Incident at Talerddig, Wales - 21/10/2024

[Lurcheroo]

will not state 'during leaf-fall season, test the rail adhesion levels by braking harder initially and then take your chances by easing off on the brake and if you miss the station, then fair enough'.

Lol ! Thanks for the chuckle.

Interestingly the braking instructions I have for a 158 during low adhesion do not state ‘lighter and earlier’ they state earlier but still in step2.

I have also been taught to do a ‘running brake test’ suitably early (which coincides with the braking instruction) but o test the rail head. If adhesion is good then you can back off and run in slower, if she starts to go then you can leave it in Step2 and select step3 or emergency as necessary. It explicitly states to resis the temptation to empower the braking step or release the brake and instead allow the WSP to do its job.

I know a few drivers who swear by using an early Step1 and let it come off slowly for a long time and I know some who swear by feathering the brake.
I always enjoyed physics and studied engineering, if the friction coefficient is enough to sustain a Step1 application but not a 2 then braking early enough to do it in 1 seems the most controlled way to do it. The concern seems to be around prolonged use of Step1 and Brake fade.

 

[CC 72100]

I know a few drivers who swear by using an early Step1 and let it come off slowly for a long time and I know some who swear by feathering the brake.
I always enjoyed physics and studied engineering, if the friction coefficient is enough to sustain a Step1 application but not a 2 then braking early enough to do it in 1 seems the most controlled way to do it. The concern seems to be around prolonged use of Step1 and Brake fade.

Genuine question - have you ever experienced brake fade on a 158?

I've never experienced 158 brake fade (158 Step 1 is weak, but consistently weak!) and I say this as someone who is very much a predominantly step 1 driver in 158s (shoot me now!) at this time of year.

My logic is basically as you describe - keep it in the sweet spot where I'm applying enough force to slow the train, but not too much as to end up in a slide.

Other disc braked traction does suffer from low speed (30 and under) brake fade, but it's never something I've noticed with 158s.

 

[chuff chuff]

On scotrail at least we moved from the earlier/lighter several years back to you MUST use step two as your initial brake.

 

[jfowkes]

This is only a semi-related question, but how much sand is there in the hoppers, and how many brake applications can it last for?

 

[edwin_m]

If a driver 'brakes a bit harder' then the train will slide, and the driver may not be able to regain control in order to stop at the station. You seem to be claiming that the driver, once sliding can then use a lesser/lighter step of the brake to regain control which whilst not always even possible, is almost certainly not in accordance with any TOC's driving instructions which, unsurprisingly, will not state 'during leaf-fall season, test the rail adhesion levels by braking harder initially and then take your chances by easing off on the brake and if you miss the station, then fair enough'.

It's always possible to release and reapply the brakes with a modern multiple unit, unlike a straight air brake, and @Lurcheroo seems to be suggesting something similar. I recognised in the earlier post that what I'm suggesting isn't in accordance with policy - I think there's an argument that the policy of treating station overruns as equivalent to SPADs actually reduces safety.

 

[172007]

Has anyone mentioned line side traction gel allocator, these make a difference. It isn't mentioned if one was provided at Talerddig so assume not and wonder if one had of been there if it would have made a difference, possibly not as not enough train ls I suspect.

 

[Lurcheroo]

Genuine question - have you ever experienced brake fade on a 158?

I've never experienced 158 brake fade (158 Step 1 is weak, but consistently weak!) and I say this as someone who is very much a predominantly step 1 driver in 158s (shoot me now!) at this time of year.

My logic is basically as you describe - keep it in the sweet spot where I'm applying enough force to slow the train, but not too much as to end up in a slide.

Other disc braked traction does suffer from low speed (30 and under) brake fade, but it's never something I've noticed with 158s.

I haven’t.
I’ve had it in a car but that’s it.
Brake fade occurs when the brakes get hot enough they pass the ‘kneepoint’ and friction is drastically reduced.

By braking light and early then heat will vent off over that longer period of time so shouldn’t be an issue.

Of the few recent station over runs I know of and have chatted with the drivers about, they all began with a brake step2 application.

I would love to know what the logic and reason for the instruction of step2 but early comes from.

Interesting about other disc braked trains step1 getting worse below 30mph.

 

[chuff chuff]

I haven’t, but I’m very new, but I’ve heard no stories either.
I’ve had it in a car but that’s it.
Brake fade occurs when the brakes get hot enough they pass the ‘kneepoint’ and friction is drastically reduced.

By braking light and early then heat will vent off over that longer period of time so shouldn’t be an issue.

Of the few recent station over runs I know of and have chatted with the drivers about, they all began with a brake step2 application.

I would love to know what the logic and reason for the instruction of step2 but early comes from.

Interesting about other disc braked trains step1 getting worse below 30mph.

Been driving them for over thirty years now and I've never noticed brake fade but we were never taught to have them running in step 1 for any length of time indeed the early days it was straight into 3 though that was modified later.
What we were told was disc brake better at high speed and tread brake better at lower speed.

 

[12LDA28C]

It's always possible to release and reapply the brakes with a modern multiple unit, unlike a straight air brake, and @Lurcheroo seems to be suggesting something similar. I recognised in the earlier post that what I'm suggesting isn't in accordance with policy - I think there's an argument that the policy of treating station overruns as equivalent to SPADs actually reduces safety.

Yes of course, but an initial brake application in step 2 will increase the risk of sliding which is exactly what a driver is trying to avoid. I don't know of any TOCs that 'treat station overruns as equivalent to SPaDs' and indeed if a train has slid through a station, as long as the driver has followed the appropriate company instruction with regard to braking during poor railhead conditions then they will be exonerated and the station miss will most likely not even appear on their record.

I would love to know what the logic and reason for the instruction of step2 but early comes from.

Indeed.

 

[millemille]

This is only a semi-related question, but how much sand is there in the hoppers, and how many brake applications can it last for?

Sand hoppers typically hold between 20kg and 60kg of usable sand, depending on the class of rolling stock, so a nominal 2kg/min sand delivery rate will give at least 10 minutes of sanding...

 

[bahnause]

Of the few recent station over runs I know of and have chatted with the drivers about, they all began with a brake step2 application.

Some units only use sand above a certain braking force demand. In these cases, the use of step 2 as initial brake step was a safety recommendation, which was implemented on the basis of several RAIB reports. Maybe not relevant in the Talerddig incident.


Autumn Adhesion Investigation Part 2: Signal LW9 Passed at Danger at Lewes 30 November 2005

110) Southern Railway has modified its Professional Driving Policy to require drivers of all types of rolling stock to make their initial brake application in step 2 rather than step 1 during the autumn low adhesion season. This will ensure that sanding is immediately available if WSP activity is experienced

 

[millemille]

New NIR (4134) out from TfW today, in summary the sander on the leading vehicle of the sliding train has been found with two separate electrical faults, either of which prevented the sander from working automatically when wheel slide occurred. These failures were undetected because the sander test button was down stream of the faults so the operation of the sander via the test button was unaffected.

 

[800Travel]

New NIR (4134) out from TfW today, in summary the sander on the leading vehicle of the sliding train has been found with two separate electrical faults, either of which prevented the sander from working automatically when wheel slide occurred. These failures were undetected because the sander test button was down stream of the faults so the operation of the sander via the test button was unaffected.

What an NIR?

 

[Nottingham59]

New NIR (4134) out from TfW today, in summary the sander on the leading vehicle of the sliding train has been found with two separate electrical faults, either of which prevented the sander from working automatically when wheel slide occurred. These failures were undetected because the sander test button was down stream of the faults so the operation of the sander via the test button was unaffected.

One electrical fault is a misfortune. Two separate faults on the same electrical circuit could be co-incidence, I suppose, or a symptom of something else ....

 

[millemille]

What an NIR?

National Incident Report.

Every duty holder in the UK Railway Undertaking has a responsibility to report any failure or incident or near miss or accident which could affect others in the industry because they use the same, or similar, process or equipment. There is a national database and email alert alert system, run by Serco on behalf of the Railway Safety and Standards Board.

 

[JakeMurphy]

National Incident Report.

Every duty holder in the UK Railway Undertaking has a responsibility to report any failure or incident or near miss or accident which could affect others in the industry because they use the same, or similar, process or equipment. There is a national database and email alert alert system, run by Serco on behalf of the Railway Safety and Standards Board.

Sorry if I have missed anything, but is there any update on the state of these 2 158’s?

 

[aar0]

New NIR (4134) out from TfW today, in summary the sander on the leading vehicle of the sliding train has been found with two separate electrical faults, either of which prevented the sander from working automatically when wheel slide occurred. These failures were undetected because the sander test button was down stream of the faults so the operation of the sander via the test button was unaffected.

How remarkable. So there’s a possibility plenty of 158s which pass the daily test, and through luck haven’t needed to fire the sander, or it’s failure to perform hasn’t been critical. I wonder if the Salisbury 158s sanders were inspected, or if they were too damaged after the crash.

 

[Nottingham59]

How remarkable. So there’s a possibility plenty of 158s which pass the daily test, and through luck haven’t needed to fire the sander, or it’s failure to perform hasn’t been critical. I wonder if the Salisbury 158s sanders were inspected, or if they were too damaged after the crash.

More than a possibility. If the sliding train had just one fault, you'd couldn't say anything about the likelihood of another train having a similar fault. But with two separate and undetected faults being discovered, there's a much greater probability that other 158s under the same maintenance regime will have one or other of these safety-critical issues.

 

[chrisjo]

Sorry if I have missed anything, but is there any update on the state of these 2 158’s?

The 'good' end of 824 was still sticking out of the old steam shed at Mach on 29th December, but I didn't walk up the track to view the other end of the shed where 841 was visible last time I looked on the 1st November.

 

[BigB]

New NIR (4134) out from TfW today, in summary the sander on the leading vehicle of the sliding train has been found with two separate electrical faults, either of which prevented the sander from working automatically when wheel slide occurred. These failures were undetected because the sander test button was down stream of the faults so the operation of the sander via the test button was unaffected.

Daft laddie question, but does this mean that the sanders could have been operated manually from the cab? It's unlikely that a driver would consider doing this if they believed that the automatic system would be operating, but is it something that drivers would be trained to do when a slide occurs?

 

[chrisjo]

The 'good' end of 824 was still sticking out of the old steam shed at Mach on 29th December, but I didn't walk up the track to view the other end of the shed where 841 was visible last time I looked on the 1st November.

I've had a closer look at the photos I took on the 29th December, and it looks to me like I can see through the shed and a bit of what is presumably 841 is also visible behind 824, so basically they haven't moved since they arrived from Talerddig.

 

[Dieseldriver]

Daft laddie question, but does this mean that the sanders could have been operated manually from the cab? It's unlikely that a driver would consider doing this if they believed that the automatic system would be operating, but is it something that drivers would be trained to do when a slide occurs?

With some traction the Driver is only able to manually lay sand when wheelslip occurs under power (sand application being taken care of automatically when wheel slide occurs whilst braking). I can’t speak for the traction involved in this incident though.

 

[BigB]

With some traction the Driver is only able to manually lay sand when wheelslip occurs under power (sand application being taken care of automatically when wheel slide occurs whilst braking). I can’t speak for the traction involved in this incident though.

Thanks - I assume that for a "test" to occur though, it must be possible to operate the sanders whilst stationary or does that just register that it sees the button is pressed?
For much older traction a manual valve would allow steam to be applied, or for heritage diesels air from the compressor (not sure about vacuum only though!)
158s will be far more advanced than this but I imagined that the button opened a solenoid on the air pipe to the sanders thus forcing an air/sand mix. When running, the wheel spin protection (WSP) would actuate the same solenoid until the wheel spin ended?

Apologies if this seems like going down a rabbit hole, I am struggling to see how the test for the damaging system fails to identify a non-operating system!

 

[edwin_m]

Thanks - I assume that for a "test" to occur though, it must be possible to operate the sanders whilst stationary or does that just register that it sees the button is pressed?
For much older traction a manual valve would allow steam to be applied, or for heritage diesels air from the compressor (not sure about vacuum only though!)
158s will be far more advanced than this but I imagined that the button opened a solenoid on the air pipe to the sanders thus forcing an air/sand mix. When running, the wheel spin protection (WSP) would actuate the same solenoid until the wheel spin ended?

Apologies if this seems like going down a rabbit hole, I am struggling to see how the test for the damaging system fails to identify a non-operating system!

I think it means the solenoid and air supply and the connection to the test button are fine, but the part of the circuit that connects it to the WSP has a fault.

The way round this would be to have the test button connect to the WSP and trigger it to actuate the sander in the same way as it does in service, thus proving the whole circuit. But in the case of the 158 the sander was retrofitted, and I suspect modifying an existing WSP to do this might have been tricky.

 

[Belperpete]

The 'good' end of 824 was still sticking out of the old steam shed at Mach on 29th December, but I didn't walk up the track to view the other end of the shed where 841 was visible last time I looked on the 1st November.

When I passed through Mach last weekend, there were two units parked in the shed road, sticking out each end of the shed, with their adjacent ends sheeted over in blue tarpaulin. I take it that these were the same units.

Have the RAIB released them yet?

 

[HamworthyGoods]

When I passed through Mach last weekend, there were two units parked in the shed road, sticking out each end of the shed, with their adjacent ends sheeted over in blue tarpaulin. I take it that these were the same units.

Have the RAIB released them yet?

As one would assume they are most likely going to go for scrap after the investigation is finished there presumably is no hurry to release them?

 

[Belperpete]

Thanks - I assume that for a "test" to occur though, it must be possible to operate the sanders whilst stationary or does that just register that it sees the button is pressed?
Apologies if this seems like going down a rabbit hole, I am struggling to see how the test for the damaging system fails to identify a non-operating system!

It depends on how much of the system it tests. Generally, the further up-stream you go, the more complex it gets. You could, for example, connect the test button in parallel with the WSP output that controls the sanders. But that wouldn't prove that the WSP output was working. Proving that might need you to simulate all the WSP inputs.

I could envisage a situation where the WSP appears to be working correctly, because it correctly controls the traction motors, and the sanders appear to be working correctly when tested manually, but for some reason the WSP fails to operate the sanders.

 

[Harpo]

As one would assume they are most likely going to go for scrap after the investigation is finished there presumably is no hurry to release them?

I would imagine though that Mach depot might want rid of them?? It looks like a seriously compact site.

 

[yorkie]

If anyone would like to discuss the possible fate of the vehicles involved in the collision, please use the following thread:

Can the damaged 158s from Talerdig be reused/reformed?

Moderator note: split from https://www.railforums.co.uk/threads/incident-at-talerddig-wales-21-10-2024.275845/page-14 Could the good ends be added to other 158's to make a 3 car? IIRC the damaged ends on both units are both ends with an accessible toilet.

www.railforums.co.uk

 

[Meerkat]

I think it means the solenoid and air supply and the connection to the test button are fine, but the part of the circuit that connects it to the WSP has a fault.

The way round this would be to have the test button connect to the WSP and trigger it to actuate the sander in the same way as it does in service, thus proving the whole circuit. But in the case of the 158 the sander was retrofitted, and I suspect modifying an existing WSP to do this might have been tricky.

Would you want the sander to actually operate as part of the test - wouldn’t that be an issue in areas where this might happen with sand going places you don’t want it?