Transport for Wales Class 231 / 756 Stadler FLIRTs

[nigelsporne]

My Engineering Mag. states that the Rhymney wires have gone live.
Have the 756s started training at all on this line?

 

[MikePJ]

My Engineering Mag. states that the Rhymney wires have gone live.
Have the 756s started training at all on this line?

Not that we've seen, and in fact whilst TfW have put out press releases saying that the wires are live, no-one from the group has yet confirmed that traincrew have been briefed or that construction earthing straps have been removed. Given that TfW have previously put out misleading press releases about wires going live, I would remain skeptical until we've seen hard evidence.

I've been keeping an eye on RTT for any test movements to Rhymney and nothing has yet appeared, so unless anyone else has evidence to the contrary, I don't think we've seen any post-energisation testing (which on the discontinuous electrification system also includes confirming that all the power changeover beacons are working), let alone any training movements.

 

[Bob Price]

There are runs to Cheltenham Spa in the wee small hours on the 16th December. 5Q20 from Cardiff Canton to Cheltenham then 5Q21 back. These may be 231 testing

 

[BillStampy]

There are runs to Cheltenham Spa in the wee small hours on the 16th December. 5Q20 from Cardiff Canton to Cheltenham then 5Q21 back. These may be 231 testing

Similar to the runs to Maesteg and Ebbw Vale on the same night last week. Good to see something's happening in the background.

 

[james1996]

Is anyone able to explain what Platform Identification Beacon System (PIBS) are? and the difference between them and SDO

 

[nigelsporne]

With the advent of the recent Timetable change has there been any significant changes to the diagrams worked by 756/231s?
What are the reliability figures for these units these days?

 

[Rhydgaled]

Is anyone able to explain what Platform Identification Beacon System (PIBS) are? and the difference between them and SDO

I can't answer that in any detail, but it seems to me that SDO (Selective Door Openning (or should that be Operation?)) is quite a broad term. I think SDO can be completely manual (as on First Great Western slam-door HSTs where, I believe, the guard was able to unlock only those doors in front or behind their local door rather than every door on the train, for use at short platforms) but can also include various systems. Another term I've seen used on this forum is ASDO (the A being 'Automatic') where, I think, the selection of which door(s) will unlock at each stop is done automatically by the train without any selection being done by the crew. My guess (and it is just a guess), is that PIBS is a component of an ASDO system.

 

[Pete_uk]

Any idea as to when the Flirts will make regular appearances on the Cheltenham to Maesteg/Cardiff runs?

 

[trainspotter4]

Any idea as to when the Flirts will make regular appearances on the Cheltenham to Maesteg/Cardiff runs?

I think this very much depends still on the 398 introduction, to cascade the the 756s to Rhymney and then finally 231s to Cheltenham/Ebbw/Maesteg. Driver training is reported to be in progress for mainline drivers on the 231s and of course we've seen the fuel test runs in recent weeks so shows they're still planning on doing this as soon as possible (as things were very much quiet on this final cascade until those fuelling runs). And let's be fair anything to free up 197s is a good thing too. Though only eight out of eleven are booked on a given day, so there might come a time where maybe they run a 231 on a single diagram assuming they have spares for Rhymney still to get the ball rolling, even if inconsistently but speculative that is (in theory there isn't much stopping this now assuming enough drivers are trained to not shoot themselves in the foot by doing it, assuming none of the three routes needs SDO works etc - I don't think so? then maybe if 150 numbers start dwindling and the bigger cascade hasn't happened yet, we may see it early)? That's another point, does anyone know if anything more has been said on retrofitting pantographs to 231s yet?

 

[positron]

Last I heard the idea of the conversion was presented but they didn't publish wether the decision had been taken. It seems a no brainer, wouldn't be surprised if the ROSCO themselves decided it's worth doing.

 

[tfw756rider]

Last I heard the idea of the conversion was presented but they didn't publish wether the decision had been taken. It seems a no brainer, wouldn't be surprised if the ROSCO themselves decided it's worth doing.

I wonder how such a decision works with this mouthful of a ROSCO (SMBC Leasing and Equitix, supported by Apex Rail and IPEX Consulting) compared with just... (for example) Porterbrook?

 

[MikePJ]

One issue under discussion at the time was that Stadler wanted to do the conversions in Switzerland, which would mean a long and expensive transit of each unit back to the factory. TfW were trying to persuade Stadler to do the work in the UK.

 

[trainspotter4]

One issue under discussion at the time was that Stadler wanted to do the conversions in Switzerland, which would mean a long and expensive transit of each unit back to the factory. TfW were trying to persuade Stadler to do the work in the UK.

Yeah, I also heard this too which makes sense let's be fair for TfW to reduce cost/out of service time as much as able, all depends on whether Stadler can slash wish to entertain doing it in the UK. It definitely is a no brainer with these units due to work quite a lot under wires, especially if (pure speculation here) Amey/TfW took responsibility say in the future for Ebbw Vale line (potential electrification options there) and there is enough electrification currently to justify doing it, I suppose as well if they time it right, they could do it during the swap for 231s from Rhymney to mainline (for a bit anyway as it is rumoured to take quite some time per unit to do)?

 

[tfw756rider]

One issue under discussion at the time was that Stadler wanted to do the conversions in Switzerland, which would mean a long and expensive transit of each unit back to the factory. TfW were trying to persuade Stadler to do the work in the UK.

Where did you see/hear this?

 

[MikePJ]

I’m pretty sure I saw it in a press article, but can’t find it now… but it is briefly mentioned without sourcing upthread: https://www.railforums.co.uk/thread...ss-231-756-stadler-flirts.220379/post-7129250

== Doublepost prevention - post automatically merged: 3 Jan 2026 ==

Rail magazine mentions that the conversion would be very slow and done one at a time. https://www.railmagazine.com/news/f...converting-class-231-fleet-into-bi-mode-units

TfW has until April 30, 2026, to decide if it wishes to activate the notice.

A spokesman said: “If it does go ahead it will take up to four years to complete, with the all 11 units being converted from diesel only to bi-mode trains (pantograph conversion), one unit at a time.”

 

[BillStampy]

There are runs to Cheltenham Spa in the wee small hours on the 16th December. 5Q20 from Cardiff Canton to Cheltenham then 5Q21 back. These may be 231 testing

Just went back to take a look at what ran, 231004 on RTT.
Hopefully we'll have a unit in service on Maesteg/Ebbw/Cheltenham this year in 2026 considering the 398s shouldn't be entirely too far (fingers crossed!)

 

[Jez]

Just went back to take a look at what ran, 231004 on RTT.
Hopefully we'll have a unit in service on Maesteg/Ebbw/Cheltenham this year in 2026 considering the 398s shouldn't be entirely too far (fingers crossed!)

We are likely to see a gradual introduction of them appearing on those routes I guess? I wonder if they might decide to do Cheltenham first given it needs 3 diagrams compared to Maesteg to Ebbw Vale needing 4.

 

[Last Hurrah]

If 231 units have pantographs fitted for mainline running, would this be this be an appropriate time to go from 4 car to 5 cars

 

[nigelsporne]

Once the 231s are on their allotted diagrams are there any plans for service enhancements bearing in mind there are only 7 diagrams according to the post above? Does this number include the Ebbw to Newport service?
Although it may be nice to have the units with a pantograph is this really justified with only the Cardiff to the Tunnel with wires?

 

[CapitalStar378]

Once the 231s are on their allotted diagrams are there any plans for service enhancements bearing in mind there are only 7 diagrams according to the post above? Does this number include the Ebbw to Newport service?
Although it may be nice to have the units with a pantograph is this really justified with only the Cardiff to the Tunnel with wires?

I think the idea would be to use them for Cardiff to Bristol services and the wires would be used through the tunnel and for a while after.

 

[nigelsporne]

Thank you.

 

[Rhydgaled]

Once the 231s are on their allotted diagrams are there any plans for service enhancements bearing in mind there are only 7 diagrams according to the post above? Does this number include the Ebbw to Newport service?
Although it may be nice to have the units with a pantograph is this really justified with only the Cardiff to the Tunnel with wires?

As well as the possible future services to/from Bristol mentioned by CapitalStar378 above, Severn Tunnel Junction is roughly a third of the way between Cardiff Central and Cheltenham Spa (21mi 50ch and 41mi 27ch according to RailMiles). While burning diesel under the wires for over 21miles is probably fairly limited when compared to what happens elsewhere in GB, I wouldn't call it negligible. Also, the Welsh Government seems to want more electrification (Crewe to Holyhead and Cardiff to Swansea at least) but want the UK Government to pay. If TfW continue to burn diesel under the wires that already exist after they could have fitted the 231s with pantographs, the UK Government might be even less likely to fund more wires in future?

 

[John R]

Is the proposal to make them bi-mode, or to be compatible with the existing tri-mode 756 fleet? If the latter, then judging by comments about the 756s being able to get to Bridgend and back via the Vale on battery then then they would be able to do at least two thirds of the journey to Cheltenham without resorting to diesel.

 

[Jez]

Once the 231s are on their allotted diagrams are there any plans for service enhancements bearing in mind there are only 7 diagrams according to the post above? Does this number include the Ebbw to Newport service?
Although it may be nice to have the units with a pantograph is this really justified with only the Cardiff to the Tunnel with wires?

If there are 7 diagrams that would cover just the Maesteg-Ebbw Vale and Cheltenham services. I could be wrong and lots has changed since then, but im sure it was said the Newport to Ebbw Vale would be 197s once the 231's move onto the Maesteg-Ebbw Vale service. Unless they can stretch it to 9 diagrams out of 11 units. Would 4 cars on Newport to Ebbw Vale be too many carriages?

 

[John R]

7/11 (64% availability) would seem very low for any fleet once it has gone through any teething troubles after introduction. I would have thought 9 diagrams would be more likely eventually for the 231s.

 

[Caaardiff]

I think the idea would be to use them for Cardiff to Bristol services and the wires would be used through the tunnel and for a while after.

Cardiff - Bristol has been said will be run by services from West Wales, so will likely be 197s.
In the long term they could run them Swansea - Bristol all stops but I believe the aspirations is a direct link to Bristol from further in West Wales

 

[John R]

Cardiff - Bristol has been said will be run by services from West Wales, so will likely be 197s.
In the long term they could run them Swansea - Bristol all stops but I believe the aspirations is a direct link to Bristol from further in West Wales

There are two proposals I believe. The one you refer to, to extend West Wales services to Bristol every two hours for which a Track Access application has gone in, and which could start this year.

Then there is the half hourly stopper calling at the new Burns stations for which funding was confirmed last year, but will take a couple more years to see the light of day.

 

[Philip Roberts]

If there are 7 diagrams that would cover just the Maesteg-Ebbw Vale and Cheltenham services. I could be wrong and lots has changed since then, but im sure it was said the Newport to Ebbw Vale would be 197s once the 231's move onto the Maesteg-Ebbw Vale service. Unless they can stretch it to 9 diagrams out of 11 units. Would 4 cars on Newport to Ebbw Vale be too many carriages?

A two car 197 could happily serve Newport-Ebbw Vale. A three car 231 seems a bit excessive for that service (it's my local service so am not running it down). Back on early metro maps, it showed a Ebbw Vale-Abergavenny service via Newport but I'm not sure that's still a possibility

 

[tfw756rider]

A two car 197 could happily serve Newport-Ebbw Vale. A three car 231 seems a bit excessive for that service (it's my local service so am not running it down). Back on early metro maps, it showed a Ebbw Vale-Abergavenny service via Newport but I'm not sure that's still a possibility

All the 231s are 4-coach; only the 756s have both 3-coach and 4-coach variants.

== Doublepost prevention - post automatically merged: 7 Jan 2026 ==

Is the proposal to make them bi-mode, or to be compatible with the existing tri-mode 756 fleet? If the latter, then judging by comments about the 756s being able to get to Bridgend and back via the Vale on battery then then they would be able to do at least two thirds of the journey to Cheltenham without resorting to diesel.

My understanding is bi-mode, so they'd be more like 755s.

 

[Philip Roberts]

All the 231s are 4-coach; only the 756s have both 3-coach and 4-coach variants.

== Doublepost prevention - post automatically merged: 7 Jan 2026 ==


My understanding is bi-mode, so they'd be more like 755s.

Ah, cheers. I hadn't realised. It makes a 231 even harder to justify on Ebbw-Newport