Incident at Chalfont & Latimer (21/06/20)

[dmncf]

Rarely. I think I had 3 occasions when I was front tripped in 25 years of driving, actually rear tripped more often than front. usually, excluding spads the only time the system had to be overridden is following a signal failure. Often when it happens it then affects every train until what ever is causing the issue is sorted so it is only a surprise to the first driver to be affected and a following train will be asked to check the track for obstructions.

Thanks for this insight. It does highlight how wrong it is for the first driver to be tripped and not report what happened, because instead of the following driver being asked to check the track for obstructions, the following driver is none the wiser and probably gets tripped too.

 

[bramling]

Thanks for this insight. It does highlight how wrong it is for the first driver to be tripped and not report what happened, because instead of the following driver being asked to check the track for obstructions, the following driver is none the wiser and probably gets tripped too.

I suspect part of the underlying issue is that procedures still hark back to the days when communication couldn't be assured. The "connect" radio system on LU is pretty reliable, however before that it wasn't uncommon to not be able to get in touch with anyone. Signal post telephones only really existed in semi-automatic areas.

In those days you wouldn't want a massive delay caused by a driver being tripped on a football not being able to report it before moving, so instead the train would continue and the incident be reported to station staff at the next station. If the following train got tripped then so be it.

There's certainly a case for tightening the wording of the procedures on this. One wonders if there's a cultural dimension too, with signals, trainstops and tripcocks generally being on their way out on LU.

 

[matt_world2004]

I suspect part of the underlying issue is that procedures still hark back to the days when communication couldn't be assured. The "connect" radio system on LU is pretty reliable, however before that it wasn't uncommon to not be able to get in touch with anyone. Signal post telephones only really existed in semi-automatic areas.

In those days you wouldn't want a massive delay caused by a driver being tripped on a football not being able to report it before moving, so instead the train would continue and the incident be reported to station staff at the next station. If the following train got tripped then so be it.

There's certainly a case for tightening the wording of the procedures on this. One wonders if there's a cultural dimension too, with signals, trainstops and tripcocks generally being on their way out on LU.

Do Chiltern railways staff have connect radios when operating on LU infrastructure

 

[ainsworth74]

Do Chiltern railways staff have connect radios when operating on LU infrastructure

No, they use GSMR to ring LUL Hammersmith Control who will relay information as required between train and LUL signaller.

 

[bramling]

No, they use GSMR to ring LUL Hammersmith Control who will rely information as required between train and LUL signaller.

Anyone with experience of that part of the railway able to comment on whether there's been any reliability issues with that on the Met section?

 

[O L Leigh]

There's nothing wrong with resetting the tripcock, or TPWS. The issue is moving the train without permission from the signaller. Depending on the unit, there may well be some sort of audible alarm sounding, so if you don't reset it first, it can be very difficult to hold a conversation with the signaller.

Well it’s also the case that most NR stock has a time-out on the emergency brake, usually of two minutes, so resetting it doesn’t always immediately give you a brake release. In this instance we are instructed not to wait to reset whatever it was that caused the brake application because if you leave it until last you’ll still be marooned there until the train decides to give you back control over the brake.

 

[bramling]

Well it’s also the case that most NR stock has a time-out on the emergency brake, usually of two minutes, so resetting it doesn’t always immediately give you a brake release. In this instance we are instructed not to wait to reset whatever it was that caused the brake application because if you leave it until last you’ll still be marooned there until the train decides to give you back control over the brake.

This is a bit different, as in the case of LU the timer starts when the tripcock is reset, and the timer is a safety system designed to help ensure drivers don't drive too fast when applying the rule. It's only an aid though, the onus is still on the driver. As I posted elsewhere, LU's rule book does hint at resetting the tripcock being the last thing, but I wouldn't say it's any more specific than that.

It does seem to me a bit of a mismatch has developed over time between LU and Chiltern regarding Chiltern's running over LU, with LU themselves having a slight procedural grey area but one which for their setup isn't really a major problem in practice. On the same score I must admit I was surprised to learn that Chiltern units *don't* have the speed control after tripping system fitted.

SCAT is a bit of a distraction though - the main issue was that the driver reset and carried on, SCAT is only there to enforce a low speed - and its main intention was to stop drivers misjudging their speed and going too fast to stop if they encountered a train ahead, especially in curved Tube tunnels. That this also has an added benefit for a "reset & continue" incident is incidental really.

 

[Taunton]

Given this happened at night on a straight line, by the time the train came to a stand would the station starting signal have been visible at green ahead?

 

[bramling]

Given this happened at night on a straight line, by the time the train came to a stand would the station starting signal have been visible at green ahead?

I believe so, yes. From what I understand the starting signal was certainly showing a clear aspect - either yellow or green.

 

[edwin_m]

I believe so, yes. From what I understand the starting signal was certainly showing a clear aspect - either yellow or green.

It would possibly have been hidden behind the Met train after the Chiltern train went over the crossover, but was presumably visible before that.

 

[O L Leigh]

On the same score I must admit I was surprised to learn that Chiltern units *don't* have the speed control after tripping system fitted.

I’m unsure how a system like that might have been applied to a diesel-hydraulic unit, especially ones with powertrains shared with other classes and operators.

 

[bramling]

It would possibly have been hidden behind the Met train after the Chiltern train went over the crossover, but was presumably visible before that.

This is my understanding. It would almost certainly have been visible when his train came to a stand after being tripped, and would have remained so.

== Doublepost prevention - post automatically merged: 2 Aug 2021 ==

I’m unsure how a system like that might have been applied to a diesel-hydraulic unit, especially ones with powertrains shared with other classes and operators.

Very interesting point. If nothing else you could have a sonalert-type tone in the cab though - the sort of thing which is sufficiently irritating when it goes off that the driver will react accordingly.

 

[Nym]

I’m unsure how a system like that might have been applied to a diesel-hydraulic unit, especially ones with powertrains shared with other classes and operators.

In exactly the same way they're implemented on twin pipe dual braked 1972TS. A massive dump valve and flow cut off valve.

Given that all of Chiltern's fleet have electrically controlled emergency brakes (excluding the locomotives) implementing a SCAT circuit is essentially trivial.

 

[O L Leigh]

OK, so maybe now I’m not sure precisely what this system is or what it does. Is it essentially a speed limiter that runs on a timer after a tripcock activation and reset?

Stopping a Chiltern unit isn’t hard at all. You just put the tripcock on the brake continuity circuit so that if it activates you lose brake continuity which immediately triggers an emergency brake application which can only be released once the tripcock is reset and brake continuity restored and the (usually 2 minute) timer has run down. Then the train can proceed normally. It’s the speed control thing that would be trickier.

I guess that, as national rail units operated by an national rail TOC, the normal national rail way of dealing with emergency brake applications is considered acceptable provided that they are equipped with the relevant trainstop equipment. In this particular incident, clearly the driver didn’t do the right thing by failing to apply any of the normal procedures that one would have expected. Emergency brake applications need to be investigated and reported before moving the train just to make sure you haven’t dropped one without realising.

TPWS doesn’t give any audible alert in the cab but it does give a visual one. Does the driver on a Chiltern unit get any alert that a tripcock has activated besides the brake application?

 

[bramling]

OK, so maybe now I’m not sure precisely what this system is or what it does. Is it essentially a speed limiter that runs on a timer after a tripcock activation and reset?

Stopping a Chiltern unit isn’t hard at all. You just put the tripcock on the brake continuity circuit so that if it activates you lose brake continuity which immediately triggers an emergency brake application which can only be released once the tripcock is reset and brake continuity restored and the (usually 2 minute) timer has run down. Then the train can proceed normally. It’s the speed control thing that would be trickier.

I guess that, as national rail units operated by an national rail TOC, the normal national rail way of dealing with emergency brake applications is considered acceptable provided that they are equipped with the relevant trainstop equipment. In this particular incident, clearly the driver didn’t do the right thing by failing to apply any of the normal procedures that one would have expected. Emergency brake applications need to be investigated and reported before moving the train just to make sure you haven’t dropped one without realising.

TPWS doesn’t give any audible alert in the cab but it does give a visual one. Does the driver on a Chiltern unit get any alert that a tripcock has activated besides the brake application?

With regard to SCAT on LU trains, it varies according to stock, however on the more recent trains essentially when the tripcock is reset it starts a timer, and the train can then only be operated in the driving mode where speed is limited, same as if other safety equipment is cut out (or on the ATP lines if the train is being driven without signalling protection).

Typically the driver will get an alert at about 8 mph, and a brake application over about 10 mph. I think I’m right in saying that on most or all stocks the brake application will release itself once speed is sufficiently reduced. I’m open to correction on this, but I think on some of the older stocks where this has been bolted on as an afterthought it triggers a full service not an emergency brake application, but I might be misremembering this.

SCAT is a direct consequence of a number of incidents which have occurred with drivers driving too fast when under the “stop & proceed” rule. There have been quite a few incidents over the years, four of them between Stratford and Leyton. A particularly serious one in the 1950s resulted in additional signals being provided on curved sections of single-track Tube tunnels solely for the purpose of providing additional stops when applying the rule. The fourth accident in the 1980s, again fatal, resulted in the SCAT system being developed. There was also a fatal accident on the Met Line at Kilburn around that time, this time the driver going too fast after a SPAD. There’s still a bent Fog Repeater surround at Kilburn as a relic of that incident.

This is all a bit of a blast from the past now much of LU is ATP!

 

[O L Leigh]

Ah OK. Thank you for the explanation. I was starting to wonder if we might be talking at cross purposes a bit.

So basically, LU stock can be driven away as soon as the tripcock has been reset but under the restrictions imposed by SCAT (or it’s ATP equivalent) until it times out. This explains the difference in the instructions between NR and LU drivers and why the LU driver resets the tripcock as the last action while the NR driver would want to (and probably be expected to) reset it first.

 

[bramling]

Ah OK. Thank you for the explanation. I was starting to wonder if we might be talking at cross purposes a bit.

So basically, LU stock can be driven away as soon as the tripcock has been reset but under the restrictions imposed by SCAT (or it’s ATP equivalent) until it times out. This explains the difference in the instructions between NR and LU drivers and why the LU driver resets the tripcock as the last action while the NR driver would want to (and probably be expected to) reset it first.

Exactly right. By resetting the tripcock last it keeps the timer running as long as possible, otherwise if the tripcock was reset straight away then by the time things are ready to move the timer will have long expired. It goes without saying this doesn’t absolve the driver of their liability to control the speed, as even the full 3 minutes isn’t always enough on a long section.

As I say, this *isn’t* explicitly laid down in LU’s rule book, though the way the relevant rule is written does allude to it.

I do get the distinct impression that Chiltern’s working over LU seems rather based simply upon the fact that their working over LU dates back many years. There certainly seems scope for both parties to have a bit of a shake-up to make sure the left hand knows what the right one is doing.

 

[O L Leigh]

As I say, this *isn’t* explicitly laid down in LU’s rule book, though the way the relevant rule is written does allude to it.

Maybe this is the key to the problem. If it’s expected it should be explicitly stated, and then Chiltern drivers would be aware of the requirement.

 

[bramling]

Maybe this is the key to the problem. If it’s expected it should be explicitly stated, and then Chiltern drivers would be aware of the requirement.

Agreed. LU’s rule book is nowadays rather vague, which is surprising as in the 1990s it was completely the opposite - highly prescriptive.

There is - surprisingly - no specific procedure for “Unexpected tripcock activation”. Chiltern might have their own TOC-specific instruction, or then again perhaps they didn’t and that might have been a factor, but if the rule book was fully prescriptive then there wouldn’t have been room for interpretation. In any case being LU infrastructure then the driver should be working to LU’s rule book.

This doesn’t excuse Chiltern’s management shambles though, and one way or another the driver should have known what to do to handle the situation safely.

 

[O L Leigh]

I suppose LU are more reliant on technical solutions rather than procedural ones, such as SCAT, which automatically apply the requirements of the rules. But it does leave holes, such as what happens to trains that don’t carry the relevant equipment. Under such circumstances the rules ought to be clear and not merely alluded to or left for interpretation.

I would expect that the Chiltern solution would be broadly that which we apply elsewhere on the NR network. If you get an unsolicited brake application you stop, investigate, report and then only move off once everything is clarified. We would always check TPWS to make sure that it hasn’t been activated, and I presume Chiltern drivers would also check the tripcocks (hence the question about what indications the driver receives). A lot comes down to situational awareness too. We certainly shouldn’t just reset and go as this driver did.

 

[bramling]

I suppose LU are more reliant on technical solutions rather than procedural ones, such as SCAT, which automatically apply the requirements of the rules. But it does leave holes, such as what happens to trains that don’t carry the relevant equipment. Under such circumstances the rules ought to be clear and not merely alluded to or left for interpretation.

I would expect that the Chiltern solution would be broadly that which we apply elsewhere on the NR network. If you get an unsolicited brake application you stop, investigate, report and then only move off once everything is clarified. We would always check TPWS to make sure that it hasn’t been activated, and I presume Chiltern drivers would also check the tripcocks (hence the question about what indications the driver receives). A lot comes down to situational awareness too. We certainly shouldn’t just reset and go as this driver did.

Yes I think this is spot on. From the RAIB report this driver had a history of doing it on NR as well, so there was certainly an element of ticking timebomb about it. I’d be interested to know exactly what training and instruction he would have received though, and the RAIB are surprisingly scant on that side of things.

You’re right that LU has tended to go for technical solutions - the intense nature of their infrastructure, and the fact that up until the last couple of decades LU drivers were *expected* to push the boundaries a little with their driving in order to run an intense service using traditional signals, means their systems had to be designed to be that little bit more foolproof than mainline.

To be fair, LU in the past did a superb job of reconciling and balancing intense service, safety and primitive technology. Chalfont is a bit of a backwater though, and the collective eye seems to have been taken very slightly off the ball here.

I think all parties concerned walked away lucky at Chalfont, there’s definitely shades of Ladbroke Grove about it.

 

[Falcon1200]

Was something that mitigated the consequences of this incident the fact that the Chiltern train was booked to stop at Chalfont so was approaching the station slowly ? Otherwise, as bramling says, this could have been very nasty indeed.

 

[Dstock7080]

Was something that mitigated the consequences of this incident the fact that the Chiltern train was booked to stop at Chalfont so was approaching the station slowly ? Otherwise, as bramling says, this could have been very nasty indeed.

The train passed JT6 signal at 60mph and was tripped.
It was initially accelerating when it went towards the MET train in the northbound platform.

 

[ainsworth74]

I do get the distinct impression that Chiltern’s working over LU seems rather based simply upon the fact that their working over LU dates back many years. There certainly seems scope for both parties to have a bit of a shake-up to make sure the left hand knows what the right one is doing.

Perhaps evidenced by the driver manager who was looking at this driver at the time of the incident not actually having been signed off themselves as competent on the relevant parts of the LUL rulebook despite being responsible for managing the drivers who drive over LUL infrastructure day in day out! That was a slightly draw dropping moment (amongst many) for me when I read the report.

 

[Dave W]

Perhaps evidenced by the driver manager who was looking at this driver at the time of the incident not actually having been signed off themselves as competent on the relevant parts of the LUL rulebook despite being responsible for managing the drivers who drive over LUL infrastructure day in day out! That was a slightly draw dropping moment (amongst many) for me when I read the report.

Quite, and I think this is what offers the driver some - not a lot, but some - mitigation. In any job, your employer should give you a consistent and well-led environment in which to discharge your duties. The report paints a very plain picture that this wasn't happening at Chiltern, for several reasons.

Chalfont is a bit of a backwater though, and the collective eye seems to have been taken very slightly off the ball here.

This is a very pertinent point. Often in RAIB reports you see several stars align together to turn very minor oversights and shortcomings into potentially fatal accidents. LU not knowing Chiltern's implementation of the SCAT system was insufficient, for example. Clearly there's one rather large star burning here around the driver's competency to drive trains - but the systems and procedures around him contributed.

None of this ultimately excuses the actions taken, of course.

 

[bramling]

Quite, and I think this is what offers the driver some - not a lot, but some - mitigation. In any job, your employer should give you a consistent and well-led environment in which to discharge your duties. The report paints a very plain picture that this wasn't happening at Chiltern, for several reasons.



This is a very pertinent point. Often in RAIB reports you see several stars align together to turn very minor oversights and shortcomings into potentially fatal accidents. LU not knowing Chiltern's implementation of the SCAT system was insufficient, for example. Clearly there's one rather large star burning here around the driver's competency to drive trains - but the systems and procedures around him contributed.

None of this ultimately excuses the actions taken, of course.

This could certainly quite easily have happened somewhere like Harrow, with a more serious outcome

With regards to the first point about mitigations for the driver, if I was a union rep I reckon I could make a pretty good defence case. Having said that, there do certainly seem to be suitability-for-role issues. Notwithstanding all the mess surrounding it, he still shouldn’t have done what he did.

 

[ainsworth74]

With regards to the first point about mitigations for the driver, if I was a union rep I reckon I could make a pretty good defence case. Having said that, there do certainly seem to be suitability-for-role issues. Notwithstanding all the mess surrounding it, he still shouldn’t have done what he did.

If it was his first incident I'd agree that'd give you plenty of ammunition in any disciplinary case. But with the historic background I think he'd be scuppered.

 

[bramling]

If it was his first incident I'd agree that'd give you plenty of ammunition in any disciplinary case. But with the historic background I think he'd be scuppered.

Completely agree, but I still reckon one would be able to do something with it!

 

[goldenarrow]

Anyone with experience of that part of the railway able to comment on whether there's been any reliability issues with that on the Met section?

Yes. There are long standing GSM-R issues on the MET Main, including a restriction that does not allow two Chiltern trains in the same direction to be in section in some areas.

 

[philthetube]

I suppose LU are more reliant on technical solutions rather than procedural ones, such as SCAT, which automatically apply the requirements of the rules. But it does leave holes, such as what happens to trains that don’t carry the relevant equipment. Under such circumstances the rules ought to be clear and not merely alluded to or left for interpretation.

I would expect that the Chiltern solution would be broadly that which we apply elsewhere on the NR network. If you get an unsolicited brake application you stop, investigate, report and then only move off once everything is clarified. We would always check TPWS to make sure that it hasn’t been activated, and I presume Chiltern drivers would also check the tripcocks (hence the question about what indications the driver receives). A lot comes down to situational awareness too. We certainly shouldn’t just reset and go as this driver did.

The rules are clear in that case, this is why thee ae a few class 66's with tripcocks fitted, on equipment means no running on underground metals.

If a defect develops in running then a second member of staff must ride in the cap to replace it.