tfw756rider
On Moderation
It's almost as if the Swiss part of Stadler really doesn't really want much to do with the Spanish part of Stadler. "Not our problem"...
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TfW class 398 Stadler Citylink tram trains
- Thread starter Bob Price
- Start date
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R
RailUK Forums
Very common on light rail vehicles. Typically used as emergency brakes when street running. I’m sure someone from one of the UK light rail systems can give more details than I can.
Right - so the motors are connected directly to the overhead power in the sense that the battery is not between the two, rather than power always somehow flowing through the batteries as was originally suggested.
Even without batteries being involved wouldn't AC motors require rectifying and re-inverting the power anyway, otherwise they'd only be able to operate at a speed defined by the line frequency?
chargesmith
Member
I agree - whilst maintaining respect to the poster we shouldn't take unverified information too seriously.
We'll know in a few months if the situation is that dire, but I suspect the apparent list of faults isn't a million miles away from what the 756s had a few months prior to service and they are very reliable now in my experience as a user.
Whilst the battery capacity is smaller the units are smaller and therefore lighter too, so whilst I wouldn't expect them to match the 756s range it should be sufficient. Even if it is only 6 miles as reported, that's more than enough to get through the largest non-electrified section (less than 3 miles) and provided all non-essential systems are powered down if there's disruption the train will likely use very little power while idle.
If it does turn out to be a more common issue adding a similar system to the bay platform at Caerphilly for trains to recharge when at platform to even one of the stations on the non-electrified sections would likely do the trick.
I also sincerely doubt that a company like Stadler have any incentive to deliver a product that's not fit for the purpose it's intended for even if someone messed up the procurement (which I also think is unlikely).
Let's just see what happens. As I said earlier people doubted the 756s would ever be ready too.
Clearly from Stadler's point of view, the customer ordered a slightly modified tram. What they have received is, indeed, a slightly modified tram. And it's very similar to the other UK application of slightly modified tram in its sister the class 399. How exactly one can be shocked that if one cheaps out and orders a tram to do the job of what has been for many, many decades a very technically different suburban commuter train, it then comes up against many operational barriers, I don't know.
The Stadler Metro (as an example) is a great fit for the Valleys services. The Stadler Citylink really isn't. In Rotherham the Citylinks are a perfect fit, because what's required is over 80% street running (mostly on dedicated tracks yes, but without the need to comply with the expensive Network Rail standard) and the easier 750v DC supply.
The Stadler Metro (as an example) is a great fit for the Valleys services. The Stadler Citylink really isn't. In Rotherham the Citylinks are a perfect fit, because what's required is over 80% street running (mostly on dedicated tracks yes, but without the need to comply with the expensive Network Rail standard) and the easier 750v DC supply.
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tfw756rider
On Moderation
What has the date that @VR494 joined this site got to do with anything? They've literally said things from the point of view of someone who has clearly been involved with the 398s and been on the test runs and may have worked at Taffs Well depot, you know?
If this site was Wikipedia, I'd understand the claims of "unverified information" and a "dubious source", but it isn't. This site is RailUKforums, where people who are involved with train introduction provide information to us about it (which they don't have to, by the way), and I really appreciate that.
Maybe, but despite my username, and that it may not yet be obvious to users of the 756s, I'm not going to ignore that @VR494 said that even they have started to have battery issues.
I doubt they do too, but, as both @VR494 and I have already tried explaining, the 398s are from the Spanish part of Stadler, which was formerly another company (Vossloh), or part of it.
If you look at post #961 (including the quotes), it almost looks as if the Swiss part of Stadler (231s and 756s) are happy that they've done their job, with no mention of the 398s, which aren't their problem.
Indeed - surely all the issues with the 398s (and the battery issues the 756s have started to have) will be resolved at one point or another.
What they can and can't say is likely to be dictated by their legal department. No doubt that's why CAF did a 'no comment interview' - as is fairly common. Anything they do say may end up being used in evidence against them, regardless of how innocuous it seems without the benefit of hindsight.
Last Hurrah
Member
Need to add a few additional chains to that figure to cover distance from Ninian Park to first Electrification Mast - Sanatorium Road opposite Welsh Primary School - Ysgol Gymraeg Treganna
First Mast is roughly a third/halfway towards Waungron Park Station
Not quite - the batteries/BMS are between the rectifier and inverter, in that they are conneted to a common DC bus.
Modern AC locos and EMUs that use AC motors do have rectifiers and inverters, but they are usually combined into a single equipment cabinet called a traction converter. For a battery hybrid EMU the DC bus inside the converter cabinet needs to be made avaialble to connect the BMS to.
Some EMU designs do still have separate rectifiers and inverters as they distribute the traction current to inverters in each motor car via a DC bus. This is usually done for designs that can be built to run on AC and third rail DC.
chargesmith
Member
The same is true going the other way from Cathays towards Llandaff. The wires start near to the A48 overbridge just before the likely site of the future Gabalfa station.
However as I alluded to earlier in normal operation units will leave the non-electrified sections in both directions at line speed, meaning they will likely use very little power on traction until they leave the next station and may even recover some energy from regenerative braking.
Also I don't know where this idea that they can "only" do 6 miles on battery comes from - the battery range will vary depending on a lot of different factors including line gradient, the number of people aboard, ambient temperature (including AC and heat requirements that go with that), number of stops and driving style (among other factors) so I suspect 6 miles is more likely to be minimum range rather than a maximum.
Also need to add the fact that the pantograph will need to drop a safe distance before the end of the wires.
In the anticlockwise direction there won’t be much of a coast before Ninian Park, and they will also have the steep climb from a standing start between Central and Queen St, neither of which will be beneficial to the range.
In the anticlockwise direction there won’t be much of a coast before Ninian Park, and they will also have the steep climb from a standing start between Central and Queen St, neither of which will be beneficial to the range.
VR494
Member
Stadler have stated they have a range of about 6.2 miles or 10km on battery, as an estimated range. They were not designed to be driven around primarily on the battery, and require OHLE out of the box. Just like metrolink in Manchester.
However tfw wants to run them in a combined battery/overhead charge mode with beacons raising and lowering the pantograph, as well as opening and closing the VCB’s for neutral sections. Think of the battery as an added extra to allow shunt moves on and off a depot or into a sidings etc.
The issue with a combined battery and overhead mode as well is a bi-product of heat transfer from the battery, and the 756’s are having issues with ESS strings failing to connect, once they loose the 3rd out of 4th battery, which some are running around with only 3, the dynamic braking system also shuts off and reverts to pneumatic disc application. The train then has to come out of service.
The OHLE on the TAM is also earthed for vast majority, meaning it is pointless to trains running under it anyway. This is due to the low bridges other infrastructures they could not guarantee clearance from. On the CAR line, (Caerphilly and Rhymney) they went with a totally different design. The OLE can also support speeds of up to 75mph running, where the TAM (Treherbert, Aberdare and Merthyr) cannot. To operate between these sections the beacons also open and close the VCB and switch the train to battery only mode and back again as they go along. This is putting excessive wear on parts, and as stadler has pointed out they are not supposed to be doing this so frequently either. Pantograph wear is also becoming an issue and a few 398’s have had to lend parts to 756’s, pantographs for service.
Also if a train with pantograph up has to turn around in an area with earthed cables, the pantograph will automatically lower because no high voltage is detected by the train. You are unable to raise this again until under positive cables or out of a permanent earthed section.
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This is absolute nonsense. Some of the other "facts" stated in this thread recently make no sense either
Cardiff123
Established Member
I initially missed this - so 231s will move to mainline, presumably then the 756s will move over to Rhymney - Barry Island / Bridgend, with 150s going back on the TAM lines under the wires, whilst 398s sit at Taffs Well? How on earth will TfW spin that to the public?
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Peter Sarf
Established Member
+
I suppose the reality is that this really means
"The OHLE on the TAM is also earthed for the vast majority OF NEUTRAL SECTIONS," ?.
Which would make far more sense to me (a relative lay man).
The rest of the sentence is a bit odd.
I am more and more convinced that the 398 roll-out is reaching the stage where pessimism kicks in. But it is not necessarily correct (or helpful). It has happened with all new fleets to a greater or lesser extent and this is perhaps a lot more involved than just replacing 455s with 701s. Think more like the 810s with their new OHLE. I am not saying there are no problems BUT I am inclined to believe there is nothing spectacular. People close to other projects from the past may sympathise with this view. After all who said it was going to be a walk in the park.
EDIT 13:47
Mention up thread was made of the 398s needing yellow ends adding at a late stage and/or problems with the headlights. I might be wrong but if the head lights were bright enough for Network Rail use then they would very likely be far to bright and not dipped for road use. So a solution seems to be to revert to yellow ends to satisfy use on Network Rail lines and have not-too-bright lights for road use. But that is just my guess.
Furthermore the timetable of works for 2026 provided by @MikePJ on the South Wales 'Metro' updates thread is interesting.
It seems to show solutions for a number of the issues raised on this thread.
I will paste it here as quoting not working :-
Aha! That style of powerpoint Gantt chart looked very familiar and so your post prompted me to go and look at the consultation page, and indeed it is from the newly-released 2026 project plan ("G5 notice of intended scope") - see attached.
Here's a summary of what's supposed to happen this year:
- 31st January: Aberdare toilet completion
- 9th Feb: Merthyr Vale and Treorchy toilet completion
- End Feb: Merthyr Tyfil, Abercynon & Tonypandy toilet completion
- March 23rd: Cardiff Bay branch wires to go live
- March 31st: Ty-Glas platform extension entry into service; Cwmbach and Llwynypia toilet completion
- April to mid-June: 398s enter service on Cardiff Bay - Pontypridd services
- July - September: 398s replace 756s on the TAM lines and 756s replace 231s and 150s on Rhymney/Bargoed <> Barry Island services
- August - high voltage connection of Ninian Park Feeder station to core valley lines overhead line network
- October - Bute Town station (note that it's written as two words) Platform 2 opening.
- Dec 13th: No 150s on the TAM lines, new faster timetable. (Note that 150s on Rhymney will still be around because they're still needed for the Vale of Glamorgan service)
- Various unspecified level boarding works are also listed, as are various signalling and track works that I don't understand from the relatively cryptic notes.
Attachments
CVL G5 Notice of Intended Scope for the Transformation Programme to be implemented during 2026...pdf511.1 KB.
END of quote.
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So the connection is in between, but not the batteries themselves - the power doesn't flow through them ever. The bus is fed from the batteries and/or the overhead. It's not the case that the motors have a "direct" (via inverter) link only to the batteries, with a separate (rectified) connection between the overhead and the batteries used so that overhead power can be charging the batteries at the same time as they are providing power, as seemed to be suggested here and I've seen stated elsewhere on this forum.
I think it's quite possible that driver instruction is giving a (harmlessly?) incorrect description of how the system actually works.
It's great to have "inside" information given that TfW won't talk about these things.
But I'm confused by this. Perhaps my memory is playing me tricks, or I have misunderstood, but I thought that the KeolisAmey bid that won the franchise was based from the start around intermittent electrification to some extent. While the scheme we actually have isn't same as originally planned and may well have been descoped, I thought it was always expected that the 398s would have to use batteries in service, not just to avoid having to wire the new depot or sidings at termini. In particular I didn't think the plan had ever involved wiring Network Rail owned track.
Snow1964
Established Member
Partly, as they are based on trams, and not trains.
In most tram systems there is not the concept of neutral sections, balises/beacons and automatic circuit breakers. There might be short unelectrified sections but trams generally raise and lower pantographs at stops, off top of my head can't think of anywhere that trams raise/lower pantographs on the move.
Clearly the way TfW are trying to use them is not the way trams normally operate or are designed, where the driver is expected to coast through neutral sections, and system changes do not happen on the move.
If the battery range is about 10km (6.2 miles) then where the wires end (part way between stations) is inconsistent with this, because changing whilst stationary could exceed the Cardiff unwired gap. So answer is bit more complicated, didn't need to fully wire network, but where it was chosen to end the wires (which was often determined by a structure) is not consistent with tram based rolling stock.
That is very common, as an introduction is sometimes a very useful for drivers to have, but a fitter's detailed technical knowledge is obviously not required.
Indeed. When you add to this the factors about training and professional driving differences between staff authorised to work Network Rail lines and those trained to work on tramways, plus the fact that the supply isn't the usual DC, it's easy to see how even a great technical spec would run into stebacks with compatability.
VR494
Member
To clear any confusion, there are two kinds of neutral sections on the TAM lines. One is the gap between feeder stations, and on the mainline these are clearly sign posted and require the driver to coast through, with APC magnets opening and closing the VCB. The other kind we have on the CVL are PES, or permanent earthed sections of OLE. This where the requirement of 9ft from a structure could not be met.
The way trains operate on the CVL is different to the mainline, drivers are not required to coast through these sections, and the power controller is left open. The VCB is opened and closed by the track beacons (when they work) and closed again when clear of the section. The trains software automatically updates the mode after receiving each signal from the beacons.
There are also check 25kv signs provided for drivers to check the VCB has closed and power is drawing after passing through neutral sections, but not for the PES ones.
These are provided north of Llandaff and at Power station hill in the Trefforest estate area.
When I stated the vast majority of the TAM is earthed, when you add up all these PES sections of wire, it actually works out as considerable amount of cable, and you’d be very shocked if you saw the extent of it. The Treherbert line is the worst out of the three.
A map is provided showing these areas, however showing this to the public would obviously not be a good idea and could invoke cable theft plus other things. And all wires should be considered live at all times!
The feeder station at Ninian park I believe is related to the stable and charging on Canton depot, the wires are currently powered from Trefforest after being transferred from Didcot to local power sources.
At current there is still doubt about the amount of trains that can operate under the existing equipment and further stress tests will be required.
I’d also take all the above dates with a little optimism, current internal affairs paint a very different image of the document posted.
Testing of the 398’s is continuing and the team are working hard to get them out to you as soon as they realistically can with what they have to work with.
The way trains operate on the CVL is different to the mainline, drivers are not required to coast through these sections, and the power controller is left open. The VCB is opened and closed by the track beacons (when they work) and closed again when clear of the section. The trains software automatically updates the mode after receiving each signal from the beacons.
There are also check 25kv signs provided for drivers to check the VCB has closed and power is drawing after passing through neutral sections, but not for the PES ones.
These are provided north of Llandaff and at Power station hill in the Trefforest estate area.
When I stated the vast majority of the TAM is earthed, when you add up all these PES sections of wire, it actually works out as considerable amount of cable, and you’d be very shocked if you saw the extent of it. The Treherbert line is the worst out of the three.
A map is provided showing these areas, however showing this to the public would obviously not be a good idea and could invoke cable theft plus other things. And all wires should be considered live at all times!
The feeder station at Ninian park I believe is related to the stable and charging on Canton depot, the wires are currently powered from Trefforest after being transferred from Didcot to local power sources.
At current there is still doubt about the amount of trains that can operate under the existing equipment and further stress tests will be required.
I’d also take all the above dates with a little optimism, current internal affairs paint a very different image of the document posted.
Testing of the 398’s is continuing and the team are working hard to get them out to you as soon as they realistically can with what they have to work with.
Is it possible at this late stage to electrify more of the gaps so that they are shorter so they need to run on battery less or is it not possible anymore ?
VR494
Member
Unfortunately without the replacements of many bridges no.
Cardiff Queen street and Cathays area is also unable to have OLE due to sensitive brain scanning technology located in the area at a research facility.
The risk of a 398 becoming gapped is a real possibility and it’s not really an ideal situation.
Also because the 398’s won’t be interchangeable on the network, control will be unable to step sets up to cover services on the Rhymney and Vale lines etc when disruption occurs.
The discontinuities (no wires or wires which can't be energised) are there because they put up the wires according to where the spec could be met most cheaply. So yes clearly the work could be done, it's just that all of the areas which would need work are the most expensive places to work on. Hence the reason why on the Manchester and Edinburgh & Glasgow schemes vast millions were spent on reconstruction of large numbers of bridges and tunnels. In parts the engineering task was nearly as great as building a completely new line, but without the benefit of permanent access.
== Doublepost prevention - post automatically merged: ==
Again there are plenty of places where this already happens. It's just that it requires more money to ensure there are adequate barriers and protection against interference.
VR494
Member
There’s also an issue with the proposed door procedure, and testing has shown it to be time consuming.
At current the proposed procedure will be at an arrival station the train will read the platform dimensions from the ASDO beacon, this will then tell the TCMS how many doors to release. The driver will then release the doors, and correct side door enable will prevent an offside release.
For departure the train manager will signal 1-2 to the driver which will be repeated. The driver will then close the doors, check the PTI on the monitor and signal aspect and proceed. There will be no ready to start signal from the Train Manager.
A degraded method of work is being discussed whereby if rain water or of if driver is unable to see, would see the Train Manager dispatch in the usual way, closing the doors and giving a ready to start signal.
Aslef have put forward a proposal to have the guards close the doors and drivers only open them, as per GWR IET, however management are still pushing the latter despite concerns from testing.
This process will also apply to 756.
== Doublepost prevention - post automatically merged: ==
Also from December 2026 the new timetable will remove dwell time and the proposed 4 an hour could look something like this:
Treherbert would see two trains an hour to Cardiff Bay via Llandaff. Changes would see current Cardiff central services that terminate continue back to Treherbert via the city line, and there would be a new service introduced to enter Cardiff via the city line and return via Cathays. Creating a mega loop with the current Merthyr and Aberdare services.
Aberdare and Merthyr would see additional services to Cardiff bay added.
At current the proposed procedure will be at an arrival station the train will read the platform dimensions from the ASDO beacon, this will then tell the TCMS how many doors to release. The driver will then release the doors, and correct side door enable will prevent an offside release.
For departure the train manager will signal 1-2 to the driver which will be repeated. The driver will then close the doors, check the PTI on the monitor and signal aspect and proceed. There will be no ready to start signal from the Train Manager.
A degraded method of work is being discussed whereby if rain water or of if driver is unable to see, would see the Train Manager dispatch in the usual way, closing the doors and giving a ready to start signal.
Aslef have put forward a proposal to have the guards close the doors and drivers only open them, as per GWR IET, however management are still pushing the latter despite concerns from testing.
This process will also apply to 756.
== Doublepost prevention - post automatically merged: ==
Also from December 2026 the new timetable will remove dwell time and the proposed 4 an hour could look something like this:
Treherbert would see two trains an hour to Cardiff Bay via Llandaff. Changes would see current Cardiff central services that terminate continue back to Treherbert via the city line, and there would be a new service introduced to enter Cardiff via the city line and return via Cathays. Creating a mega loop with the current Merthyr and Aberdare services.
Aberdare and Merthyr would see additional services to Cardiff bay added.
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There's already a map of PES which doesn't look anywhere as extensive as you are saying. Are you saying it's more than this? https://tfw.wales/sites/default/files/2021-10/tfw_interactive map_02.pdf
VR494
Member
The attached map appears to be open source, what it does not show is the length of the cable network which is earthed. Internal maps however do show this for driver training regarding beacons, I will not confirm locations for reasons mentioned.
It is possible I will however disclose for a train to be in a specific area for a considerable amount of time, even under the wires and not be receiving anything from the 25kv.
The 756’s are currently able to use backup generators to top up, the 398’s will not have this capability.
Current CVL drivers are also going to have to learn to operate 398’s in line of sight conditions, i.e. tram driving, and will also be operating these on the road when it is up and running. This is something many current train drivers may become upset about, and opens up the doors about whether they will retain ETDL compliance going forward with the CVL TAM lines planned to be a separate entity form the rest of the network.
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Hmm...I apologise for going slightly off-topic here, but what on earth qualifies them to be called a "train manager"? They're on what is basically just a fancy tram, not a train, and they won't even be allowed to "manage" the doors. TM makes more sense when they have control of the doors and various other jobs, not when they're basically a buzzer-pressing RPI.
Considering it's from the TfW website, I highly doubt it's open source.
Snow1964
Established Member
Why on earth did they go for the faff of ASDO when unlikely to have more than 3 units coupled (121m or 395 feet long) considering how much work has been done on the platforms.
Two units coupled are no longer than a 756 at 81m or 265 feet long, and how many workings are expected to be booked for more than double units anyway.
It makes me wonder how anyone thinks slowing the door procedure, and cost and long term reliability of ASDO equipment is better choice than adding a few metres of platform, on lines that were having line closures for work anyway.
Might be a bit out of date though as it seems to show new double tracking towards Penarth which I belive is no longer planned.
I certainly find it somewhat hard to believe that if a conventional electrification scheme had been planned it would still have needed a gap because of this.
I had assumed that the reason that the Rhymney line electrification uses surge protectors to allow close clearances to bridges was because it was done later and this method wasn't available or hadn't been considered in the earlier schemes.
If there's a reason that it couldn't and can't be used on the routes through Pontypridd I'd be fascinated to hear what that is.
Also some of the permanently earthed sections seem to be entirely due to footbridges so the costs of raising them would be nothing like the cost of lifting road bridges.
And something else that's just occurred to me...
I was never sure quite what was being learnt by the Sheffield tram-train trial given that tram-trains are already established technology, just not in the UK. But then we've then jumped from that straight into the TfW discontinuous electrification tram-train scheme which is much more complex and I think something with little experience outside the UK.
Good questions! And I agree about Rotherham, where the spec was to extend a tramway service over a very short section of railway. On the Core Valleys infrastructure the spec was to extend a railway service over a very short section of street running.