brighton trains following the failure seem to have gone into Kings Cross and then presumably empty to Hornsey. Another Cambridge-Brighton terminated at Welwyn Garden City and ran empty to Hornsey from there.

 

[43066]

For something that has seen so much money thrown at it, the Thameslink core seems somewhat fragile.

It doesn’t, actually. Hardly any of the issues Thameslink suffers are due to the core. The majority of problems are down to insufficient crew/delays occurring on other parts of the network.

 

[Nicholas Lewis]

Personally, I think the core has been a lot better than I ever expected/feared it to be. Power issues are always going to be pretty devastating, but when there are train issues the quick implementation of the bi-directional operation and knocking out services (because there's no way to operate at a high frequency with just one line) usually keeps some sort of service going.

Thameslink works extremely well and whilst not such a big people mover as Elizabeth line its still a key part of London & SE infrastructure. However when anything goes wrong on the main North to South routes (not Sutton Loop) it takes out multiple service groups and last Thursday was just another example. The irony was at the time of the incident the signaller was working around the problem to keep trains moving but by 1400 virtually the entire Thameslink service was suspended maybe a necessity to deal with the stranded train so fair enough. TLK Twitter site reported the stranded removed by 1700 yet service restoration was utterly woeful and i would say one of the worst ever by Thameslink. The fact that Hitchin to Peterborough was reduced to a bus service should have every MP on that route on Heidi Alexanders case about how that could happen for an issue 40 miles away.

We are now 7yrs on from the 2018 timetable so you would have thought by now between GTR and NR they would have honed better contingency plans although I will give them some slight credit in that they attempted to run a Horsham to London Bridge Ctl service but it was very erratic.

 

[TFN]

The Elizabeth Line core has a higher frequency, I think 26tph?

It runs 24tph in the peaks with capacity for more (I believe more than 30).

 

[Spartacus]

It doesn’t, actually. Hardly any of the issues Thameslink suffers are due to the core. The majority of problems are down to insufficient crew/delays occurring on other parts of the network.

That the trouble with that kind of bottleneck between effectively two linked networks, it's bound to concentrate then spread delays from one to another.

 

[Horizon22]

It runs 24tph in the peaks with capacity for more (I believe more than 30).

30tph, 11 car trains is the theoretical maximum.

== Doublepost prevention - post automatically merged: 1 Sep 2025 ==

Thameslink works extremely well and whilst not such a big people mover as Elizabeth line its still a key part of London & SE infrastructure. However when anything goes wrong on the main North to South routes (not Sutton Loop) it takes out multiple service groups and last Thursday was just another example. The irony was at the time of the incident the signaller was working around the problem to keep trains moving but by 1400 virtually the entire Thameslink service was suspended maybe a necessity to deal with the stranded train so fair enough. TLK Twitter site reported the stranded removed by 1700 yet service restoration was utterly woeful and i would say one of the worst ever by Thameslink. The fact that Hitchin to Peterborough was reduced to a bus service should have every MP on that route on Heidi Alexanders case about how that could happen for an issue 40 miles away.

If the core of the Elizabeth line goes wrong, it complete messes up that service too and spreads outwards, and if it is closed for an extended period (> 1 hour), then a reduced service would run from Liverpool St NR and a significantly reduced service from Paddington NR.

This is mainly due to platform availability whilst weaving into the booked train plan for the other operators. The same is almost certainly true of Thameslink - Kings Cross and London Bridge respectively will fill up very quickly without confirmed departures - with the extra problems of a) much longer end-to-end running which means stepping back / more crew risks and b) considerably more branches to look at serving, c) lots of interworking.

Perhaps Thameslink need stronger service plans to build into the contingency plans that will be introduced if the core is shut.

 

[Harpo]

Perhaps Thameslink need stronger service plans to build into the contingency plans that will be introduced if the core is shut.

On many routes, once it was running, it could often be very difficult to get out of a contingency plan before end of service especially if crew would go out of hours by trying to reinstate long distance working.

The Thameslink contingency plan sounds like it’s very difficult to get into, suggesting that it’s incomplete and has blockers that need removing.

At the risk of sounding like a broken record, these are also occasions where something akin to a depot Traincrew Supervisor role could usefully supplement the poor sods manning a couple of control office phones, a role that local managers could usefully do.

 

[zwk500]

It's my understanding, actually, that GTR are not even running all of the services that were originally planned to operate through the core. is that what we now call "pushed to the very limit"?

It was designed to run 24tph, I think it's had up to 20tph at the busiest. But that's still a very high capacity utilisation for a legacy line heavily retrofitted, whereas Crossrail was designed for the high throughput from the start.

Considering constraints like the gradient profile, station placement, and tight curvature, it is still reasonable to describe the capacity as being pushed to the limit, although possibly not the "very" limit.

 

[bramling]

30tph, 11 car trains is the theoretical maximum.

== Doublepost prevention - post automatically merged: 1 Sep 2025 ==



If the core of the Elizabeth line goes wrong, it complete messes up that service too and spreads outwards, and if it is closed for an extended period (> 1 hour), then a reduced service would run from Liverpool St NR and a significantly reduced service from Paddington NR.

This is mainly due to platform availability whilst weaving into the booked train plan for the other operators. The same is almost certainly true of Thameslink - Kings Cross and London Bridge respectively will fill up very quickly without confirmed departures - with the extra problems of a) much longer end-to-end running which means stepping back / more crew risks and b) considerably more branches to look at serving, c) lots of interworking.

Perhaps Thameslink need stronger service plans to build into the contingency plans that will be introduced if the core is shut.

The impression I get with Thameslink is that control just cannot cope during disruption. So if something happens anywhere on a route, the service just seems to disappear, there is rarely any attempt to introduce shuttle services or anything like that. It seems they have enough trouble just dealing with the trains which are out on the railway, let alone implementing alternative arrangements.

And if more than one route is involved the whole thing melts down. The other issue is that the service also doesn’t recover well - any problem after about 1400 and that’s it for the rest of the day. Again points to poor crew management.

Meanwhile, there’s still random “due to train crew unavailable” cancellations across the board, worse if your service happens to be one of the GN services booked for 379s.

 

[Harpo]

The impression I get with Thameslink is that control just cannot cope during disruption.

points to poor crew management.

Signalling positions are sized to cope with perturbation. I suspect that many TOC controls are not. (See my post above.)

 

[Bald Rick]

It was designed to run 24tph, I think it's had up to 20tph at the busiest.

There were 22tph in the peak pre Covid, and there 21tph each morning (southbound, any 60 minutes departing St P from 0742 to 0850)

The impression I get with Thameslink is that control just cannot cope during disruption. So if something happens anywhere on a route, the service just seems to disappear, there is rarely any attempt to introduce shuttle services or anything like that. It seems they have enough trouble just dealing with the trains which are out on the railway, let alone implementing alternative arrangements.

it’s fairer to say that the traincrew arrangements on TL make it an order of magnitude harder to manage around an incident and recover from it than it does on the Elizabeth line (or the underground, or Overground, c2c, etc). And with TLs current crew issues, that makes it even harder. This is amplified with any major incident.

 

[bramling]

it’s fairer to say that the traincrew arrangements on TL make it an order of magnitude harder to manage around an incident and recover from it than it does on the Elizabeth line (or the underground, or Overground, c2c, etc). And with TLs current crew issues, that makes it even harder. This is amplified with any major incident.

Wow, seven years and four months in, and finally a statement essentially saying that Thameslink in its post-2018 form is inherently unreliable!

I presume part of the issue is that Horsham-Peterborough and Brighton-Cambridge are both too long to be able to crew entirely from the ends. If your ideal driver diagram would be two out and back end-to-end trips, it seems that diagrams can’t be constructed in this way. If this can’t be improved upon, or does of course beg the question as to whether these services should be operated in their current form.

Meanwhile, on GN we now have a new issue, namely the 379s. I’ve been unlucky enough these last few days to be attempting to be using a service booked for 379s, and at the moment their existence is somewhat mythical. So far I’ve got just a 50% success rate of the service running. Should GN be getting rid of 387s so quickly when the 379s, for whatever reason, are flaky?

 

[43066]

Wow, seven years and four months in, and finally a statement essentially saying that Thameslink in its post-2018 form is inherently unreliable!

I presume part of the issue is that Horsham-Peterborough and Brighton-Cambridge are both too long to be able to crew entirely from the ends. If your ideal driver diagram would be two out and back end-to-end trips, it seems that diagrams can’t be constructed in this way. If this can’t be improved upon, or does of course beg the question as to whether these services should be operated in their current form.

Meanwhile, on GN we now have a new issue, namely the 379s. I’ve been unlucky enough these last few days to be attempting to be using a service booked for 379s, and at the moment their existence is somewhat mythical. So far I’ve got just a 50% success rate of the service running. Should GN be getting rid of 387s so quickly when the 379s, for whatever reason, are flaky?

A lot of the crewing issues existed even pre 2018 - namely Thameslink relying very heavily on overtime. The 2018 version of Thameslink had included negotiations for changes such as more committed Sundays for new joiners to the grade, Blackfriars depot being closed and drivers redeployed, new depots being created etc. that were meant to resolve the situation, but clearly haven’t done so. In fact the more limited route knowledge and much less flexibility to cross cover work may well have made it worse.

 

[Nicholas Lewis]

Wow, seven years and four months in, and finally a statement essentially saying that Thameslink in its post-2018 form is inherently unreliable!


I presume part of the issue is that Horsham-Peterborough and Brighton-Cambridge are both too long to be able to crew entirely from the ends. If your ideal driver diagram would be two out and back end-to-end trips, it seems that diagrams can’t be constructed in this way. If this can’t be improved upon, or does of course beg the question as to whether these services should be operated in their current form.

You still get crew changes at Finsbury Pk on many services on the above routes in my experience. In fact if this is standard it ought to make it easier to drop back to shuttles either side of the core when their are issues. And to be fair they did attempt a Horsham L.Bdge Ctl service last week but it fell apart after a few hours. Then unusually on the Nth side they didn't put in a KX-Peterborough service which has been used previously. My experience after 7yrs of using Tlk services is its so erratic how they deal with each incident and maybe suggests no off the shelf contingency plan.

 

[Bald Rick]

Wow, seven years and four months in, and finally a statement essentially saying that Thameslink in its post-2018 form is inherently unreliable!

It doesnt say that at all!

 

[Gostav]

It was designed to run 24tph, I think it's had up to 20tph at the busiest. But that's still a very high capacity utilisation for a legacy line heavily retrofitted, whereas Crossrail was designed for the high throughput from the start.

Considering constraints like the gradient profile, station placement, and tight curvature, it is still reasonable to describe the capacity as being pushed to the limit, although possibly not the "very" limit.

It seems like the most severe limitation is that all flat junctions on the route.