6A11 (Robeston Sidings - Theale Murco) on fire near Llanelli (27/08)

[Bald Rick]

I know this is a busy stretch of line but when this happened (possibly 1998) I'm sure it wasn't closed for weeks on end. Why does it seem than any accident these days take forever to reopen? Look at Eastleigh this year weeks of disruption. I remember back in 1996 severe freight derailment near my town (fortunately no injuries) was opened within a few days.

Selective memory.

Scale of recovery and ease thereof is a significant factor.

 

[Llanigraham]

I know this is a busy stretch of line but when this happened (possibly 1998) I'm sure it wasn't closed for weeks on end. Why does it seem than any accident these days take forever to reopen? Look at Eastleigh this year weeks of disruption. I remember back in 1996 severe freight derailment near my town (fortunately no injuries) was opened within a few days.

Perhaps because the iron ore train didn't cause so much environmental damage?

And since 1996 they have been many changes in Health & Safety rules.

 

[Tom Quinne]

Any update?

I wouldn’t waste your time reading messroom rumours, those who need to know know now. Procedures are in place to stop or at least mitigate the situation happening again.

 

[Steve Harris]

Perhaps because the iron ore train didn't cause so much environmental damage?

And since 1996 they have been many changes in Health & Safety rules.

Indeed. I was going to say more Risk Assessments (which is on the same theme).

 

[2HAP]

RAIB have released an update.

[Withdrawn] Derailment and fire involving a tanker train at Llangennech - updated 21/09/2020

Investigation into the derailment and fire involving a tanker train at Llangennech, Carmarthenshire, 26 August 2020.

www.gov.uk

RAIB’s preliminary examination found that, although all the wheels of the train were probably rotating freely when the train left Robeston, at some point during the journey the brakes on all wheels of the third wagon of the train had become applied, and remained so until the derailment. While three of the four axles of this wagon continued to turn, although their brakes were dragging, the leading axle ceased to rotate altogether, and consequently a flat spot around 230 mm long developed on each of the wheels on this axle. There was a substantial ‘false flange’ (a raised lip on the outer side of the wheel tread) associated with these flat spots.

 

[Tomos y Tanc]

RAIB have released an update.

[Withdrawn] Derailment and fire involving a tanker train at Llangennech - updated 21/09/2020

Investigation into the derailment and fire involving a tanker train at Llangennech, Carmarthenshire, 26 August 2020.

www.gov.uk

That sounds very like what happened with the same train on the same stretch of line in 2017.

 

[father_jack]

The whisperer may get a bit embarrassed.

Let's wait for what the RAIB enquiry into other possible reasons throws up.

Whisperer shouldn't be all that embarrassed in the end, the wheels weren't going round for whatever reason !!!

 

[Clarence Yard]

But it may not have been the handbrake wot caused it, guv’nor!

 

[Don Steedy]

It wasn’t the handbrake. An NIR was raised last week for TEA wagons funnily enough...

 

[2HAP]

It wasn’t the handbrake. An NIR was raised last week for TEA wagons funnily enough...

OK, I know that TEA is a wagon designation, not a wagon carrying tea, but I thought that NIR meant Northern Ireland Railways. Please elucidate.

 

[Don Steedy]

OK, I know that TEA is a wagon designation, not a wagon carrying tea, but I thought that NIR meant Northern Ireland Railways. Please elucidate.

National Incident Report. It’s how TOCs, FOCs and railway suppliers communicate high-risk rolling stock defects and failures with each other

 

[Dunfanaghy Rd]

Whisperer shouldn't be all that embarrassed in the end, the wheels weren't going round for whatever reason !!!

Handbrake only works on one bogie, so you must whisper back to enquire the reason that a 3rd wheel set was dragging.
Pat

 

[father_jack]

Handbrake only works on one bogie, so you must whisper back to enquire the reason that a 3rd wheel set was dragging.
Pat

Agreed but in the heat of the moment, if you pardon the pun.

 

[big all]

do the tanks have one cylinder interlinked by rods and a large release spring like they used to or 2 cylinders not connected between bogies ??

 

[edwin_m]

do the tanks have one cylinder interlinked by rods and a large release spring like they used to or 2 cylinders not connected between bogies ??

Images in #137 show some of it, albeit damaged, including wagon 2 which caused the derailment. As far as I can tell there is one cylinder operating both bogies (the other one being the reservoir) but it's possible there was a second one that has been torn off in the accident.

 

[big all]

Images in #137 show some of it, albeit damaged, including wagon 2 which caused the derailment. As far as I can tell there is one cylinder operating both bogies (the other one being the reservoir) but it's possible there was a second one that has been torn off in the accident.

Thanks i see the brake cylinder now
as all brakes are interlinked if you have a lightly rubbing brake and an over adjusted[to tight ]linkage although very small expansion off the brake blocks and wheels as heat builds up will tighten up the linkage unless there is enough slack elsewhere to accommodate the expansion
Now not suggestion a cause just pointing out there is a direct connection [linkage] between bogies so could be an explanation for the third axle away from the handbrake being involved ??

 

[Dunfanaghy Rd]

do the tanks have one cylinder interlinked by rods and a large release spring like they used to or 2 cylinders not connected between bogies ??

All the TEAs I ever worked with (various Holybourne pools), and indeed, almost every other bogie vehicle I can call to mind have 2 brake cylinders (1 to each bogie). Seacow / Sealion are an exception, and the rigging is a nightmare (as the wagon group at the MHR are discovering!). Apart from the embuggerance of the extra rigging to allow a single cylinder, 2 cylinders allow the weighing valve / variable load valve to set the air pressures in each cylinder to suit the actual loading on each bogie. Handbrakes are usually just the one (although the disc-braked BDAs had 2) which is enough.
Pat

 

[doningtonphil]

Is it not the case that the bogie and braking arrangement on the wagon that had the fault was different to the ones seen in the photos?
The brake actuators are mounted on the bogie rather than the brake cylinder arrangement.

The conclusion you would be tempted to arrive at , looking at the NIR, is that the incident was caused by 4 nuts undoing themselves sufficiently for an o ring to blow out from between a valve and its manifold.

So the NIR recommends that all wagons of that type be checked for the tightness of the bolts. Surely the implications are much more widespread than that, as EVERY brake valve on wagons is only held on by up to 4 nuts on studs, so surely every wagon faces the same risk.

Which leads to the question how do 4 nuts undo themselves so readily?

 

[Don Steedy]

Is it not the case that the bogie and braking arrangement on the wagon that had the fault was different to the ones seen in the photos?
The brake actuators are mounted on the bogie rather than the brake cylinder arrangement.

The conclusion you would be tempted to arrive at , looking at the NIR, is that the incident was caused by 4 nuts undoing themselves sufficiently for an o ring to blow out from between a valve and its manifold.

So the NIR recommends that all wagons of that type be checked for the tightness of the bolts. Surely the implications are much more widespread than that, as EVERY brake valve on wagons is only held on by up to 4 nuts on studs, so surely every wagon faces the same risk.

Which leads to the question how do 4 nuts undo themselves so readily?

I’d say they almost certainly weren’t done up correctly in the first place

 

[edwin_m]

Is it not the case that the bogie and braking arrangement on the wagon that had the fault was different to the ones seen in the photos?

As I posted in #195, one of the photos shows the remains of the brake gear of the wagon that did cause the derailment.

 

[4069]

The wagon that the emergency services labelled 1 was the one that derailed first and whose wheels were locked. The relevant parts of its brake gear are not shown in any of those photos.

 

[1955LR]

RAIB issued safety advise 02/2020 https://www.gov.uk/government/publi...r-wagons-that-primarily-carry-dangerous-goods

1. Safety issue
Suitable processes, facilities, tools and equipment may not be in place to prevent safety critical system components becoming unsafe due to insecure fastenings.

2. Safety advice
Entities in Charge of Maintenance (ECMs) should review their system of inspection and maintenance for wagons that primarily carry dangerous goods, to ensure that they have appropriate arrangements in place to manage the safety risk associated with malfunction of the braking system. This should include an assessment of the adequacy of:

• facilities, tools and equipment at all maintenance locations
• systems for assuring the competence of those involved
• management systems and instructions for assuring the quality of work undertaken
• methods for initial and ongoing assurance of the security of fastenings
• processes for the identification and tracking of safety critical components.

This assessment should take into account the particular hazards associated with conveying dangerous goods

3. Issued to:
ECMs responsible for the maintenance of wagons which primarily convey dangerous goods in the UK.

4. Background
At about 23:15 hrs on 26 August 2020, train 6A11, the 21:52 hrs freight service from Robeston (Milford Haven) to Theale, conveying 25 tank wagons, each containing up to 75.5 tonnes of diesel or gas oil, derailed on the ‘Up District’ line near Llangennech, in Carmarthenshire. The derailment and the subsequent damage to the wagons resulted in a significant spillage of fuel and a major fire. Subsequent examination of the site revealed that a total of 10 wagons (positioned 3rd to 12th in the train) had derailed, and that around 330,000 litres of fuel had been spilt.

RAIB’s preliminary examination found that, although all the wheels of the train were probably rotating freely when the train left Robeston, at some point during the journey the brakes on all wheels of the third wagon of the train had become applied, and remained so until the derailment. Although their brakes were dragging, three of the four axles of this wagon continued to turn. At some point in the journey the leading axle ceased to rotate altogether, as evidenced by a CCTV camera located at Pen-y-Bedd level crossing (12 miles (19 km) from Morlais Junction), and marks on the railhead.

CCTV image showing the third wagon passing Pen-y-Bedd level crossing

The locking of the leading axle of the third wagon caused the development of a flat spot around 230 mm long on both of the wheels on this axle. This in turn created substantial ‘false flanges’ (raised lips on the outer side of the wheel treads). When the train reached the crossover at Morlais Junction, travelling at about 30 mph (48 km/h), the false flange on the right-hand wheel caught on the converging stock rail and distorted the track, leading to derailment of both wheels. Around 100 metres further on, the partly derailed wagon encountered facing points set to route the train to the right. The locomotive and the two leading wagons went to the right and the derailed third wagon went straight ahead. The third wagon turned over onto its right-hand side and became detached from the wagon in front of it. This caused the points and the track beyond them to be destroyed, and derailment of another nine wagons followed.

Examination of the brake group on the third wagon (TEA wagon GERS89005) found that the relay valve was loose on the pipe bracket. A sealing ring from one of the ports in the mating face had migrated to a position where it lodged between two other ports, distorted the sealing rings of those ports, and probably created a route for air to pass directly from the auxiliary reservoir to the wagon brake cylinder. This would have had the effect of applying the brakes on the wagon, producing the result described above.

Brake group on TEA wagon

The ECM for the wagon was unable to identify with any degree of certainty where and when the fastenings of the relay valve had last been disturbed. However, this may have taken place during routine repairs in the sidings at Robeston terminal or during scheduled maintenance elsewhere. There was no record of any check on the tightness of the fastenings ever having been made, and no process requiring such checks or provision of any measures, such as witness markings, which would have indicated that fastenings were becoming loose.

 

[aar0]

That seems pretty damming.

 

[doningtonphil]

One os the improvements to be considered is:

• methods for initial and ongoing assurance of the security of fastenings

The bulletin has been issued for wagons that primarily carry dangerous goods, does that mean that opertors of all other rail vehicles have sufficient methods/practices in place to regularly check that the bolts securing brake equipment are as tight as they should be? Should this instruction not be to every vehicle operator?

 

[doningtonphil]

I think it is a little bit scary that when you read the NIR about this incident, the comments section is full of comments such as "not relevant to xxxxxx as we do not operate this type of vehicle" or similar. In reality I noted that some of them are operators of vehicles with bolt on distributors with O ring selaed manifolds, so this should be ver relevant to them.

Also, how common is it for a vehicle operator to have a process that includes the regular checking of he swcurity of bolted on brake equipment? I would suggest not very common at all

 

[PHILIPE]

Swansea District Line now re-open with freights running through and Heart of Wales Line passengers resume Monday up to Llanwrtyd from the south with the COVID reduced Timetable. Not back to normal yet though as trains at the northern end only running between Shrewsbury and Knighton because Network Rail decide to take a two week possession.

 

[ChiefPlanner]

Swansea District Line now re-open with freights running through and Heart of Wales Line passengers resume Monday up to Llanwrtyd from the south with the COVID reduced Timetable. Not back to normal yet though as trains at the northern end only running between Shrewsbury and Knighton because Network Rail decide to take a two week possession.

Very well planned then - ? - or is it being done in advance of Easter and the possibility of some tourist business if Drakeford can be believed.

Not that there hasn't been much opportunity of late.

 

[Cowley]

Thread reopened to discuss RAIB report:

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1045465/R012022_220113_Llangennech.pdf

 

[2HAP]

Thanks,@Cowley for spotting I'd requested the wrong thread to be reopened and sorting it out.

The RAIB report shows a woeful lack of oversight of maintenance and failure to learn from previous incidents.

 

[Cowley]

Thanks,@Cowley for spotting I'd requested the wrong thread to be reopened and sorting it out.

It was actually @GB that helped me find my way out of that dead end.