Spot on. Six months of discussion so far. The driver had a couple of minutes.
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Incident at Talerddig, Wales - 21/10/2024
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Yes I'm quite conscious that by asking questions around the radio calls I'm in danger of carrying out a character assassination on the driver in question due to the advantage of having hindsight and being sat in my comfy armchair (well, figuratively, I'm sadly not in an arm chair at the moment!) rather than at the pointy end of a train I cannot make stop but that really isn't my intent and hopefully won't be taken that way by anyone reading it!
millemille
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Wasn't said as a dig at you or you anyone else
trundlewagon
Member
There was also the case of the runaway sleeper a few years ago, where the driver opted not to hit the big red button and this was noted as a smart move as it allowed trains to keep moving and keep a clear path ahead.
That may have gone through the driver's mind, knowing they were about to run through a junction and there may have been a chance the other train could pass through in time.
Did the train know that it was sliding though? If individual axles have a difference in speed it can tell, but if the whole lot locks up in one go then the speedo will just drop to zero and the unit will think that it has stopped.
computerSaysNo
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I've had some thoughts which I'm hoping can be clarified.
The driver used the standard radio call function while the train was still in the loop. If, during that call, it becomes apparent that the train will be unable to stop before unsafely exiting the loop, is the Emergency radio function able to be used without suspending the ongoing standard call? Also, is the signaller able to issue the automatic emergency stop of nearby trains with the calling driver on the standard call without interrupting that call?
Secondly, the report says "the call with the signaller ended, as the train ran through the points and exited Talerddig Up Loop". I note this is worded as the call ending without explicitly saying that the driver or the signaller chose to end it. In addition, sometimes the word "as" is used interchangeably with the word "because". To me then that sentence could be read "the call ended because the train ran through the points and exited the loop" i.e. the signalling system (or really anything other than the driver or signaller) ended the call automatically (or lost reception etc) without the consent or input of the driver or signaller). Was or could this have been the case?
PG
Established Member
I'm wondering if this might be a recommendation in the final report, something along the lines of 'correct operation to be tested at the first available opportunity' rather than running all day with the system untested?
greatkingrat
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Realistically, there won't be an available opportunity as the train will always be at a platform. Unless you want the train to stop between stations and the driver to climb down to the cess to test the sander?
edwin_m
Veteran Member
I can't speak for the 158, but more modern WSP systems do things like noticing abnormal deceleration and even releasing the brake on one axle to get a true reading of speed. I think some may even have Doppler radio to measure actual speed over the ground.
vikingdriver
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At my TOC, our autumn brief for last year specifically stated that if you are certain you are going to slide past a signal at danger, make an urgent call to the signaller. So a bit more than a regular call but not as as full on as a REC call either!
PG
Established Member
No, that is probably stretching 'first available opportunity' too far. Could a turnback siding be a suitable location?
Y Ddraig Coch
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Quite often trains are stabled over night at other locations than stations with platforms.
In TfW land take Chester and Holyhead as jist two examples where they are often stabled away from platforms on sidings.
Chester is incredibly congested and therefore all five bay platforms will have units stabled in them overnight. Middle Yard is grossly inadequate. Units stabled in platforms will only receive an above-solebar prep.
andythebrave
Member
As a complete non expert in these things I have what may seem a couple of foolish questions; in the dark, with little or no external visual points of reference, is it possible to have spatial disorientation?
By which I mean with emergency brake level applied and (possibly) an indicated speed of zero the actual increase in speed would not be perceived and, indeed, a deceleration could be assumed?
Also, once an emergency brake setting is applied can it be released at any time so cadence braking can be effected?
By which I mean with emergency brake level applied and (possibly) an indicated speed of zero the actual increase in speed would not be perceived and, indeed, a deceleration could be assumed?
Also, once an emergency brake setting is applied can it be released at any time so cadence braking can be effected?
I believe that on most units, once emergency braking is selected/commanded, it cannot be released until the unit is at a stand. Fairly sure the 158's are one such, though not sure how this works if the train is in an all sheel slide and the train thinks it has come to a stop already
millemille
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The Faiveley WSP system fitted to the class 158's is capable of detecting if all 4 axles are exceeding the allowed creep ratio and/or decelerating too quickly and has a nominal deceleration curve that it can use for reference to drive the speedo and to also keep the WSP operating, irrespective of what the axles are doing. The suggestion of WSP activity ceasing because all 4 axles sliding and reference speed being lost was put to bed during the Salisbury Tunnel investigation.
And there isn't a WSP activity lamp on the desk on the TfW class 158's, the driver can potentially see that the WSP is operating from the Brake Cylinder pressure gauge needle bouncing.
The TFW class 158's have a digital speedometer driven by the ERTMS system so it is reasonable to assume, as ERTMS uses two separate sources of train speed, that it would not drop to zero even if the WSP did lose control and cease to produce a reliable speed over ground signal.
And there isn't a WSP activity lamp on the desk on the TfW class 158's, the driver can potentially see that the WSP is operating from the Brake Cylinder pressure gauge needle bouncing.
The TFW class 158's have a digital speedometer driven by the ERTMS system so it is reasonable to assume, as ERTMS uses two separate sources of train speed, that it would not drop to zero even if the WSP did lose control and cease to produce a reliable speed over ground signal.
Annetts key
Established Member
A couple of thoughts on this.
I agree that some kind of test that can be done before the unit enters service each day is good practice. If units regularly stable in locations where such a test is impractical as things stand at the moment, and there is no practical way of performing the rest before the unit enters passenger service, could another way be found. For example, have a duplicate test button mounted in a more accessible place. And use a mirror or other suitable tool to view one of the pipes to see if sand is ejected.
It's likely to be difficult to modify existing units to provide more comprehensive indications to drivers / self checking / self diagnostics to pick up electrical problems. But this could be a requirement for new units.
matchmaker
Established Member
I seem to recall that the Bo'ness & Kinniel Railway was used for some low adhesion training a few years ago.
This is largely inaccurate.
Class 158s (and many others) automatically sand during braking when WSP is activated. This was the scenario here. People who have said "I'm a little surprised that an emergency brake application doesn't trigger the emergency sander, especially if the train is in a slide" clearly haven't actually read the report or are familiar with the trains as the operation of the automatic sander is stated in para. 68.
The TfW 158s have two sanding systems, with the automatic system being complimented with an emergency one shot system. Other operators of class 158s have removed the emergency one-shot sanders. The driver did not operate the one-shot sander (para 82).
So this is not an "unrevealed" failure but a case of the driver not deploying the tools provided. The root cause of this needs to be understood by the investigation.
millemille
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It's not difficult at all, when compared to many other modifications previously implemented, to retrofit a sand flow detections system to existing trains. Proven technology exists and has been in use in mainland Europe for over a decade.
Expect to see this happening in the UK, both as a stand alone upgrade and as part of whole sanding system upgrades, over the next couple of years.
If you're going to sub-quote me, please at least do so directly.
I have read the report, and I fear you're misunderstanding the point being made.
The problem with that approach is that any other train in the area will – or should – immediately come to a stand. Sometimes, that'll make things worse, e.g. if it's just about to clear a junction ahead of the runaway but instead ends up being stopped across it (with the emergency brake often needing to time out after being applied). It's not an enviable position for anyone to find themselves in, but I'd consider an urgent call to the signaller might be preferable in some cases and I certainly wouldn't want it to be mandated one way or the other.
You wouldn't want the one shot emergency sander to work like this though, because the automatic sander already does work like this, but mainly because of the fact that once deployed, the unit is out of service until recharged.
There have been many times where I have made an emergency brake application and the wheels have slid, but the train still decelerated sufficiently, mainly because of the auto sander.
But even if there was no auto sander, I still wouldn't have wanted the one shot to deploy in this way, because there will be many more situations where it would be undesirable for it to operate when sliding in emergency braking than there would be situations where it would be desirable.
When a driver recieves a Railway Emergency Call, the immediate action is to place the brakes in emergency and stop the train. There would be no point in wasting the one shot if you're on a bit of plain double line, recieving a REC about a problem miles away, or even behind you, even if the train does slide when you put it in emergency. Obviously, in this case it would have been desirable for it to operate, but there would have been no way for the system to "know" that, which is why it makes more sense for it to be manually operated. The automatic sander should have been sufficient, if only the pipes weren't blocked.
Should the driver have operated the one shot? Probably, but there may well be a very good reason why it wasn't operated. Maybe the driver tried to, but the button didn't work? The interim report doesn't delve into the reasons why, well have to wait for the final report.
bramling
Veteran Member
Could it have ended because the driver realised that the priority was now to exit the cab? It seems the driver was fully aware that a collision was likely.
Excellent points (from experience) well made. Thanks
I wasn't sure how common an emergency brake application was.
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I mean it's not an every day occurrence, but there are many occasions when an emergency brake application is required. When a REC is received for one, but also for a myriad of other reasons, such as a signalling irregularity (an example of which would be a signal reverting danger), trespassers or obstructions on the line, an ADD activation (Automatic Dropping Device, that drops the pantograph if it hits an obstruction on the overhead line), running over a track defect, any number of train faults, etc etcFair points (from experience) well made. Thanks
I wasn't sure how common an emergency brake application was.
Indeed; I was suggesting the trigger be emergency brake and WSP activity for the one shot, rather than every emergency brake application. But that still might be an unacceptably high false-positive rate.
Yes, but unless the rails are very dry, an emergency brake application will almost always trigger at least a small amount of wheel slide, resulting in WSP activity. It only takes a little bit of moisture on the rail, or even in the air as fog or mist to cause wheel slide under such heavy braking. Which is adequately dealt with by the automatic sanding system.
edwin_m
Veteran Member
If the continuous sander is working correctly then application of the emergency one-shot as well may result in too much sand on the rails. I don't know if it still applies but originally special precautions were needed due to compromised train detection after the one-shot was used. If it still does then it would add this to the list of problems with triggering the one-shot from the emergency brake.
voyagerdude220
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Fair point. Yes that could certainly make things much worse in some scenarios.