Collision and derailment near Salisbury (Fisherton Tunnel) 31/10/21

[seagull]

In any event, even if a RHTT train didn't run, drivers are under instructions to carry out regular brake tests on their journey.

Perhaps at where you work that's true but it's by no means a nationally required standard: regular brake tests are only mandated during snow fall or lying snow being disturbed by trains.

Partly because leaf contamination can change multiple times in the space of yards, let alone miles.

Wisdom and experience does of course dictate that the areas which are known to be bad or potentially hazardous in autumn are treated with more care, braking earlier and lighter.

With 12 seconds between the driver's initial brake and his emergency brake, I would think he was indeed braking in good time given the expected conditions, but sometimes it can be suddenly so much worse than expected there is little that can be done (and what there is, he did).

 

[Moonshot]

Perhaps at where you work that's true but it's by no means a nationally required standard: regular brake tests are only mandated during snow fall or lying snow being disturbed by trains.

Partly because leaf contamination can change multiple times in the space of yards, let alone miles.

Wisdom and experience does of course dictate that the areas which are known to be bad or potentially hazardous in autumn are treated with more care, braking earlier and lighter.

With 12 seconds between the driver's initial brake and his emergency brake, I would think he was indeed braking in good time given the expected conditions, but sometimes it can be suddenly so much worse than expected there is little that can be done (and what there is, he did).

So we can safely say that neither driver was at fault. Train driving standards are very high in the UK, any driver acting in a gung ho fashion would find himself on the wrong end of a p45

 

[bramling]

Perhaps at where you work that's true but it's by no means a nationally required standard: regular brake tests are only mandated during snow fall or lying snow being disturbed by trains.

Partly because leaf contamination can change multiple times in the space of yards, let alone miles.

Wisdom and experience does of course dictate that the areas which are known to be bad or potentially hazardous in autumn are treated with more care, braking earlier and lighter.

With 12 seconds between the driver's initial brake and his emergency brake, I would think he was indeed braking in good time given the expected conditions, but sometimes it can be suddenly so much worse than expected there is little that can be done (and what there is, he did).

One detail which had been unsettling me, was that from the outset it appeared the driver had remained in his cab throughout, and this now appears to have been confirmed. Serious respect for that.

 

[sonic2009]

Apologies if this has already been covered, but what happened to 1F27 (delay went from being 6 minutes to 157 minutes late by time it reached Romsey)

It seemed to go over Tunnel Jcn around 1 minute before 1F30 entered the same section

 

[JN114]

Fair point, why couldn't a berth triggered GSMR broadcast be used then?

Similar points on workload - they take a good 5-10 minutes to set up, while the signaller is also meant to be signalling trains etc. Plus it’s a wide-area tool, not really intended for advising a singular train that they are following another singular train.

I genuinely don’t think, at least within current technology it’s a problem easily solved.

Plus I’m wary of overloading traincrew with too much information, and potentially instilling overconfidence in doing so - as already seen in this thread some of your peers prefer following the RHTT.

Is that diagram note or GSM-R broadcast or popup on C-DAS or whatever - or the lack of one when it should have come - going to subconsciously lure the driver who receives it into driving harder than they otherwise would have?

 

[railfan249]

This may seem a basic question and apologies if it’s already been asked but surely signal SY31 being at red meant there was at least a single yellow before this signal, if not a double yellow proceeding that depending on signalling around that area?

 

[northernbelle]

This may seem a basic question and apologies if it’s already been asked but surely signal SY31 being at red meant there was at least a single yellow before this signal, if not a double yellow proceeding that depending on signalling around that area?

That would be expected, yes. But factors such as the distance between signals, overlap beyond them, distance of the wheelslide event (noting incidents that have seen trains slide over several miles) will all be factors that the RAIB will no doubt be investigating.

 

[theageofthetra]

Similar points on workload - they take a good 5-10 minutes to set up, while the signaller is also meant to be signalling trains etc. Plus it’s a wide-area tool, not really intended for advising a singular train that they are following another singular train.

I genuinely don’t think, at least within current technology it’s a problem easily solved.

Plus I’m wary of overloading traincrew with too much information, and potentially instilling overconfidence in doing so - as already seen in this thread some of your peers prefer following the RHTT.

Is that diagram note or GSM-R broadcast or popup on C-DAS or whatever - or the lack of one when it should have come - going to subconsciously lure the driver who receives it into driving harder than they otherwise would have?

Useful information. A recent chat with a signaller over a broadcast due to a defective banner repeater suggested it required a manager to authorise it and they weren't always available?

 

[wobman]

Even with WSP in full working order, there's still no guarantee that a slide can't happen. It's not a perfect system.

This is so true in low adhesion the WSP isn't a perfect system at all, the contact patch between the wheel and the rail is a very small area.

 

[JN114]

Apologies if this has already been covered, but what happened to 1F27 (delay went from being 6 minutes to 157 minutes late by time it reached Romsey)

It was stopped not far past Tunnel Junction on reciept of the emergency call.

All signalling was knocked out in the area and thus it was trapped amongst all the signalling failures around it; until points and level crossings for several miles ahead could be secured etc.

As response staff were (rightly) dealing with the two collided trains, there was nobody to go out and secure the points for 1F27; hence the considerable delay.

Never ideal to strand a train for 2 and a half hours, but we wouldn’t want to make an already bad situation worse with a secondary incident further down the line.

 

[AdamWW]

This may seem a basic question and apologies if it’s already been asked but surely signal SY31 being at red meant there was at least a single yellow before this signal, if not a double yellow proceeding that depending on signalling around that area?

According to the RAIB report (my bold):
"Preliminary analysis of data downloaded from the On Train Data Recorder (OTDR) fitted to train 1L53 shows that the driver initially applied service braking to slow the train on approach to the caution signal before signal SY31."

 

[JN114]

Useful information. A recent chat with a signaller over a broadcast due to a defective banner repeater suggested it required a manager to authorise it and they weren't always available?

I’m really not sure I’m afraid. It may vary from route to route as well.

 

[MotCO]

Two questions from someone outside the 'rail family':

1. If heavy rain was predicted, would any treatment by the RHTT be washed away by the rain meaning that any treatment would have been ineffective, hence the cancelling of the RHTT train?
2. Given the relatively slow speeds of the trains, what on earth happens on the high speed lines (125 mph) when there is poor railhead adhesion? Do they manage the vegetation better, or are trains liable to slip for a very long way?

 

[Llama]

That's complete rubbish.....it certainly appeared at my depot on Saturday morning just gone.


In any event, even if a RHTT train didn't run, drivers are under instructions to carry out regular brake tests on their journey. It's a rational thing to do in the dark as it's impossible to actually see the condition of the railhead in front of you

Careful making that assumption, at Vic this is the first year that reliable info on RHTTs not running has been posted consistently. At this time of year at foreign depots I always visit the SOP to check their notice cases.

And every year the compliance by our SOP seems to get sloppy towards the end of the leaffall season, it's only just started getting bad and there's still a month to go. It also depends on them receiving the info to post - look in the late notice case now - there are two ESR notices that should have been removed a long time ago, one should have gone in July but it's still there. It doesn't help that we have some inexperienced guards of varying competence as deputy DSMs but that's another issue.

 

[theageofthetra]

Two questions from someone outside the 'rail family':

1. If heavy rain was predicted, would any treatment by the RHTT be washed away by the rain meaning that any treatment would have been ineffective, hence the cancelling of the RHTT train?
2. Given the relatively slow speeds of the trains, what on earth happens on the high speed lines (125 mph) when there is poor railhead adhesion? Do they manage the vegetation better, or are trains liable to slip for a very long way?

As far as I understand it the RHTT these days is just a very high pressure water jet that blasts the railhead contamination away

 

[MOONY]

Would someone explain what the abbreviations HPSS [points] and ERSE [routes] mean please?

 

[800001]

People quite rightly questioning why rhtt was cancelled, but was the rhtt used somewhere else where it may of been deemed more necessary? Conditions where trains collided may of been deemed sufficient enough not to require the treatment, also as several people have previously commented, conditions can change in minutes.


Big respect for driver staying in his seat, and not leaving the Cab prior to collision, I wish him a speedy recovery.

 

[Moonshot]

As far as I understand it the RHTT these days is just a very high pressure water jet that blasts the railhead contamination away

It is......and there are also some trials to have similar equipment fitted to service trains......

 

[theageofthetra]

It is......and there are also some trials to have similar equipment fitted to service trains......

A very good idea.

 

[Bigfoot]

As far as I understand it the RHTT these days is just a very high pressure water jet that blasts the railhead contamination away

Plus a trail of sandite or whatever it is called this week.

 

[Moonshot]

People quite rightly questioning why rhtt was cancelled, but was the rhtt used somewhere else where it may of been deemed more necessary? Conditions where trains collided may of been deemed sufficient enough not to require the treatment, also as several people have previously commented, conditions can change in minutes.


Big respect for driver staying in his seat, and not leaving the Cab prior to collision, I wish him a speedy recovery.

It's not unknown for RHTT runs to be cancelled simply because a failed freight train was in the way. Fair play to the driver, though I wouldn't be surprised if at his age, he now decided to give it up. Clearly a major shock to the system

 

[Llama]

As far as I understand it the RHTT these days is just a very high pressure water jet that blasts the railhead contamination away

Some also lay a bead of sandite on the railhead as they pass, that's been the norm on the RHTTs working out of Springs Branch (so North West circuits) for a few years now.

 

[theageofthetra]

So can someone confirm if either SW or GW issued a notice to their drivers that weekend that the RHTT was not running over that route?

 

[swt_passenger]

Would someone explain what the abbreviations HPSS [points] and ERSE [routes] mean please?

HPSS stands for high performance switch system, a particular manufacturer’s name for its points actuator and back drive. some info here: https://cupdf.com/document/hpsa-in-sleeper.html As mentioned at the time, it’s not actually relevant to this location.

ERSE is electronic route setting equipment, it’s explained in and around post #358. An aspect of the Salisbury signalling installation.

 

[alxndr]

Would someone explain what the abbreviations HPSS [points] and ERSE [routes] mean please?

HPSS is a type of point operating equipment (i.e. the thing that makes the switch blades move). That wasn't what was installed here, from the photographs I'd say it looks like standard clamplocks with mechanical backdrives.

I've added two images of examples, the big yellow kit is HPSS, the other is a standard clamplock.

 

[Dan G]

Not much of an interim report that; I guess it's a bit different in rail world than in aviation. No mention of the speed of either train, nor braking points, though yes, it sounds like the SWR train braked at least approximately in the usual spot (but usual in good rail adhesion conditions?) and didn't get the necessary retardation.

Let's be clear; the 159 should have been able to stop in time, even at this time of year, even if that requires a RHTT pass within x number of previous axle passes and sand in the hoppers.

Still, we'll find out eventually.

 

[jfollows]

This may seem a basic question and apologies if it’s already been asked but surely signal SY31 being at red meant there was at least a single yellow before this signal, if not a double yellow proceeding that depending on signalling around that area?

See post #372 for more information on layout and signalling. #372

 

[Moonshot]

Not much of an interim report that; I guess it's a bit different in rail world than in aviation. No mention of the speed of either train, nor braking points, though yes, it sounds like the SWR train braked at least approximately in the usual spot (but usual in good rail adhesion conditions?) and didn't get the necessary retardation.

Let's be clear; the 159 should have been able to stop in time, even at this time of year, even if that requires a RHTT pass within x number of previous axle passes and sand in the hoppers.

Still, we'll find out eventually.

Slips and slides are very common at this time of year, however the vast majority end up at nothing. Occasionally there will be a station overun.....and at the very extreme, an accident such as this. Laws of physics are very difficult to defeat

 

[millemille]

Even with WSP in full working order, there's still no guarantee that a slide can't happen. It's not a perfect system.

As soon as WSP activity occurs the train's actual deceleration rate is not going to match brake demand made by the driver. The WSP system is releasing and applying the brakes to attempt to let the wheel's rotational speed match the train's speed over ground. How much less the actual deceleration rate is than the brake demand depends on the coefficient of friction of the railhead and the effectiveness of WSP system's algorithm's in regaining control of the wheels.

 

[357]

Which they aren't at weekends.

...and not even during the week at many remote signing on points!