Derailment at Kirkby (Merseyside) - 13/03/2021

[S&CLER]

What I always thought strange at Ormskirk was the way that the former electrified bay platform was not retained for the EMUs with the diesels using the main platform face to effect cross platform interchange. Then the bridge could still have been dispensed with. But if I recall correctly the bay platform had been lifted sometime before the through line was severed. Today the track bed there forms part of a path through to the bus station and town centre.

Obviously given the space at Ormskirk there were obviously possibilities for a different approach but Kirkby would be limited as it is in the confines of a cutting.

The bay platform wasn't long enough for 6 cars; in LMS and BR days it was worked by 5-car trains, 3 +2, and this is why some 2-car sets were included in the LMS build. The bay could not have been extended because of the bridge at the southern end, which also created a short section of substandard width platform.

 

[John Luxton]

The bay platform wasn't long enough for 6 cars; in LMS and BR days it was worked by 5-car trains, 3 +2, and this is why some 2-car sets were included in the LMS build. The bay could not have been extended because of the bridge at the southern end, which also created a short section of substandard width platform.

Thanks, I see.

I suppose if more funds had been available the bridge and consequently the platform could have been modified?

John

 

[Tomnick]

Yes indeed, step 2 or nominal 6 percent g is deemed as defensive driving. The report states normal braking point as the bridge 900 m from Kirkby. This distance less freewheel will require about 4.5 percent g, nominal step 1. The difference between step 1 and step 2 braking is around 16 seconds to full stop uniform deceleration.

Merseyrail's driving policy won't state specific "normal braking points" though, it'll be much broader than that - if, as you say, step two is considered as defensive driving, which seems reasonable for an intensive urban system, then why would the policy specify step one?

This in turn seems to imply, as others have said further up the thread, that TOC policy is step 1 braking from the M57 bridge to Kirkby station. To me, this provides a little bit of background to the speed for the first TPWS loop being set so high, given the TOC's policy for light braking may lead to variations in the braking curves between TOC policy and drivers who might employ a slightly more aggressive approach.

I think I broadly agree with your comments, apart from this bit. There's a big distinction between a company's driving policy, which is general in nature, and the driving styles and braking points taught by instructors at specific locations during practical training. It could well be that a much more gentle approach than the policy dictates is generally taught on the approach to Kirkby because, perhaps, it's known that a train running to time will have a minute or two in hand.

 

[GC class B1]

Merseyrail's driving policy won't state specific "normal braking points" though, it'll be much broader than that - if, as you say, step two is considered as defensive driving, which seems reasonable for an intensive urban system, then why would the policy specify step one?

I think I broadly agree with your comments, apart from this bit. There's a big distinction between a company's driving policy, which is general in nature, and the driving styles and braking points taught by instructors at specific locations during practical training. It could well be that a much more gentle approach than the policy dictates is generally taught on the approach to Kirkby because, perhaps, it's known that a train running to time will have a minute or two in hand.

This seems to support my view (along with the estimated stopping distances in my post no 588), that the set speed for the PSR OSS loops could be set lower and possibly moved to a greater distance from the PSR, without causing problems as a result of unnecessary operation under normal braking.

 

[tomuk]

This seems to support my view (along with the estimated stopping distances in my post no 588), that the set speed for the PSR OSS loops could be set lower without causing problems as a result of unnecessary operation under normal braking.

I'm not saying there were but I could see drivers taking it easy on approach to Kirkby if there had been spurious activations in the past and some leeway during the turnaround. NR fix the problem but the precaution lingers on.

 

[niggill617@gma]

I'm not saying there were but I could see drivers taking it easy on approach to Kirkby if there had been spurious activations in the past and some leeway during the turnaround. NR fix the problem but the precaution lingers on.

I suspect many drivers would not accelerate to 60 mph: to save about 10 seconds over 1900 m, just to use more fuel, and produce extra brake dust. Is the TPWS set for 60 mph or 50 mph ? The report lacks investigation regarding TPWS logic?

 

[zwk500]

I suspect many drivers would not accelerate to 60 mph: to save about 10 seconds over 1900 m, just to use more fuel, and produce extra brake dust.

Merseyrail units are electric (so wouldn't use fuel) and have disc & rheostatic brakes, I believe (so don't produce as much brake dust). I agree accelerating to the full 60 is unlikely, for a smoother journey.

Is the TPWS set for 60 mph or 50 mph ?

Different TPWS grids are set to different trigger speeds.

The report lacks investigation regarding TPWS logic?

What would you expect the report to have investigated regarding TPWS in this incident?

 

[43066]

I suspect many drivers would not accelerate to 60 mph: to save about 10 seconds over 1900 m, just to use more fuel, and produce extra brake dust. Is the TPWS set for 60 mph or 50 mph ? The report lacks investigation regarding TPWS logic?

With a short gap between stations I’d generally accelerate harder and brake harder! That’s the way it generally works with metro ops.

As others have said, that’s completely different when you’re talking about approaching a terminal location with trigger happy TPWS.

 

[GC class B1]

Merseyrail units are electric (so wouldn't use fuel) and have disc & rheostatic brakes, I believe (so don't produce as much brake dust). I agree accelerating to the full 60 is unlikely, for a smoother journey.

Electric multiple units use fuel, the fuel is electricity.

What would you expect the report to have investigated regarding TPWS in this incident?

A previous RAIB report into an incident involving a serious SPAD with a potential conflict (Report No, 23/2008) found that because the TPWS installation was designed for Traction with an Emergency braking performance and the train involved had an Emergency brake deceleration rate less than 12%g, then the TPWS installation was causal to the incident.

 

[mcmad]

A previous RAIB report into an incident involving a serious SPAD with a potential conflict (Report No, 23/2008) found that because the TPWS installation was designed for Traction with an Emergency braking performance and the train involved had an Emergency brake deceleration rate less than 12%g, then the TPWS installation was causal to the incident.

So surely the fact no comment is made around the TPWS installations (other than it complies with standards) means RAIB had no issues with it despite all this armchair wibble.

 

[niggill617@gma]

So surely the fact no comment is made around the TPWS installations (other than it complies with standards) means RAIB had no issues with it despite all this armchair wibble.

The OSS distance is calculated with regard to 10 mph above line speed, so it should be set to 70 mph or 415 m. I guess that 70 mph is not attainable at this location, which is why the set distance is calculated as 60 mph or 295 m ?

 

[zwk500]

A previous RAIB report into an incident involving a serious SPAD with a potential conflict (Report No, 23/2008) found that because the TPWS installation was designed for Traction with an Emergency braking performance and the train involved had an Emergency brake deceleration rate less than 12%g, then the TPWS installation was causal to the incident.

That was a different incident with a different conflict being protected.
Specifically in this incident, what aspect of the TPWS system should have been investigated as part of the RAIBs work to determine what caused this accident and whether anything can be learned from it?

 

[GC class B1]

That was a different incident with a different conflict being protected.
Specifically in this incident, what aspect of the TPWS system should have been investigated as part of the RAIBs work to determine what caused this accident and whether anything can be learned from it?

From studying earlier posts in this thread a number of points have been raised regarding the potential for the first set of TPWS OSS loops to mitigate the results of the driver overspeeding at the commencement of the 15MPH speed limit and the seconds set of OSS loops for the buffer stop not being able to prevent the collision with the buffer stops at speed. One point suggested above is that the 60 MPH line speed limit dictated the set speed for the OSS loops protecting the 15 MPH PSR. Both Merseyrail driving policy and the likelihood that the 60 MPH speed would not be achieved would have permitted the set speed to be reduced and thereby increased the likelihood that the OSS loops would have initiated an Emergency brake application and mitigated the effect of the overspeeding without compromising the operation of the service. It is possible that this modification to the design of the TPWS would have prevented the buffer stop collision. There may be other aspects of the TPWS installation that could be considered to prevent future incidents at similar locations including additional OSS loops.

 

[zwk500]

From studying earlier posts in this thread a number of points have been raised regarding the potential for the first set of TPWS OSS loops to mitigate the results of the driver overspeeding at the commencement of the 15MPH speed limit and the seconds set of OSS loops for the buffer stop not being able to prevent the collision with the buffer stops at speed. One point suggested above is that the 60 MPH line speed limit dictated the set speed for the OSS loops protecting the 15 MPH PSR. Both Merseyrail driving policy and the likelihood that the 60 MPH speed would not be achieved would have permitted the set speed to be reduced and thereby increased the likelihood that the OSS loops would have initiated an Emergency brake application and mitigated the effect of the overspeeding without compromising the operation of the service. It is possible that this modification to the design of the TPWS would have prevented the buffer stop collision. There may be other aspects of the TPWS installation that could be considered to prevent future incidents at similar locations including additional OSS loops.

The first OSS is set to 53mph, and the 15mph TSS was not part of the incident as the emergency brake had already been activated. What modifications to this setup do you think would help safety without placing an undue burden on operating the service or putting the drivers under more pressure?

 

[GC class B1]

The first OSS is set to 53mph, and the 15mph TSS was not part of the incident as the emergency brake had already been activated. What modifications to this setup do you think would help safety without placing an undue burden on operating the service or putting the drivers under more pressure?

My understanding is that normal driving practice is to approach the terminal station at Kirkby at a much slower speed than the 60 MPH line speed would permit. It seems that with a set speed of 53 mph the OSS loops for the PSR will never be triggered. I have calculated that the normal driving technique will mean that trains will pass over these loops at less than 40 MPH when braking for the PSR. A set speed of just above this speed would mean that for a train coasting or running at about 50 mph an Emergency brake application would be initiated and the train speed would be reduced such that if not already braking at the TSS protecting the buffer stop an Emergency brake application would prevent a buffer stop collision if these loops were set correctly. This are my thoughts and would need to be verified by someone with the skills necessary.
The current driving technique would not need to be changed and would not put drivers under increased pressure but they would be reassured that TPWS would intervene in the unlikely event that they became disoriented.

 

[507020]

We do of course have to remember that both TPWS loops will likely be removed altogether when Kirkby reverts to a through station later this year, in favour of the purpose built terminus at Headbolt Lane which I am sure will have been designed with this incident in mind as well as including modern safety measures like friction buffers on all platforms.

 

[zwk500]

We do of course have to remember that both TPWS loops will likely be removed altogether when Kirkby reverts to a through station later this year, in favour of the purpose built terminus at Headbolt Lane which I am sure will have been designed with this incident in mind as well as including modern safety measures like friction buffers on all platforms.

True, although a similar TPWS setup likely exists at Ormskirk.

 

[philthetube]

The first OSS is set to 53mph, and the 15mph TSS was not part of the incident as the emergency brake had already been activated. What modifications to this setup do you think would help safety without placing an undue burden on operating the service or putting the drivers under more pressure?

I would think that an additional loop set to 25 mph outside the station, set at a braking distance for normal stopping would be a big help, it may not prevent accidents like this one but it would have reduced the consequences.

 

[plugwash]

The other obvious change IMO would be to enlarge the platforms and slew the track so that if a train did puch through the buffer stops it didn't hit the walkway.

 

[niggill617@gma]

That was a different incident with a different conflict being protected.
Specifically in this incident, what aspect of the TPWS system should have been investigated as part of the RAIBs work to determine what caused this accident and whether anything can be learned from it?

Different incident / conflict ? not really; TPWS = initial speed and target speed, possibly zero. Distance and set speed of OSS grids based on two different rates of deceleration.

 

[craigybagel]

At the end of the day, it wasn't a failing of TPWS that caused this incident, but a failing of professionalism. As long as you're relying on TPWS rather than a full ATP system you're going to have cracks that trains can fall through. You could have 10 different TPWS loops on the approach to the platform at Kirkby - but you still wouldn't be able to entirely remove the risk of a train hitting the barriers. You'd also probably destroy the timetable through requiring trains to arrive so slowly as to avoid tripping the grids.

I suspect you'd find a more effective way to improve safety overall would be to step up surveillance of phone use in cabs. It would seem an astonishing piece of bad luck if this was the first time the driver used their phone in the cab - but if they'd been caught previously, we wouldn't be having this discussion on TPWS.

All drivers know that phones are meant to be switched off - and that the use of one in a live cab is a potentially sackable offence (even aside from the risk of an incident like this). The fact that this driver was seemingly pretty relaxed about using theirs - and if the rumours are true, using it to discuss an extremely trivial issue that had nothing to do with their life - is I feel a lot more worrying than any failings of TPWS.

 

[tomuk]

The driver concerned was sacked and was sentenced to 12 months in prison, suspended for 2 years after a trail. I think that deals with the lack of professionalism.

The report notes that the driver rather than a clean record had had a number of issues and had been through an improvement plan.

The RAIB have recommend

Merseyrail, working with Network Rail, should review the process of risk assessing buffer stop collisions to ensure that it identifies all foreseeable situations which could lead to a collision, and applies appropriate risk control measures.

What would these control measures be?

 

[507020]

True, although a similar TPWS setup likely exists at Ormskirk.

I don’t think there is. At Ormskirk the track doubles immediately outside the platform and arriving trains often have to wait at a signal for the departing train before entering the platform. Likewise at Southport the station is protected by a sharp bend that requires trains to slow down before entering the station. The long fast single track run was unique to Kirkby.

At the end of the day, it wasn't a failing of TPWS that caused this incident, but a failing of professionalism. As long as you're relying on TPWS rather than a full ATP system you're going to have cracks that trains can fall through. You could have 10 different TPWS loops on the approach to the platform at Kirkby - but you still wouldn't be able to entirely remove the risk of a train hitting the barriers. You'd also probably destroy the timetable through requiring trains to arrive so slowly as to avoid tripping the grids.

I suspect you'd find a more effective way to improve safety overall would be to step up surveillance of phone use in cabs. It would seem an astonishing piece of bad luck if this was the first time the driver used their phone in the cab - but if they'd been caught previously, we wouldn't be having this discussion on TPWS.

All drivers know that phones are meant to be switched off - and that the use of one in a live cab is a potentially sackable offence (even aside from the risk of an incident like this). The fact that this driver was seemingly pretty relaxed about using theirs - and if the rumours are true, using it to discuss an extremely trivial issue that had nothing to do with their life - is I feel a lot more worrying than any failings of TPWS.

The argument on here has been given its limitations, TPWS installations should be designed to mitigate primarily against failures of professionalism i.e. rolling stock not being operated correctly, since when being driven correctly and professionally, there is little risk of a collision except in circumstances of extreme low adhesion in which case an emergency brake application and therefore TPWS would have little effect.

What would these control measures be?

Current industry standard practice. It was noted that the risk control measures Merseyrail had in place were outdated and therefore deemed inappropriate.

 

[craigybagel]

The driver concerned was sacked and was sentenced to 12 months in prison, suspended for 2 years after a trail. I think that deals with the lack of professionalism.

It deals with HIS lack of professionalism, after the incident occurred. It doesn't do much to stop it happening again in future.

It just feels a bit like all this talk over what TPWS should have done is missing the point somewhat.

 

[niggill617@gma]

At the end of the day, it wasn't a failing of TPWS that caused this incident, but a failing of professionalism. As long as you're relying on TPWS rather than a full ATP system you're going to have cracks that trains can fall through. You could have 10 different TPWS loops on the approach to the platform at Kirkby - but you still wouldn't be able to entirely remove the risk of a train hitting the barriers. You'd also probably destroy the timetable through requiring trains to arrive so slowly as to avoid tripping the grids.

I suspect you'd find a more effective way to improve safety overall would be to step up surveillance of phone use in cabs. It would seem an astonishing piece of bad luck if this was the first time the driver used their phone in the cab - but if they'd been caught previously, we wouldn't be having this discussion on TPWS.

All drivers know that phones are meant to be switched off - and that the use of one in a live cab is a potentially sackable offence (even aside from the risk of an incident like this). The fact that this driver was seemingly pretty relaxed about using theirs - and if the rumours are true, using it to discuss an extremely trivial issue that had nothing to do with their life - is I feel a lot more worrying than any failings of TPWS.

As the railway usually works to the lowest common denominator, perhaps private mobile phones should be banned from cabs in there entirety. Company phones can then be randomly checked. I believe this will help but not totally eliminate the temptation.

You see some drivers walking around almost permanently with a phone growing from their ear, makes you wonder?

 

[Dai Corner]

As the railway usually works to the lowest common denominator, perhaps private mobile phones should be banned from cabs in there entirety. Company phones can then be randomly checked. I believe this will help but not totally eliminate the temptation.

You see some drivers walking around almost permanently with a phone growing from their ear, makes you wonder?

They are, aren't they? Unless out of reach and sight of the driver.

 

[tomuk]

Current industry standard practice. It was noted that the risk control measures Merseyrail had in place were outdated and therefore deemed inappropriate.

I believe you are incorrectly conflating the separate recommendation regarding fatigue

 

[Stigy]

As the railway usually works to the lowest common denominator, perhaps private mobile phones should be banned from cabs in there entirety. Company phones can then be randomly checked. I believe this will help but not totally eliminate the temptation.

You see some drivers walking around almost permanently with a phone growing from their ear, makes you wonder?

Phones are banned in cabs. Not having your phone switched on is surely the same as being banned in the first place. Unless there’s a serious incident like this one, it would be almost impossible to police, too.

 

[bramling]

Phones are banned in cabs. Not having your phone switched on is surely the same as being banned in the first place. Unless there’s a serious incident like this one, it would be almost impossible to police, too.

To be brutally honest, it shouldn’t need to be policed. Part of the reason train drivers get good remuneration is because there’s an expectation that they are capable of managing these things for themselves.

If the prospect of a having an incident (and being in possibly the most vulnerable position on the train), losing job, and perhaps a prison sentence, isn’t enough then what realistically is?

 

[Stigy]

To be brutally honest, it shouldn’t need to be policed. Part of the reason train drivers get good remuneration is because there’s an expectation that they are capable of managing these things for themselves.

If the prospect of a having an incident (and being in possibly the most vulnerable position on the train), losing job, and perhaps a prison sentence, isn’t enough then what realistically is?

I agree, but then, there’s no point in updating policy in that case.