Incident at Talerddig, Wales - 21/10/2024

[skyhigh]

This isn’t mentioned in the report.

Because it's not a full report. It's just an update.

 

[Lurcheroo]

Indeed, that is possible. However that would be rather less than ideal, particularly at this time of year.

It absolutely would be! Another hole lined up in the ‘swiss cheese’ leading to a a serious incident kind of less than ideal in my opinion.

Our off train Autumn brief days have discussed doing an RBT well before the usual shut off point in leaf fall for all stations or known stopping points to test the rail head. This isn’t mentioned in the report. Wonder what TFW policy/training is for leaf fall driving?

In regards to this part of the update from the RAIB:

Initial analysis of data from the on-train data recorder (OTDR) fitted to train 1J25 shows that the driver applied service braking to slow the train as it neared the loop at Talerddig. Around 40 seconds after the first service brake application, the OTDR records an emergency brake demand being made. This emergency brake demand remained in place until the collision. OTDR data shows that wheel slide started during service braking and was constant during emergency braking.

I think no autumn driving policy was going to prevent this (I appreciate that isn’t what your trying to say), 40 seconds of braking before an emergency braking application was initiated, which if it wasn’t by the driver, the ERTMS system would have done so as soon as it determined that there was insufficient distance to stop the train before the block marker based on the current speed.

 

[InkyScrolls]

How many other single lines having passing loops where the driver is permitted to enter at over 30mph and then enters a known low adhesion area on a very step falling gradient ?

I know of one on my routes, at Springs Jct. (near Guiseley); not technically a loop but the effect is the same. (Same gradient as at Talerddig, and 50 mph PSR).

 

[Llanigraham]

One of the major problems with fitting trap points at the western end of Talerddig loop is where the unit would likely end up.

 

[ainsworth74]

One of the major problems with fitting trap points at the western end of Talerddig loop is where the unit would likely end up.

Quite. If you fit trap points you need to be very very certain that deliberately derailing a passenger carrying train is a better option than a potential collision. That's quite a call to make...

 

[Lurcheroo]

I know of one on my routes, at Springs Jct. (near Guiseley); not technically a loop but the effect is the same. (Same gradient as at Talerddig, and 50 mph PSR).

If you slid past would it potentially be towards oncoming trains ? I’m not familiar with the area.

One of the major problems with fitting trap points at the western end of Talerddig loop is where the unit would likely end up.

That’s is very true, the loops ends next to a private dwelling on the side in which the train would be derailed.

Quite. If you fit trap points you need to be very very certain that deliberately derailing a passenger carrying train is a better option than a potential collision. That's quite a call to make...

Certainly is a tough call, perhaps (if space was available) then it could be a length of track with some kind of arresting system.

The space is definitely not there in this case.

 

[Annetts key]

If you’re happy to spend the money to fit them at every junction, passing loop on single lines, entrance to single lines in the UK.

Network Rail.actually removes catch and trap points when they can on passenger lines now that all regular traffic has continuous fitted braking systems. Trap points (to divert an uncontrolled movement into the ballast / cess) are now mostly limited to freight lines (at the junction approaching a passenger or main line) and freight sidings that exit on to a passenger or main line.

 

[AndrewE]

Network Rail.actually removes catch and trap points when they can on passenger lines now that all regular traffic has continuous fitted braking systems. Trap points (to divert an uncontrolled movement into the ballast / cess) are now mostly limited to freight lines (at the junction approaching a passenger or main line) and freight sidings that exit on to a passenger or main line.

Wasn't this the cause of the collision at Winsford Junction when a northbound pacer on the slow line over-ran into the path of an express? (https://en.wikipedia.org/wiki/1999_Winsford_railway_accident)
You have to make a judgement on whether a crash will cost more than installing trap points and an arrestor system - the multiple friction retarders and buffers that we see in bay platforms etc. look robust and cheap enough - I know what my answer would be!

 

[RailwayRookie]

Forgive the minor divergence from the subject, but still on topic I suppose..

When ERTMS becomes aware a block marker is likely to be overshot or is overshot, does it do anything to trains on conflicting routes?
As in would it put the emergency brakes on the 'non offending' train to reduce the collision forces?

 

[Bald Rick]

You have to make a judgement on whether a crash will cost more than installing trap points and an arrestor system - the multiple friction retarders and buffers that we see in bay platforms etc. look robust and cheap enough - I know what my answer would be!

It’s a much more complex decision than that.

You are judging the lifetime certainty of the costs of trap points (and anything else required), plus the safety risk of them being in place (eg the probability and consequences of even a minor overshoot; the probability and consequences of the points failing, the safety risk of those required to maintain them, etc)

vs

the very remote probability and potentially high consequences of an overshoot leading to a collision, given the mitigations and procedures put in place to prevent such an occurence.


This will have been considered in detail by operations and risk professionals. And I know what my answer would be.

 

[InkyScrolls]

If you slid past would it potentially be towards oncoming trains? I’m not familiar with the area.

You would, yes.

 

[Parham Wood]

It seems that after normal braking was insufficient to slow the train enough emergency braking was applied until the collision. I seem to recall that repeated braking may be more efficient in slides that continuous braking. If the ERTMS can override braking (reading a comment above) and apply the emergency brake does this mean that the driver cannot override this? If the rail adhesion was too low to enable the train wheels to adhere then I assume any type of braking would not stop the train particularly as sanding was not working. Perhaps also the driver applied emergency brake and then left the cab when the collision was unavoidable.

 

[30907]

Network Rail.actually removes catch and trap points when they can on passenger lines now that all regular traffic has continuous fitted braking systems. Trap points (to divert an uncontrolled movement into the ballast / cess) are now mostly limited to freight lines (at the junction approaching a passenger or main line) and freight sidings that exit on to a passenger or main line.

On single line crossing loops they were never standard practice AFAIK, but the first train to arrive would IIRC be severely checked at the inner home before drawing up to the starter.

 

[ainsworth74]

One thought that occurs, and I presume the RAIB will investigate or at least perhaps provide an explanation for, is that this slide must have taken place over quite a period of time. We know that the train was in service braking for around 40 seconds before being put into emergency, it travelled the length of the loop (I think around 500m or so?), then we know it travelled another 900m before actually impacting the Shrewbury bound train. Whilst we don't know the exact speed profile (how fast was it going by the time emergency was kicked in, how much more speed did it lose after that point and the collision) it would seem that that must have taken maybe 60 seconds or so? At around 70kmh (well above the top bound for the impact speed) it would have taken 70 seconds to cover the 1,400m of the loop and the the point of impact.

I wonder if there was a Railway Emergency Call made from the incident train during the slide? That would surely have caused the Shrewsbury train to stop (assuming it didn't also go into a slide!) and perhaps bought more time for the incident train to come to a stand without impacting it?

Perhaps an interesting one to see what transpired when the report comes out!

 

[hexagon789]

I seem to recall that repeated braking may be more efficient in slides that continuous braking.

This is exactly what the WSP system does, repeatedly 'pulsate' the brake in a bid to modulate the slide by getting the wheels rotating again. The newest systems tend to be more effective than those fitted when the 158s were new, but they in turn were much more effective than the systems fitted to the earliest disc-braked stock.

 

[43096]

This is exactly what the WSP system does, repeatedly 'pulsate' the brake in a bid to modulate the slide by getting the wheels rotating again. The newest systems tend to be more effective than those fitted when the 158s were new, but they in turn were much more effective than the systems fitted to the earliest disc-braked stock.

The question might also be legitimately asked why 1980s generation stock hasn't been retro-fitted with new WSP equipment in the last 20 years or so, in the same way that all the HST operators (except FGW/GWR and ScotRail) have done?

 

[matchmaker]

On single line crossing loops they were never standard practice AFAIK, but the first train to arrive would IIRC be severely checked at the inner home before drawing up to the starter.

At Carrbridge on the HML there were a set of run off points which were situated at the entrance to the up (south facing) loop. They were installed in 1940 after a northbound wagon train ran back from Slochd Summit following a coupling breakage. The guard couldn't stop them and they collided head on with a northbound service at Aviemore. I think the driver and fireman of the pilot loco died.

In January 2010 a 66 and 10 HKA container flats suffered partial brake failure on the descent south from Slochd, partly due to snow getting into the brake mechanism of the wagons, and was derailed at the run off points. Minor injuries only to the loco crew.

 

[ThirteenArches]

If I read earlier information correctly, there is a siding which continues from the loop at the downhill (Aberystwith) end. While just diverting the train into that would quite possibly have ended up with wreckage all over the track and a worse collision than actually happened, had the siding been fitted with a sand drag, could it have stopped the train from 35kph within its length? If not, how much longer would it need to be? Or are more sophisticated retarders, deployable from within the loop, available these days which would have stopped the train?

 

[Wilts Wanderer]

One point I’m interested to clarify - it has been stated that the RHTT ran approx 24hrs before the accident. However it’s also been said that ERTMS will always route the first train to arrive at Talerddig into the loop, so that the second train can pass on what is nominally now the ’through line.’ What happens when there is no cross taking place - and does the RHTT routinely cross anything? If not, does this possibly mean that the loop was not getting treated regularly? Or will NR be manually ensuring that the RHTT runs through one line in the down, and the other in the up direction.

 

[Railsigns]

At Carrbridge on the HML there are a set of run off points which are situated at the entrance to the up (south facing) loop.

They've been removed.

 

[12LDA28C]

I wonder if there was a Railway Emergency Call made from the incident train during the slide? That would surely have caused the Shrewsbury train to stop (assuming it didn't also go into a slide!) and perhaps bought more time for the incident train to come to a stand without impacting it?

I understand the Emergency Call was only made from 1J25 once the collision had occurred although the Signaller had already made contact with the other train as soon as it had become apparent a SPaD had occurred.

 

[skyhigh]

It seems that after normal braking was insufficient to slow the train enough emergency braking was applied until the collision. I seem to recall that repeated braking may be more efficient in slides that continuous braking.

I don't know what TfW driver instructions are, but for us with WSP fitted stock if you encounter a full slide you must not attempt to regain rotation, you just stick it in emergency and wait until it stops.

 

[Llanigraham]

One point I’m interested to clarify - it has been stated that the RHTT ran approx 24hrs before the accident. However it’s also been said that ERTMS will always route the first train to arrive at Talerddig into the loop, so that the second train can pass on what is nominally now the ’through line.’ What happens when there is no cross taking place - and does the RHTT routinely cross anything? If not, does this possibly mean that the loop was not getting treated regularly? Or will NR be manually ensuring that the RHTT runs through one line in the down, and the other in the up direction.

My understanding is that the RHTT treats one side of the loop going in one direction and the other side on the return.
The RHTT does not cross another train, but goes DOWN after the last train from Salop.

 

[IrishDave]

If I read earlier information correctly, there is a siding which continues from the loop at the downhill (Aberystwith) end.

No, the siding continues from the loop at the Machynlleth Shrewsbury end. So it could not have been used in this case as it points the wrong way.

 

[edwin_m]

No, the siding continues from the loop at the Machynlleth end. So it could not have been used in this case as it points the wrong way.

Machynlleth and Aberystwyth are both in the same direction from Talerddig.

 

[starlight73]

The reason the siding wasn’t used was covered in this post (click on it to see the full post);

The Up Refuge Siding (to give the run-off siding its proper name) would only be relevant as an overrun if the trains were crossing under left-hand running; in this case, the trains were planned, and signalled, to cross under right-hand running.

i think @ThirteenArches was referring to whether a siding of that length would’ve been effective at stopping a train in general

 

[zwk500]

If I read earlier information correctly, there is a siding which continues from the loop at the downhill (Aberystwith) end.

The siding is at the other end of the loop.

While just diverting the train into that would quite possibly have ended up with wreckage all over the track and a worse collision than actually happened, had the siding been fitted with a sand drag, could it have stopped the train from 35kph within its length? If not, how much longer would it need to be? Or are more sophisticated retarders, deployable from within the loop, available these days which would have stopped the train?

These are questions best answered by an investigation or inquiry, tbh.

 

[Railsigns]

If I read earlier information correctly, there is a siding which continues from the loop at the downhill (Aberystwith) end.

Since Talerddig loop is situated on a summit, both ends are the downhill end.

 

[IrishDave]

Machynlleth and Aberystwyth are both in the same direction from Talerddig.

Sorry, wrote Machynlleth when I meant Shrewsbury! Corrected.

 

[chuff chuff]

I seem to recall that repeated braking may be more efficient in slides that continuous braking.

This is exactly what the WSP system does, repeatedly 'pulsate' the brake in a bid to modulate the slide by getting the wheels rotating again. The newest systems tend to be more effective than those fitted when the 158s were new, but they in turn were much more effective than the systems fitted to the earliest disc-braked stock.

I don't know what TfW driver instructions are, but for us with WSP fitted stock if you encounter a full slide you must not attempt to regain rotation, you just stick it in emergency and wait until it stops.

Whilst the current advice (scotrail) if you think you are not going to stop at the correct spot to put into emergency and leave it which I have done I have also,in the past including the last couple of weeks when gone into a slide and the speedo reading zero even with the brakes released is to give just a little bit of power to get the wheels turning again then to start braking again. This was not done on approach to a station stop or danger signal but when braking for reduction in line speed.