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And that would have almost certainly been the case even if he’d been able to answer friction maths problems.
Absolutely. Of course some stock has a brake % gauge driven from an accelerometer which gives you an idea of deceleration rate, but of course “seat of the pants” feel is more important.
With respect that might be your interpretation, but it means nought when the industry and its masters evidently don’t agree with you. For the record freight drivers don’t have to learn to do these calculations either.
Agree with this and it does seem that something went wrong in the case of the Caledonian sleeper, for whatever reason. I’m just not remotely convinced the OP’s suggested approach would have made the blindest bit of difference. Quite honestly if a train is relying on a running brake test to determine that most of the brakes are disconnected, it’s already too late (RBTs are to gauge railhead conditions rather than checking the brakes are working!)
The most useful learning point from that incident was the importance of ensuring adequate training on new stock.
The basic parameter of a normal passenger train, is a nominal braking performance of 0.8 metres per second squared at least ( maybe more). No calculation here just understanding. (some consists will have an enhanced rate, such as class 800 1.2 m/s2) Therefore if a 50 percent running brake test is executed the rate is 0.4 m/s2. No calculation here either other than divide by two. For a 10 mph reduction running brake test, the time taken will be around 11 seconds. Some basic understanding required here. This calculation is easily understood when explained by a professional tutor. Education is wasted on kids. Regarding the Edinburgh running brake test; the 11 mph reduction in speed took around 26 seconds. Take away 6 seconds build up time and we have 20 seconds. The poor performance is clearly evident to the informed. The drivers inbuilt accelerometer, was probably tilted because of the dynamic brake providing around 0.2m/s2 in the first few seconds.
The general procedure is as per #45 where I use 0.45 m/s2 as the example figure, there will always be some empirical error, but it is well in the ballpark. This incident is not the only one in recent times. All the previous incidents involve highly experienced drivers.
Aside, if the percent brake gauge is supplied by an accelerometer why does it register when the consist is stationary. I suspect you mean potentiometer.
The basic parameter of a normal passenger train, is a maximum braking performance of 0.8 metres per second squared at least ( maybe more). No calculation here just understanding. (some consists will have an enhanced rate, such as class 800 1.2 m/s2) Therefore if a 50 percent running brake test is executed the rate is 0.4 m/s2. No calculation here either other than divide by two. For a 10 mph reduction running brake test, the time taken will be around 11 seconds. Some basic understanding required here. This calculation is easily understood when explained by a professional tutor. Education is wasted on kids. Regarding the Edinburgh running brake test; the 11 mph reduction in speed took around 26 seconds. Take away 6 seconds build up time and we have 20 seconds. The poor performance is clearly evident to the informed. The drivers inbuilt accelerometer, was probably tilted because of the dynamic brake providing around 0.2m/s2 in the first few seconds.
The general procedure is as per #45 where I use 0.45 m/s2 as the example figure, there will always be some empirical error, but it is well in the ballpark. This incident is not the only one in recent times. All the previous incidents involve highly experienced drivers.
Aside, if the percent brake gauge is supplied by an accelerometer why does it register when the consist is stationary. I suspect you mean potentiometer.
In order to comply with the BS EN 14198, the standard applicable for the braking system design of the sleeping cars, they would need to brake at about 1 m/s/s (I.e about 10% g). This standard requires a brake percentage (lambda) for passenger vehicles of 105 to125. 10% g deceleration would give a stopping distance from 75 Mph of about 650 metres with a brake build up time 5 seconds and therefore a brake percentage of 109.
Assuming the class 92 locomotive braked at 6% g, the deceleration rate for the sleeper train should have been about 9% g. Niggil617@gma is essentially correct in his calculation, However I think his calculation of the time taken to reduce the speed by 10 Mph (about 4.5 m/s) at 50% brake (0.45m/s/s) is conservative as my calculation is as follows.
Time to establish 50 % brake would be about 4 seconds and in this time to the speed would have reduced by at least 1 Mph so the remaining 9 Mph reduction would take less than 9 seconds.
The total time to reduce the speed by 10 mph at 50% brake with a fully functioning brake system should therefore be no more than 13 seconds.
In order to comply with the BS EN 14198, the standard applicable for the braking system design of the sleeping cars, they would need to brake at about 0.1 m/s/s (I.e about 10% g). This standard requires a brake percentage (lambda) for passenger vehicles of 105 to125. 10% g deceleration would give a stopping distance from 75 Mph of about 650 metres with a brake build up time 5 seconds and therefore a brake percentage of 109.
Assuming the class 92 locomotive braked at 6% g, the deceleration rate for the sleeper train should have been about 9% g. Niggil617@gma is essentially correct in his calculation, However I think his calculation of the time taken to reduce the speed by 10 Mph (about 4.5 m/s) at 50% brake (0.45m/s/s) is conservative as my calculation is as follows.
Time to establish 50 % brake would be about 4 seconds and in this time to the speed would have reduced by at least 1 Mph so the remaining 9 Mph reduction would take less than 9 seconds.
The total time to reduce the speed by 10 mph at 50% brake with a fully functioning brake system should therefore be no more than 13 seconds.
I wondered if the mark 5 stock would be within the enhanced range. Just a typo on first line should read 1.0 m/s/s, not 0.1 above. The conclusion is simply the dynamic brake masks nothing. Something needs to fundamentally be actioned, if a running brake test fails to highlight such an error.
The driver and his shunter had good intensions no question. This incident need not of happened, had the TDLCR been firstly: interrupted properly, and secondly actioned. Not the fault of the driver. The almost instant feel of inertia from the dynamic brake, probably gave a false sense of performance.
== Doublepost prevention - post automatically merged: ==
I wondered if the mark 5 stock would be within the enhanced range. Just a typo on first line should read 1.0 m/s/s, not 0.1 above. The conclusion is simply the dynamic brake masks nothing. Something needs to fundamentally be actioned, if a running brake test fails to highlight such an error.
The driver and his shunter had good intensions no question. This incident need not of happened, had the TDLCR been firstly: interrupted properly, and secondly actioned. Not the fault of the driver. The almost instant feel of inertia from the dynamic brake, probably gave a false sense of performance.
Another point on the physics thing regarding a meaningful running brake test.
The emergency protection distance is the well known 1 and a quarter mile. This means for a high speed 125 mph train, the rate of retardation to stop within this distance, is 0.84 m/s/s, allowing for 2 seconds freewheel on the level. Therefore a running brake test on such a consist, 800 for example should be 70 percent on the percent gauge. My former TOC forbid the use of said instrument. The time to reduce speed for such a test is just under 6 seconds, for a 10 mph reduction, with established retarding force. A little stab of the brakes proves nothing, other than ticking the box. Would you want to do such a test during leaf fall?
I appreciate driveability plays here, just food for thought. Luckily Braking systems are well designed and maintained by conscientious engineers and technicians.
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The basic parameter of a normal passenger train, is a maximum braking performance of 0.8 metres per second squared at least ( maybe more). No calculation here just understanding. (some consists will have an enhanced rate, such as class 800 1.2 m/s2) Therefore if a 50 percent running brake test is executed the rate is 0.4 m/s2. No calculation here either other than divide by two. For a 10 mph reduction running brake test, the time taken will be around 11 seconds. Some basic understanding required here. This calculation is easily understood when explained by a professional tutor. Education is wasted on kids. Regarding the Edinburgh running brake test; the 11 mph reduction in speed took around 26 seconds. Take away 6 seconds build up time and we have 20 seconds. The poor performance is clearly evident to the informed. The drivers inbuilt accelerometer, was probably tilted because of the dynamic brake providing around 0.2m/s2 in the first few seconds.
The general procedure is as per #45 where I use 0.45 m/s2 as the example figure, there will always be some empirical error, but it is well in the ballpark. This incident is not the only one in recent times. All the previous incidents involve highly experienced drivers.
Aside, if the percent brake gauge is supplied by an accelerometer why does it register when the consist is stationary. I suspect you mean potentiometer.
Paragraph 28 of the Edinburgh report states; a reading of 3.5 bar BPP, equates to a full service brake application. If the extreme right side of the trace attached, illustrates zero brake brake pipe pressure, the brake test must be a full service application? If interpolation is correct so are the majority of the subsequent brake applications.
The dynamic brake emulates the friction brake so the application and performance is the same.
== Doublepost prevention - post automatically merged: ==
I wondered if the mark 5 stock would be within the enhanced range. Just a typo on first line should read 1.0 m/s/s, not 0.1 above. The conclusion is simply the dynamic brake masks nothing. Something needs to fundamentally be actioned, if a running brake test fails to highlight such an error.
The driver and his shunter had good intensions no question. This incident need not of happened, had the TDLCR been firstly: interrupted properly, and secondly actioned. Not the fault of the driver. The almost instant feel of inertia from the dynamic brake, probably gave a false sense of performance.
== Doublepost prevention - post automatically merged: ==
Another point on the physics thing regarding a meaningful running brake test.
The emergency protection distance is the well known 1 and a quarter mile. This means for a high speed 125 mph train, the rate of retardation to stop within this distance, is 0.84 m/s/s, allowing for 2 seconds freewheel on the level. Therefore a running brake test on such a consist, 800 for example should be 70 percent on the percent gauge. My former TOC forbid the use of said instrument. The time to reduce speed for such a test is just under 6 seconds, for a 10 mph reduction, with established retarding force. A little stab of the brakes proves nothing, other than ticking the box. Would you want to do such a test during leaf fall?
I appreciate driveability plays here, just food for thought. Luckily Braking systems are well designed and maintained by conscientious engineers and technicians.
== Doublepost prevention - post automatically merged: ==
Paragraph 28 of the Edinburgh report states; a reading of 3.5 bar BPP, equates to a full service brake application. If the extreme right side of the trace attached, illustrates zero brake brake pipe pressure, the brake test must be a full service application? If interpolation is correct so are the majority of the subsequent brake applications.
The dynamic brake emulates the friction brake so the application and performance is the same.
I have requested the RAIB to clarify the brake pipe pressure, of the Edinburgh Sleeper via their enquiry contact email. They will not answer, so I have complained to the ORR as to my rights of disclosure.
The brake force of the locomotive dynamic brake is 63 tonnes equivalent, I suspect the all up mass of the consist is around 480 tonnes? These figures calculate to a full service deceleration of 0.167 m/s/s. The running brake test calculates to around 0.172 m/s/s.
As a member of the public I do not have any authority over the "Rail Bodies", however I do have the right to challenge.
I await the response from the ORR.
== Doublepost prevention - post automatically merged: ==
I wondered if the mark 5 stock would be within the enhanced range. Just a typo on first line should read 1.0 m/s/s, not 0.1 above. The conclusion is simply the dynamic brake masks nothing. Something needs to fundamentally be actioned, if a running brake test fails to highlight such an error.
The driver and his shunter had good intensions no question. This incident need not of happened, had the TDLCR been firstly: interrupted properly, and secondly actioned. Not the fault of the driver. The almost instant feel of inertia from the dynamic brake, probably gave a false sense of performance.
== Doublepost prevention - post automatically merged: ==
Another point on the physics thing regarding a meaningful running brake test.
The emergency protection distance is the well known 1 and a quarter mile. This means for a high speed 125 mph train, the rate of retardation to stop within this distance, is 0.84 m/s/s, allowing for 2 seconds freewheel on the level. Therefore a running brake test on such a consist, 800 for example should be 70 percent on the percent gauge. My former TOC forbid the use of said instrument. The time to reduce speed for such a test is just under 6 seconds, for a 10 mph reduction, with established retarding force. A little stab of the brakes proves nothing, other than ticking the box. Would you want to do such a test during leaf fall?
I appreciate driveability plays here, just food for thought. Luckily Braking systems are well designed and maintained by conscientious engineers and technicians.
== Doublepost prevention - post automatically merged: ==
Paragraph 28 of the Edinburgh report states; a reading of 3.5 bar BPP, equates to a full service brake application. If the extreme right side of the trace attached, illustrates zero brake brake pipe pressure, the brake test must be a full service application? If interpolation is correct so are the majority of the subsequent brake applications.
The dynamic brake emulates the friction brake so the application and performance is the same.
== Doublepost prevention - post automatically merged: ==
I have requested the RAIB to clarify the brake pipe pressure, of the Edinburgh Sleeper via their enquiry contact email. They will not answer, so I have complained to the ORR as to my rights of disclosure.
The brake force of the locomotive dynamic brake is 63 tonnes equivalent, I suspect the all up mass of the consist is around 480 tonnes? These figures calculate to a full service deceleration of 0.167 m/s/s. The running brake test calculates to around 0.172 m/s/s.
As a member of the public I do not have any authority over the "Rail Bodies", however I do have the right to challenge.
Consult fig 3 of the Edinburgh report. The braking profile suggests the driver had no confidence in the braking performance?
1. The service is running 19 mins late, yet line speed is not utilised.
2. Braking commences over 5 miles from the 70 mph speed restriction; for a 17 mph reduction in speed.
3. A train with 8 percent g braking, would only require 4 percent g, taking 1100 m , to slow from 87 to 70 mph. This would include freewheel and gradient component.
== Doublepost prevention - post automatically merged: ==
Looks like Schedule 3 exam is now active, with the Academy.
I wondered if the mark 5 stock would be within the enhanced range. Just a typo on first line should read 1.0 m/s/s, not 0.1 above. The conclusion is simply the dynamic brake masks nothing. Something needs to fundamentally be actioned, if a running brake test fails to highlight such an error.
The driver and his shunter had good intensions no question. This incident need not of happened, had the TDLCR been firstly: interrupted properly, and secondly actioned. Not the fault of the driver. The almost instant feel of inertia from the dynamic brake, probably gave a false sense of performance.
== Doublepost prevention - post automatically merged: ==
Another point on the physics thing regarding a meaningful running brake test.
The emergency protection distance is the well known 1 and a quarter mile. This means for a high speed 125 mph train, the rate of retardation to stop within this distance, is 0.84 m/s/s, allowing for 2 seconds freewheel on the level. Therefore a running brake test on such a consist, 800 for example should be 70 percent on the percent gauge. My former TOC forbid the use of said instrument. The time to reduce speed for such a test is just under 6 seconds, for a 10 mph reduction, with established retarding force. A little stab of the brakes proves nothing, other than ticking the box. Would you want to do such a test during leaf fall?
I appreciate driveability plays here, just food for thought. Luckily Braking systems are well designed and maintained by conscientious engineers and technicians.
== Doublepost prevention - post automatically merged: ==
Paragraph 28 of the Edinburgh report states; a reading of 3.5 bar BPP, equates to a full service brake application. If the extreme right side of the trace attached, illustrates zero brake brake pipe pressure, the brake test must be a full service application? If interpolation is correct so are the majority of the subsequent brake applications.
The dynamic brake emulates the friction brake so the application and performance is the same.
== Doublepost prevention - post automatically merged: ==
I have requested the RAIB to clarify the brake pipe pressure, of the Edinburgh Sleeper via their enquiry contact email. They will not answer, so I have complained to the ORR as to my rights of disclosure.
The brake force of the locomotive dynamic brake is 63 tonnes equivalent, I suspect the all up mass of the consist is around 480 tonnes? These figures calculate to a full service deceleration of 0.167 m/s/s. The running brake test calculates to around 0.172 m/s/s.
As a member of the public I do not have any authority over the "Rail Bodies", however I do have the right to challenge.
I await the response from the ORR.
== Doublepost prevention - post automatically merged: ==
Consult fig 3 of the Edinburgh report. The braking profile suggests the driver had no confidence in the braking performance?
1. The service is running 19 mins late, yet line speed is not utilised.
2. Braking commences over 5 miles from the 70 mph speed restriction; for a 17 mph reduction in speed.
3. A train with 8 percent g braking, would only require 4 percent g, taking 1100 m , to slow from 87 to 70 mph. This would include freewheel and gradient component.
== Doublepost prevention - post automatically merged: ==
Looks like Schedule 3 exam is now active, with the Academy.
6 percent g is the name of the game. Having said that; when double variable rate sanders are the norm, the extra braking power can be a preference for normal ops.
As static friction between rail and wheel lowers at higher speed, the sanders should of course be tested at that speed, not 55 mph as is the current situation I believe?
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Schedule 5 clearly states calculate, as does schedule 3.
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6 percent g is the name of the game. Having said that; when double variable rate sanders are the norm, the extra braking power can be a preference for normal ops.
As static friction between rail and wheel lowers at higher speed, the sanders should of course be tested at that speed, not 55 mph as is the current situation I believe?
The defensive driving braking point of 2568 m or 1.6 of a mile from 125 mph, will require 514 m sighting or 9.2 seconds, if the minimum signalled braking distance is the case. Most of the locations will be more, subject to 50 percent excess maximum, notwithstanding derogation.
Summary states; 20 mph past signal for 200m, This equates to a max deceleration of 0.2 m/s/s. About half of what it should be. Therefore is the rear loco providing any braking force?
Fact- Paragraph 44 states 75 mph plus; 3200 m from red.
Fact - RAIB state 15 seconds freewheel- I have the email. ( must be set to freight timings?)
Bearing in mind TDLCR states drivers must be able to calculate braking performance.
20 mph entry speed followed by 200 m displacement equals a deceleration of 0.199 m/s/s. That rate of deceleration is approximately 50 percent of what it should be, suggesting the rear loco is failing to contribute any braking power.
Paragraph 28 of the report states the consist is 75 mph plus (76 mph) 3200 m from red. Full service or emergency at this point would yield; 15 seconds freewheel = 510 m. V squared divided by 0.398 = 2900 m. Total distance = 3410 m or 210 m Spad.
The driver states poor braking performance (para 29) approaching the signal, so why wait 820 m past the yellow before selecting full service / emergency?
RAIB reports are for the consumption of the public, and therefore open to criticism albeit calculation. I have asked RAIB to explain, which is my right via the public enquiry email service.
The driver states poor braking performance (para 29) approaching the signal, so why wait 820 m past the yellow before selecting full service / emergency?
Although the driver was aware of poor braking performance, perhaps (wrongly) he thought he/she had it under control.
Or are you going to come out with your usual claptrap that if he/she had a physics qualification and could calculate deceleration and Braking Performance then it wouldn’t have happened?
Summary states; 20 mph past signal for 200m, This equates to a max deceleration of 0.2 m/s/s. About half of what it should be. Therefore is the rear loco providing any braking force?
Fact- Paragraph 44 states 75 mph plus; 3200 m from red.
Fact - RAIB state 15 seconds freewheel- I have the email. ( must be set to freight timings?)
Bearing in mind TDLCR states drivers must be able to calculate braking performance.
@niggill617@gma , you may be detecting some scepticism in the replies you are getting. And I note that many of the railway professionals who are on this forum are not engaging with this discussion.
I'm not in the profession, but I am a professional mathematician, and am qualified to read and understand the legislation you are referring to.
I think you are referring to Schedule 4 of the Train Driving Licenses and Certificate Regulations of 2010, which state that "Drivers must be able to check and calculate, before departure, that the train's braking power corresponds to the braking power required for the line, as specified in the vehicle documents." I think the key phrase here is 'before departure'. It means that this is not a calculation based on empirical evidence, but based on the information provided. On that basis, this must therefore be referring to a very simple arithmetical calculation, not the kind of physics based calculations you are talking about.
While I understand why it might be attractive to think that drivers should be able to hold mathematical models in their head that are able to account for a large number of variables, it's actually not a good idea. Such a calculation is cognitively difficult - even for experienced mathematicians. And any potential benefit will be more than outweighed by the risk of distraction.
The law reflects this - there is no requirement for calculations to be made 'on the fly'. And I cannot see any possibility that a responsible group of lawmakers would think that this would be a good idea.
It would seem to me that the regulations strike a good balance - yes drivers should take time to consider whether the known capabilities of the train are suitable for the route to be taken before starting off. And with a suitable amount of experience of driving, they should be able to detect if something is not working as expected, without having to justify it with a needlessly complicated calculation.
I don't see any possibility of the change you are advocating ever happening.
@niggill617@gma , you may be detecting some scepticism in the replies you are getting. And I note that many of the railway professionals who are on this forum are not engaging with this discussion.
I'm not in the profession, but I am a professional mathematician, and am qualified to read and understand the legislation you are referring to.
I think you are referring to Schedule 4 of the Train Driving Licenses and Certificate Regulations of 2010, which state that "Drivers must be able to check and calculate, before departure, that the train's braking power corresponds to the braking power required for the line, as specified in the vehicle documents." I think the key phrase here is 'before departure'. It means that this is not a calculation based on empirical evidence, but based on the information provided. On that basis, this must therefore be referring to a very simple arithmetical calculation, not the kind of physics based calculations you are talking about.
While I understand why it might be attractive to think that drivers should be able to hold mathematical models in their head that are able to account for a large number of variables, it's actually not a good idea. Such a calculation is cognitively difficult - even for experienced mathematicians. And any potential benefit will be more than outweighed by the risk of distraction.
The law reflects this - there is no requirement for calculations to be made 'on the fly'. And I cannot see any possibility that a responsible group of lawmakers would think that this would be a good idea.
It would seem to me that the regulations strike a good balance - yes drivers should take time to consider whether the known capabilities of the train are suitable for the route to be taken before starting off. And with a suitable amount of experience of driving, they should be able to detect if something is not working as expected, without having to justify it with a needlessly complicated calculation.
I don't see any possibility of the change you are advocating ever happening.
A static brake test before departure, exactly what every driver does (should!) before taking a unit out.
Hoorah hoorah for some common sense at last.
Thank you @ WideRanger.
A static brake test before departure, exactly what every driver does (should!) before taking a unit out.
Hoorah hoorah for some common sense at last.
Thank you @ WideRanger.
I will reply to all posts, in order, in due course.
#66 - Train Driver and Licensing Certificate Regulations. Yes I wanted to kick start this thread.
#68 - I have asked RAIB many questions over the last 18 months or so. I usually get politician type replies. Regarding Loughborough I find this report economical with facts, notwithstanding no data from the OTMR. I had to ask RAIB the distance from yellow to red. This is a fundamental fact, unlike para 51. I have further asked what is the source of the data: 20 mph past the signal for 200 m, is it absolute, how approximate is approximately. The train would have passed the signal at 30 mph for this to fit with fig 7. The graph reflects 15 seconds freewheel, had to extract this from RAIB as well inter alia.
@niggill617@gma , you may be detecting some scepticism in the replies you are getting. And I note that many of the railway professionals who are on this forum are not engaging with this discussion.
I'm not in the profession, but I am a professional mathematician, and am qualified to read and understand the legislation you are referring to.
I think you are referring to Schedule 4 of the Train Driving Licenses and Certificate Regulations of 2010, which state that "Drivers must be able to check and calculate, before departure, that the train's braking power corresponds to the braking power required for the line, as specified in the vehicle documents." I think the key phrase here is 'before departure'. It means that this is not a calculation based on empirical evidence, but based on the information provided. On that basis, this must therefore be referring to a very simple arithmetical calculation, not the kind of physics based calculations you are talking about.
While I understand why it might be attractive to think that drivers should be able to hold mathematical models in their head that are able to account for a large number of variables, it's actually not a good idea. Such a calculation is cognitively difficult - even for experienced mathematicians. And any potential benefit will be more than outweighed by the risk of distraction.
The law reflects this - there is no requirement for calculations to be made 'on the fly'. And I cannot see any possibility that a responsible group of lawmakers would think that this would be a good idea.
It would seem to me that the regulations strike a good balance - yes drivers should take time to consider whether the known capabilities of the train are suitable for the route to be taken before starting off. And with a suitable amount of experience of driving, they should be able to detect if something is not working as expected, without having to justify it with a needlessly complicated calculation.
I don't see any possibility of the change you are advocating ever happening.
This is a misunderstanding of the calculations required and their purpose. I can only ever see a need for a driver to carry out two simple calculations for a given journey. Before departure the driver should know what deceleration rate to expect. For multiple units and fixed formation trains this will be known and a calculation is not necessary. For freight and locomotive hauled passenger trains the necessary calculation is specified in the working manual. After departure a running brake test must be carried out a a simple calculation is all that is required to confirm that the required brake performance is achieved. In the very rare occasion that If there is any doubt that the brake performance of the train is less than required the driver can take appropriate action before any risk of an incident occurring.
The incident referred to in the post could have had serious consequences and if being able to determine whether the brake performance of their train is satisfactory avoids one incident then the proposal that drivers should be able to determine that the required performance is achieved has merit.
The incident driver did not correctly assess whether the braking performance of the train was adequate for the maximum speed.
A static brake test alone will not confirm that the train brake performance is adequate for the maximum speed it will operate at.
If people understand the need for a calculation they are much more likely to carry it out diligently.
@niggill617@gma , you may be detecting some scepticism in the replies you are getting. And I note that many of the railway professionals who are on this forum are not engaging with this discussion.
I'm not in the profession, but I am a professional mathematician, and am qualified to read and understand the legislation you are referring to.
I think you are referring to Schedule 4 of the Train Driving Licenses and Certificate Regulations of 2010, which state that "Drivers must be able to check and calculate, before departure, that the train's braking power corresponds to the braking power required for the line, as specified in the vehicle documents." I think the key phrase here is 'before departure'. It means that this is not a calculation based on empirical evidence, but based on the information provided. On that basis, this must therefore be referring to a very simple arithmetical calculation, not the kind of physics based calculations you are talking about.
While I understand why it might be attractive to think that drivers should be able to hold mathematical models in their head that are able to account for a large number of variables, it's actually not a good idea. Such a calculation is cognitively difficult - even for experienced mathematicians. And any potential benefit will be more than outweighed by the risk of distraction.
The law reflects this - there is no requirement for calculations to be made 'on the fly'. And I cannot see any possibility that a responsible group of lawmakers would think that this would be a good idea.
It would seem to me that the regulations strike a good balance - yes drivers should take time to consider whether the known capabilities of the train are suitable for the route to be taken before starting off. And with a suitable amount of experience of driving, they should be able to detect if something is not working as expected, without having to justify it with a needlessly complicated calculation.
I don't see any possibility of the change you are advocating ever happening.
Thank you for a professional polite constructive reply. Yes Schedule 4 and 3 General Professional Knowledge (GPK). So required brake force must be the same as or greater than actual, how many drivers actually could define a force GPK? I don't advocate calculation on the hoof as such. Understand theory and have parameters, not totally some arcane skill. Why was this train class 5, I mean un-braked single pipe? Line speed below 85 mph thus basic rule 60 mph for locomotive, add 144 tonnes swinging; Newton's Second Law smacks me in the face.
Several professionals are sympathetic.
Give me your opinion on Edinburgh, as with Loughborough all highly experienced drivers. Will it take a Public Inquiry and a Judge. Why bring out Schedule 3 amendment if nothing needs to change; GPK?
Schedule 4 of the Train Driving Licenses and Certificate Regulations of 2010, which state that "Drivers must be able to check and calculate, before departure, that the train's braking power corresponds to the braking power required for the line, as specified in the vehicle documents
In the case of the Loughborough south SPAD the calculation was the total train weight and the total available brake force. This would have determined that the maximum speed for the train formation was 45 MPH in accordance with the relevant table in the working manual.
As I pointed out in my post in most instances it is not necessary to carry out any calculations before departure.
In the case of the Loughborough south SPAD the calculation was the total train weight and the total available brake force. This would have determined that the maximum speed for the train formation was 45 MPH in accordance with the relevant table in the working manual.
As I pointed out in my post in most instances it is not necessary to carry out any calculations before departure.
Thank you, I’m beginning to ‘get it’, except what do you mean by the max speed was 45mph?
Why can it only travel ‘upto’ this speed, what would/wouldn’t happen if it travelled at say 60mph?
Surely theses calculations can only be used for freight, how would a passenger driver have any clue at that weight of the train with continually changing ‘cargo’?
Thank you, I’m beginning to ‘get it’, except what do you mean by the max speed was 45mph?
Why can it only travel ‘upto’ this speed, what would/wouldn’t happen if it travelled at say 60mph?
Surely theses calculations can only be used for freight, how would a passenger driver have any clue at that weight of the train with continually changing ‘cargo’?
The calculation for the maximum speed for a train comprising unbraked vehicles has two elements. The lowest calculated speed must apply. The first element to calculate the maximum speed for the train formation is based on the total weight and the available brake force. From the table this is 60 MPH. The other calculation takes the weight of the unbraked portion and the attached vehicles either in front or behind the unbraked portion and its brake force. This is required for the possibility that part of the train brakes away - I realise this is very unlikely but it did happen to a freight train in 2007. From the same table this is 45 MPH. The maximum speed for this formation was the therefore 45MPH and not 75MPH as the driver was told. Another reason for the maximum speed of 45 MPH for this train formation is that if the brakes on the leading or trailing locomotive failed to apply or only one bogie was braked the brake force may not be sufficient to meet the signalling distance at 60 MPH.
if the brake force is not sufficient for the train weight then the train may not stop within the signalling distance as happened at Loughborough.
Multiple units and fixed formation passenger trains are designed to brake at a deceleration rate that will meet the signalling distances at the maximum design speed. Modern passenger vehicles, and indeed many freight wagons have a mechanism that measures the vehicle weight including passengers/goods carried and adjusts the brake force accordingly. For passenger vehicles the deceleration rate wil be the same irrespective of the number of passengers.
This is no longer part of the psychometric testing requirements. Maybe an A-Level in Physics and Maths should be required. I know that Math GCSE is slowly becoming a requirement but maybe Physics should be added too ?
Dunno. I just do it because I'm told to. Normally I'd drinking a cuppa during the FPBT (Full Personal Brake Test) or a minimum DSD (Drivers Safety Device) test that i don't notice the full braking capability of the unit. Maybe this could also be checked with the RAIB to see why this is done and what it is supposed to achieve.
The calculation for the maximum speed for a train comprising unbraked vehicles has two elements. The lowest calculated speed must apply. The first element to calculate the maximum speed for the train formation is based on the total weight and the available brake force. From the table this is 60 MPH. The other calculation takes the weight of the unbraked portion and the attached vehicles either in front or behind the unbraked portion and its brake force. This is required for the possibility that part of the train brakes away - I realise this is very unlikely but it did happen to a freight train in 2007. From the same table this is 45 MPH. The maximum speed for this formation was the therefore 45MPH and not 75MPH as the driver was told. Another reason for the maximum speed of 45 MPH for this train formation is that if the brakes on the leading or trailing locomotive failed to apply or only one bogie was braked the brake force may not be sufficient to meet the signalling distance at 60 MPH.
if the brake force is not sufficient for the train weight then the train may not stop within the signalling distance as happened at Loughborough.
Multiple units and fixed formation passenger trains are designed to brake at a deceleration rate that will meet the signalling distances at the maximum design speed. Modern passenger vehicles, and indeed many freight wagons have a mechanism that measures the vehicle weight including passengers/goods carried and adjusts the brake force accordingly. For passenger vehicles the deceleration rate wil be the same irrespective of the number of passengers.
Mostly because I'm bored, and half a bottle of wine in...
When we do a 'static' brake test, we are testing the system works. We are not testing the braking capability of the train and certainly not calculating *any kind of brake force. You and I drive similar units so we understand that when carrying out the DSD (drivers safety device) check; we are looking for the 'A' fault to appear and that the brake demand shows in emergency (the top section on the HMI (human machine interface)) This confirms to us that the brake is essentially working as designed. Do I need to know the exact braking force ? Christ no. The design specs of the unit takes care of that but I have carried out a test that the unit conforms to the required standard.
Other units I drive have a brake gauge. What I am checking for is that the brake pressure for step 3 corresponds to a 3 bar application. The reality of which is that sometimes I get 3 and a bit and think my unit will be a little bit on the heavy side and sometimes I'm just under and think my brakes will be a little lighter than normal. Because I'm a well trained, underpaid, highly skilled, Driver, and supported by policies and rules etc. I am firmly aware that I need to pull the unit from service if the brake test doesn't conform to certain standards (basically the brake gauge being too far under)
Static brake testing can also check for the silly things like............................................................................. continuity. If the rear unit wasn't couple correctly; I wouldn't be able to release my brakes. It can also check for faults. On my new fangled, sexy modern, unit (like yours) The HMI will show me faults. But in my older units a static brake test can instantly confirm that certain faults are not present. IF I had a 'Brake Control' fault, for example. I wouldn't be able to release the brakes if the MCB (miniature circuit breaker) had tripped in the leading DMOS (Driving Motor Open Standard)
TL;DR (too long, didn't read) - Because my TOC tells me too...
This is no longer part of the psychometric testing requirements. Maybe an A-Level in Physics and Maths should be required. I know that Match GCSE is slowly becoming a requirement but maybe Physics should be added too ?
Dunno. I just do it because I'm told to. Normally I'd drinking a cuppa during the FPBT (Full Personal Brake Test) or a minimum DSD (Drivers Safety Device) test that i don't notice the full braking capability of the unit. Maybe this could also be checked with the RAIB to see why this is done and what it is supposed to achieve.
This is no longer part of the psychometric testing requirements. Maybe an A-Level in Physics and Maths should be required. I know that Match GCSE is slowly becoming a requirement but maybe Physics should be added too ?
Dunno. I just do it because I'm told to. Normally I'd drinking a cuppa during the FPBT (Full Personal Brake Test) or a minimum DSD (Drivers Safety Device) test that i don't notice the full braking capability of the unit. Maybe this could also be checked with the RAIB to see why this is done and what it is supposed to achieve.
@niggill617@gma , you may be detecting some scepticism in the replies you are getting. And I note that many of the railway professionals who are on this forum are not engaging with this discussion.
I'm not in the profession, but I am a professional mathematician, and am qualified to read and understand the legislation you are referring to.
I think you are referring to Schedule 4 of the Train Driving Licenses and Certificate Regulations of 2010, which state that "Drivers must be able to check and calculate, before departure, that the train's braking power corresponds to the braking power required for the line, as specified in the vehicle documents." I think the key phrase here is 'before departure'. It means that this is not a calculation based on empirical evidence, but based on the information provided. On that basis, this must therefore be referring to a very simple arithmetical calculation, not the kind of physics based calculations you are talking about.
While I understand why it might be attractive to think that drivers should be able to hold mathematical models in their head that are able to account for a large number of variables, it's actually not a good idea. Such a calculation is cognitively difficult - even for experienced mathematicians. And any potential benefit will be more than outweighed by the risk of distraction.
The law reflects this - there is no requirement for calculations to be made 'on the fly'. And I cannot see any possibility that a responsible group of lawmakers would think that this would be a good idea.
It would seem to me that the regulations strike a good balance - yes drivers should take time to consider whether the known capabilities of the train are suitable for the route to be taken before starting off. And with a suitable amount of experience of driving, they should be able to detect if something is not working as expected, without having to justify it with a needlessly complicated calculation.
I don't see any possibility of the change you are advocating ever happening.
This Manual contains requirements and other
information for the safe operation of freight trains.
Where tables are referred to these are contained in the
referenced section, for example table E2 is in section E.
Appendices A and B are contained at the end of this
Manual.
Stated : For operational reasons, certain trains have priority in running. To help operating staff, they are grouped into classes; these were formerly identified using letters. When the letter groups were replaced by numerals on 18 June 1962, the classifications became
5.(D) Express freight, livestock, perishable or ballast train with not less than 50 per cent vacuum braked vehicles piped to the engine.
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