Should Train Drivers sit a basic physics examination as part of their training?

[niggill617@gma]

It's possible that there's a key detail that I've missed. In the incident you cite, your analysis disagreed with the official findings in that the incident could have been avoided. Presumably this means that you felt that, had the driver held the brake in Step 5, the train would have stopped on the correct side of the signal, thereby preventing the SPAD. This being the case, surely it would not be the correct thing to have selected Emergency sooner rather than later but rather to have held the brake in a step where control could be maintained.

On the side issue of hitting the red button, I have always been conscious that there may be situations where this is not desirable. If you're out of control and catching something up the last thing you would want it to do is to stop suddenly, which is what would happen if you made a red button call. Under those circumstances I would prefer to make the emergency call via the yellow button.

Split from this thread.

The old adage, " rules are for the guidance of wise men and the blind obedience of fools" regards red and yellow button usage. I guess if in doubt use red, tick the box and satisfy the jury.

When bearing down on a red signal at a rate of knots, emergency is always going to be extremely tempting / desirable. The aim is don't get in that situation in the first place. The braking point of the incident driver would require 67 percent brake power in order to stop, nominal step 4 --- 7.18 percent g mu 0.075. The driver was braking late for a damp day within an area of known low rail adhesion. I don't sit in judgement, what is so wrong is the lack of learning from such incidents.

 

[O L Leigh]

The old adage, " rules are for the guidance of wise men and the blind obedience of fools" regards red and yellow button usage. I guess if in doubt use red, tick the box and satisfy the jury.

The alternative view might be to do whatever gives you best chance at self-preservation to ensure that you're actually around to have the argument in court.

 

[niggill617@gma]

With regards to braking systems, a driver really needs to know how the system(s) operate at each step/mode. Especially if there are differences in operation between different step/modes.

For traction which has regenerative braking, there will be even more differences.

Braking is always about converting kinetic energy (velocity combined with mass) into a different form (heat for conventional brakes). A wheel that is locked due to the brakes applying more force than needed may not be as effective as a wheel that is rotating and transferring energy to the brake pad/shoe or via electro-magnetic means.

And obviously in order for the wheel to rotate while it’s rotation is being resisted by the braking system, it must have enough grip with the surface of the rail.

What you state is so correct. The only thing is physics does not form part of driver training, at least not in any real theoretical form. The saying "me wheels picked up" is no understanding at all. I maintain the industry is non-compliant to legislation, and the whole issue is a can of worms.

== Doublepost prevention - post automatically merged: 26 Feb 2022 ==

The alternative view might be to do whatever gives you best chance at self-preservation to ensure that you're actually around to have the argument in court.

Looks like we are thinking the same thing at the same time.

 

[GC class B1]

The old adage, " rules are for the guidance of wise men and the blind obedience of fools" regards red and yellow button usage. I guess if in doubt use red, tick the box and satisfy the jury.

When bearing down on a red signal at a rate of knots, emergency is always going to be extremely tempting / desirable. The aim is don't get in that situation in the first place. The braking point of the incident driver would require 67 percent brake power in order to stop, nominal step 4 --- 7.18 percent g mu 0.075. The driver was braking late for a damp day within an area of known low rail adhesion. I don't sit in judgement, what is so wrong is the lack of learning from such incidents.

Could you please explain how the values you have quoted have been calculated. From memory I understand that the class 158 and 158 have a three step brake controller, and that the brake retardation at each step is nominally 3%, 6% and 9%g respectively. I don’t think there is a step 4. 67% brake force would require a step 2 brake application which should result in 6%g retardation and would require a minimum wheel/rail coefficient of friction of around 0.065.

 

[rebmcr]

Could you please explain how the values you have quoted have been calculated. From memory I understand that the class 158 and 158 have a three step brake controller, and that the brake retardation at each step is 3%, 6% and 9%g respectively. I don’t think there is a step 4. 67% brake force would require a step 2 brake application which should result in 6%g retardation and would require a minimum wheel/rail coefficient of friction of around 0.065.

I think they are talking about the aforementioned HST SPAD, not the Salisbury collision.

 

[Ediswan]

Braking is always about converting kinetic energy (velocity combined with mass) into a different form (heat for conventional brakes).

It can also be converting gravitational potential energy. Going downhill, brakes might be used to maintain constant velocity, so no change in kinetic energy.

 

[niggill617@gma]

Could you please explain how the values you have quoted have been calculated. From memory I understand that the class 158 and 158 have a three step brake controller, and that the brake retardation at each step is nominally 3%, 6% and 9%g respectively. I don’t think there is a step 4. 67% brake force would require a step 2 brake application which should result in 6%g retardation and would require a minimum wheel/rail coefficient of friction of around 0.065.

Rebmcr is correct. A bit of a side track, but I feel sure a correlation will be obvious between Salisbury and the HST incident. ( lessons not learnt, notwithstanding tribometry is not exact, especially with low clasping force )

HST class 43 and stock-- class 254, 2 plus 8 I think? Has a maximum braking performance of 11 percent g nominal established. Thus with 6 braking steps ( full service and emergency being equal) each step is nominal 1.83 percent g. Therefore step 4 will be nominal 7.3 percent g. Step 3 would be 5.49 percent g nominal. Regarding the HST incident braking point, step 3 would not of stopped the train before red. Step 4 would stop the train well before red. Therefore it has to be step 4, which is 67 percent of maximum, i.e. 4 divided by 6 and multiplied by 100. Step 4 requires mu of about 0.073, which would of done the job. The investigation was incompetent.

The physics I refer to is all over Railway Group Standards. It simply comes down to basic dynamics and kinematics and suvat. These subjects form no part of driver training.

The mathematical physics is not complex, it is simply part of a normal education. A normal education is a requirement of the Train Drivers Licence. I did this level of maths at Secondary Modern in the 70s' RSSB have stated to me " some learners would not have a preference" the ORR stated "half the drivers would not understand". I replied that would include half of the competence managers.

During my time driving class 150/158, the braking performance was subject to nuances , as the engineers experimented with different friction mediums etc. I don't think they are classed as 9 percent g braking traction?

Aside, When assessing braking performance, brake force build up time has to be factored. The extra displacement is subject to the propagation of air and inertia.

The Rail Authorities are not keen on what I advocate even though it is a requirement of law. It all comes down to Corporate Governance and cost risk analysis.

The RAIB have never answered my question regarding Croydon.

Q. 49 percent of the drivers brake at the second tunnel gap; so where do the other 51 percent brake? Why this polarised braking mentality?

A. Not a sausage.

I have also questioned the RAIB on numerous other incidents and they just ignore, or state up is down. I just see it for what it is.

Why wouldn't you be allowed to use the brake gauge? That seems quite odd. I think that every driver knows that it's a display showing the amount of brake force you're applying rather than the rate of deceleration.

I think I'd rather be able to stop a train on the mark than to be able to mathematically calculate braking distances. The formula I use is; what I see out of the window x what I feel through my backside + experience.



My apologies. I didn't spot that in the report.

I wonder what might have happened had the driver stuck with his first impulse.

Remember I did say General Professional Knowledge, not a procedure. I couldn't agree more, intuition first and foremost, backed up with NTS, and finally General Professional Knowledge, as required by law.

The TOC traction 800 user manual, clearly stated the percent gauge is not to be used. All drivers used it anyway. It is no different to a notched step. As you state what you select is not necessarily what you will get.

I remember during training and route learning, some would say "brake at the white house in step 2", others would say" brake at the pink house in step 1", others would say" give it some more, that is why it is there, we might lose time". The actual braking point is 6 percent g in good conditions, notwithstanding average gradient component. During poor conditions, distance should be extended possibly by double to 3 percent g. I drove sprinters before we had sanders, excepting one shot. I never ever had a slide in step 1, with the exception of class 153, step 1 always seemed fierce on the scuds. The coefficient of static friction very rarely goes below 0.03 for any substantial distance. Static friction is grater than kinetic, in other words it takes more to get it sliding than to keep it sliding. Same for the reciprocal.

More often than not, slide protection activates and the consist remains generally in control. I think the system activates within 20 percent of a wheel circumference. This amounts to 100ths of a second. The HST incident had slide activity continually for 17 seconds from commencement of established retarding force. At the 17 second point the ATP data recorded 106.5 mph, and the calculation for selected came out as 106.3 mph.

When constants are constant, theory controls practice. When constants become variable, practice controls theory.

 

[172007]

Remember I did say General Professional Knowledge, not a procedure. I couldn't agree more, intuition first and foremost, backed up with NTS, and finally General Professional Knowledge, as required by law.

The TOC traction 800 user manual, clearly stated the percent gauge is not to be used. All drivers used it anyway. It is no different to a notched step. As you state what you select is not necessarily what you will get.

I remember during training and route learning, some would say "brake at the white house in step 2", others would say" brake at the pink house in step 1", others would say" give it some more, that is why it is there, we might lose time". The actual braking point is 6 percent g in good conditions, notwithstanding average gradient component. During poor conditions, distance should be extended possibly by double to 3 percent g. I drove sprinters before we had sanders, excepting one shot. I never ever had a slide in step 1, with the exception of class 153, step 1 always seemed fierce on the scuds. The coefficient of static friction very rarely goes below 0.03 for any substantial distance. Static friction is grater than kinetic, in other words it takes more to get it sliding than to keep it sliding. Same for the reciprocal.

More often than not, slide protection activates and the consist remains generally in control. I think the system activates within 20 percent of a wheel circumference. This amounts to 100ths of a second. The HST incident had slide activity continually for 17 seconds from commencement of established retarding force. At the 17 second point the ATP data recorded 106.5 mph, and the calculation for selected came out as 106.3 mph.

When constants are constant, theory controls practice. When constants become variable, practice controls theory.

I am really struggling with this "general professional knowledge as required by law" bit. Where does it stupulate this level of knowledge

I know taxi drivers, and Uber Ears delivery riders none of them know the theory and practice of the braking system for their Merc C class and Electric Bicycle. And bus drivers on the forum know the technical details of the friction Co efficient of rubber bus wheel on the varying Tarmac grades and concrete types they encounter on the public roads and how the ABS specifically works when in Snow va dry road.

 

[niggill617@gma]

I am really struggling with this "general professional knowledge as required by law" bit. Where does it stupulate this level of knowledge

I know taxi drivers, and Uber Ears delivery riders none of them know the theory and practice of the braking system for their Merc C class and Electric Bicycle. And bus drivers on the forum know the technical details of the friction Co efficient of rubber bus wheel on the varying Tarmac grades and concrete types they encounter on the public roads and how the ABS specifically works when in Snow va dry road.

Statutory Instrument 1798 is secondary legislation or law. It clearly states understand performance calculation, for all drivers under schedule 3 General Professional Knowledge. The RDG notes details the subject matter, as uploaded.

I know many aviators that have to understand the physics of flight, that is one reason why ATPLs, CPLs are regarded as professional. PPLs also have to pass exams on basic physics, and are trained by the afore mentioned professionals. The recent storm and airliners landing at major airports using crosswind procedure is very much a combination of theory and lots of practice in the sim.

 

[ComUtoR]

Statutory Instrument 1798 is secondary legislation or law. It clearly states understand performance calculation, for all drivers under schedule 3 General Professional Knowledge. The RDG notes details the subject matter, as uploaded.

I'm not sure what you are proposing or claiming. Drivers courses do meet those basic principles. Even looking at your schedule 3 it doesn't ask for much or give specific details.

When you say that the TOC isn't compliant with the law, could you explain where they have failed and highlight or even propose what information you believe is required to meet the legislation please.

I know many aviators that have to understand the physics of flight, that is one reason why ATPLs, CPLs are regarded as professional. PPLs also have to pass exams on basic physics, and are trained by the afore mentioned professionals. The recent storm and airliners landing at major airports using crosswind procedure is very much a combination of theory and lots of practice in the sim.

Are you proposing that Train Drivers sit a basic physics exam or that physics/science GCSE should be a basic requirement ?

 

[niggill617@gma]

I'm not sure what you are proposing or claiming. Drivers courses do meet those basic principles. Even looking at your schedule 3 it doesn't ask for much or give specific details.

When you say that the TOC isn't compliant with the law, could you explain where they have failed and highlight or even propose what information you believe is required to meet the legislation please.



Are you proposing that Train Drivers sit a basic physics exam or that physics/science GCSE should be a basic requirement ?

The RDG notes mention a schedule 3 general professional knowledge exam. What I believe is one day on the drivers course detailing some basic physics would help, eliminate some myth and promote fact. Occupational Psychology has run its course, for the good of the industry, that is proved. Surely some dynamic theory would help in addition. I have already mentioned the requirements of schedule 3 should of been implemented back in 2018 for existing drivers. No such continuation training came my way.

Just to side track a bit; The train planner / driver and the actual driver at Loughborough, would of surely been alerted to the speed error, by simply understanding Newtons Second Law of Motion, in combination with the basic rule book requirements. Two locos and a load of unbraked mass in between. That stands out a country mile. I have never driven a freight train, but I would of picked up on the error straight away, nothing smart or clever about that statement either.



A lawyer has stated to me that things will probably not change, unless there is a major disaster and the Judge orders it. Please explain why so much resistance; its not complex what I highlight.

 

[Steve Harris]

Statutory Instrument 1798 is secondary legislation or law. It clearly states understand performance calculation, for all drivers under schedule 3 General Professional Knowledge. The RDG notes details the subject matter, as uploaded.

I know many aviators that have to understand the physics of flight, that is one reason why ATPLs, CPLs are regarded as professional. PPLs also have to pass exams on basic physics, and are trained by the afore mentioned professionals. The recent storm and airliners landing at major airports using crosswind procedure is very much a combination of theory and lots of practice in the sim.

Back in the day it was called "Theory of Flight". I got learnt it by a ex pilot in 87.

And yes, if you was a pilot you needed to know it and understand it !

 

[GC class B1]

The RDG notes mention a schedule 3 general professional knowledge exam. What I believe is one day on the drivers course detailing some basic physics would help, eliminate some myth and promote fact. Occupational Psychology has run its course, for the good of the industry, that is proved. Surely some dynamic theory would help in addition. I have already mentioned the requirements of schedule 3 should of been implemented back in 2018 for existing drivers. No such continuation training came my way.

Just to side track a bit; The train planner / driver and the actual driver at Loughborough, would of surely been alerted to the speed error, by simply understanding Newtons Second Law of Motion, in combination with the basic rule book requirements. Two locos and a load of unbraked mass in between. That stands out a country mile. I have never driven a freight train, but I would of picked up on the error straight away, nothing smart or clever about that statement either.



A lawyer has stated to me that things will probably not change, unless there is a major disaster and the Judge orders it. Please explain why so much resistance; its not complex what I highlight.

Your point regarding the Loughborough SPAD is interesting although off topic. If the driver had calculated the available brake force from the two locomotives and the total weight of the train he would have determined that the maximum speed in accordance with Table E1 of GO/RT3056 issue 5.1 should have been 45 MPH. GO/RT3056 is the Working Manual for Rail Staff and the applicable table deals with Freight train operations.

 

[ComUtoR]

The RDG notes mention a schedule 3 general professional knowledge exam.

On the portion that you have provided; I see no such statement.

What I believe is one day on the drivers course detailing some basic physics would help

I don't think it would help. Beyond the basic principle of 'apply brake=trains stops' not much else is required. I Don't need a F=MA calculation or a V=IR. It truly isn't required. If you stick the brake in step one at the white house and the train will stop at the platform is a basic understanding and we don't need much more than that. What does happen on a rules course is that they will start to detail other factors involved. Is it snowing ?, Is there low adhesion ?, why we have 'brake regs', use of different braking styles and brake steps. Those are all very much basic physics and meet the current standards of 'understanding the basic principles'

Surely some dynamic theory would help in addition. I have already mentioned the requirements of schedule 3 should of been implemented back in 2018 for existing drivers. No such continuation training came my way.

Sorry but proposing that a Train Driver understands the basics of Newtons Second Law is frankly ludicrous. The Rule Book exists so that those who do understand those Laws of physics tell us Drivers to use the 1 in 5 rule or reduce speed etc.

Picking up a point you mentioned earlier about the 'correct' braking point. Nobody is going to grab a calculator from their bag and try and calculate the exact percentage required for a brake step approaching a station at 50mph with a 32mph crosswind with 700 passengers with an average weight of 70kg, where the station is 975m away on a 1 in 2.875 downhill gradient. No. You just stick it in brake step 1 at the white house.

 

[Annetts key]

I think that drivers off ALLvehicles should be tested to ensure they have a basic understanding of the part of physics dealing with friction and motion.

It’s absolutely clear that most car drivers have no understanding of these, and clearly demonstrate it when due to rain, surface water, mud, oil, snow or ice, they loose control of their vehicles.

But the appropriate authorities won’t do it, because it costs money. So things will only change on when we kill enough people

Oh, and you don’t need a calculator to understand the basic principles…

 

[niggill617@gma]

On the portion that you have provided; I see no such statement.




I don't think it would help. Beyond the basic principle of 'apply brake=trains stops' not much else is required. I Don't need a F=MA calculation or a V=IR. It truly isn't required. If you stick the brake in step one at the white house and the train will stop at the platform is a basic understanding and we don't need much more than that. What does happen on a rules course is that they will start to detail other factors involved. Is it snowing ?, Is there low adhesion ?, why we have 'brake regs', use of different braking styles and brake steps. Those are all very much basic physics and meet the current standards of 'understanding the basic principles'




Sorry but proposing that a Train Driver understands the basics of Newtons Second Law is frankly ludicrous. The Rule Book exists so that those who do understand those Laws of physics tell us Drivers to use the 1 in 5 rule or reduce speed etc.

Picking up a point you mentioned earlier about the 'correct' braking point. Nobody is going to grab a calculator from their bag and try and calculate the exact percentage required for a brake step approaching a station at 50mph with a 32mph crosswind with 700 passengers with an average weight of 70kg, where the station is 975m away on a 1 in 2.875 downhill gradient. No. You just stick it in brake step 1 at the white house.

The RSSB Intelligence analyst told me the issue would divide and mix opinion. I have said before General Professional Knowledge not a procedure. Correct; no one is going to drive a train using a calculator or slide rule ( no battery required).

On the point of basic equations, look at the Loughborough report, 20 mph past the signal for 200 m, do the calculation, what does that tell you? ( that's another debate)

I also have an e mail dated 2013 from the former Office Of Rail Regulation, stating basic physics understanding will be required as part of TDLCR from 2015. The question is why the amendment to the 2010 version; easy answer, to change what was not there before. The now Office of Rail and Road say the understanding is only for EU drivers, yet it is UK secondary legislation.

Perhaps the unfortunate driver at Sandilands and the other 50 percent should brake at the start of the tunnels, using 4 percent g, they would arrive at the correct speed for the curve transit 7 seconds later, compared to the 9 percent g equivalent braking from the second tunnel gap. Should of built a white house.

The knowledge comes before you key in. 100 mph line speed good conditions on the level, the 6 percent g braking point would be 1 mile and 11 chain, allowing for freewheel of 3 seconds. Six percent g is determined during the running brake test. If the average gradient is 1 in a 100 falling the braking point is 1 mile and 28 chain. If the conditions are poor brake at 3 percent g if required, possibly double the distance. This knowledge reinforces what is already written in many PDP booklets. This knowledge also reinforces accountability. These braking points are of course pre- referenced to good land marks as part of route knowledge.

 

[GC class B1]

Rebmcr is correct. A bit of a side track, but I feel sure a correlation will be obvious between Salisbury and the HST incident. ( lessons not learnt, notwithstanding tribometry is not exact, especially with low clasping force )

HST class 43 and stock-- class 254, 2 plus 8 I think? Has a maximum braking performance of 11 percent g nominal established. Thus with 6 braking steps ( full service and emergency being equal) each step is nominal 1.83 percent g. Therefore step 4 will be nominal 7.3 percent g. Step 3 would be 5.49 percent g nominal. Regarding the HST incident braking point, step 3 would not of stopped the train before red. Step 4 would stop the train well before red. Therefore it has to be step 4, which is 67 percent of maximum, i.e. 4 divided by 6 and multiplied by 100. Step 4 requires mu of about 0.073, which would of done the job. The investigation was incompetent.

The physics I refer to is all over Railway Group Standards. It simply comes down to basic dynamics and kinematics and suvat. These subjects form no part of driver training.

The mathematical physics is not complex, it is simply part of a normal education. A normal education is a requirement of the Train Drivers Licence. I did this level of maths at Secondary Modern in the 70s' RSSB have stated to me " some learners would not have a preference" the ORR stated "half the drivers would not understand". I replied that would include half of the competence managers.

During my time driving class 150/158, the braking performance was subject to nuances , as the engineers experimented with different friction mediums etc. I don't think they are classed as 9 percent g braking traction?

Aside, When assessing braking performance, brake force build up time has to be factored. The extra displacement is subject to the propagation of air and inertia.

The Rail Authorities are not keen on what I advocate even though it is a requirement of law. It all comes down to Corporate Governance and cost risk analysis.

The RAIB have never answered my question regarding Croydon.

Q. 49 percent of the drivers brake at the second tunnel gap; so where do the other 51 percent brake? Why this polarised braking mentality?

A. Not a sausage.

I have also questioned the RAIB on numerous other incidents and they just ignore, or state up is down. I just see it for what it is.


Remember I did say General Professional Knowledge, not a procedure. I couldn't agree more, intuition first and foremost, backed up with NTS, and finally General Professional Knowledge, as required by law.

The TOC traction 800 user manual, clearly stated the percent gauge is not to be used. All drivers used it anyway. It is no different to a notched step. As you state what you select is not necessarily what you will get.

I remember during training and route learning, some would say "brake at the white house in step 2", others would say" brake at the pink house in step 1", others would say" give it some more, that is why it is there, we might lose time". The actual braking point is 6 percent g in good conditions, notwithstanding average gradient component. During poor conditions, distance should be extended possibly by double to 3 percent g. I drove sprinters before we had sanders, excepting one shot. I never ever had a slide in step 1, with the exception of class 153, step 1 always seemed fierce on the scuds. The coefficient of static friction very rarely goes below 0.03 for any substantial distance. Static friction is grater than kinetic, in other words it takes more to get it sliding than to keep it sliding. Same for the reciprocal.

More often than not, slide protection activates and the consist remains generally in control. I think the system activates within 20 percent of a wheel circumference. This amounts to 100ths of a second. The HST incident had slide activity continually for 17 seconds from commencement of established retarding force. At the 17 second point the ATP data recorded 106.5 mph, and the calculation for selected came out as 106.3 mph.

When constants are constant, theory controls practice. When constants become variable, practice controls theory.

I have calculated the theoretical stoping distances at different speeds for several designs of rolling stock and train formations. The applicable BS EN document specifies a formula that as well as the parameters you have mentioned (vehicle mass, brake application time, actuator output and mechanical advantage of the rigging including the ratio of brake disc effective diameter and wheel diameter where disc brakes are concerned) it also includes kinematic energy of the rotating elements and train rolling resistance, and the variables of brake pad or block material coefficient of friction, and most importantly the rigging efficiency. At each specific speed and brake actuator output force the coefficient of friction varies. For composition materials used in brake pads this variation is not large but is still significant. For cast iron the variation in coefficient of friction is large. The rigging efficiency will vary with the maintenance condition of the bogie and can have a noticeable difference in the retardation rate achieved. The result is that the braking performance achieved will probably vary significantly from the theoretical values. It therefore seems unrealistic to expect drivers to assess the braking performance using calculated values but should base their assessment on experience and the running brake test. I can agree however that it is good practice for drivers to understand the principles of brake systems and the factors that determine the stopping distance.

With regard the the HST values you have discussed, I have two points to add.
1. GW HST vehicles have been modified to provide a different braking rate between the power cars and the trailer vehicles in all brake steps below Full Service. Full Service and Emergency brake rates as you correctly state are the same and provide the same nominal retardation rate for all vehicles.
2. The original WSP system fitted to HST vehicles was basic and unreliable and it would not be surprising to find that it did not prevent wheel slide.

 

[niggill617@gma]

I have calculated the theoretical stoping distances at different speeds for several designs of rolling stock and train formations. The applicable BS EN document specifies a formula that as well as the parameters you have mentioned (vehicle mass, brake application time, actuator output and mechanical advantage of the rigging including the ratio of brake disc effective diameter and wheel diameter where disc brakes are concerned) it also includes kinematic energy of the rotating elements and train rolling resistance, and the variables of brake pad or block material coefficient of friction, and most importantly the rigging efficiency. At each specific speed and brake actuator output force the coefficient of friction varies. For composition materials used in brake pads this variation is not large but is still significant. For cast iron the variation in coefficient of friction is large. The rigging efficiency will vary with the maintenance condition of the bogie and can have a noticeable difference in the retardation rate achieved. The result is that the braking performance achieved will probably vary significantly from the theoretical values. It therefore seems unrealistic to expect drivers to assess the braking performance using calculated values but should base their assessment on experience and the running brake test. I can agree however that it is good practice for drivers to understand the principles of brake systems and the factors that determine the stopping distance.

With regard the the HST values you have discussed, I have two points to add.
1. GW HST vehicles have been modified to provide a different braking rate between the power cars and the trailer vehicles in all brake steps below Full Service. Full Service and Emergency brake rates as you correctly state are the same and provide the same nominal retardation rate for all vehicles.
2. The original WSP system fitted to HST vehicles was basic and unreliable and it would not be surprising to find that it did not prevent wheel slide.

Thanks for the reply, engineers are always forgotten, yet form the back bone of rail operations.

The driver assessment of brake performance should not come from gut feeling alone, although it is of course very pertinent. I always braked HST with step 2 away from appendix C locations. Nominal 0.367 m/s/s. My brake test would be on straight level track. I would select initial for a few seconds and then step 2. After about 4 seconds the retarding force would be felt. I would time a 10 mph reduction, I would expect 12 seconds. Notwithstanding empirical error it was always close, never had a rejection, always appreciated. As I got close to the 125 mph appendix C zone, I would do another brake test using step 4, the time expected would be about 6 seconds, again never had a rejection. These running brake tests proved my braking points, and the excellent maintenance of the systems. The theory pretty much matched the practice. The principle of slowing down should not be arcane. The WSP made a lot of noise but always did the job.

Refer to RAIB report 02/2011 paragraph 26.

60 seconds to slow by 6 mph, gut feeling failed, theory would of saved the day. I could refer you to several other examples.

On your point 1, surely it makes no difference, from the drivers perspective, from the seat its the sum of the whole system, simply a rate of deceleration.

 

[GC class B1]

Thanks for the reply, engineers are always forgotten, yet form the back bone of rail operations.

The driver assessment of brake performance should not come from gut feeling alone, although it is of course very pertinent. I always braked HST with step 2 away from appendix C locations. Nominal 0.367 m/s/s. My brake test would be on straight level track. I would select initial for a few seconds and then step 2. After about 4 seconds the retarding force would be felt. I would time a 10 mph reduction, I would expect 12 seconds. Notwithstanding empirical error it was always close, never had a rejection, always appreciated. As I got close to the 125 mph appendix C zone, I would do another brake test using step 4, the time expected would be about 6 seconds, again never had a rejection. These running brake tests proved my braking points, and the excellent maintenance of the systems. The theory pretty much matched the practice. The principle of slowing down should not be arcane. The WSP made a lot of noise but always did the job.

Refer to RAIB report 02/2011 paragraph 26.

60 seconds to slow by 6 mph, gut feeling failed, theory would of saved the day. I could refer you to several other examples.

Thank you for mentioning this incident report. I have read many more recent RAIB reports as I find them a useful source of information as well as being of general interest, but I don’t recall reading this particular report. Your point about non compliance with the requirements for running brake tests and a failure to recognise that the deceleration achieved was insufficient should have raised a concern that the performance of the train braking was inadequate. Bringing the train to a stand as soon as this became apparent would have prevented the SPAD.
In my opinion you may be right that had the driver concerned understood what deceleration should have resulted from the brake application requested he would have realised that the brake retardation requested by the Driver’s Brake controller had not been achieved and therefore the train brake performance was very poor. However I can appreciate that the failure to carry out a running brake test is a separate issue to consciously assessing the brake performance when he was preparing to stop at a red signal which was some distance away. He was probably not consciously assessing the braking performance but was thinking of other things.
in summary I agree that it is important for drivers to continually be alert to possible problems with their train. However while it should not require drivers to understand how the brake system works in order to identify a potential problem, the more understanding a driver has about the brake system the more likely he will be to recognise a problem. I have always believed that if people understand why an instruction exists the more likely they are to follow it rather than see it as unnecessary or an imposition from someone who doesn’t understand their requirements. This could apply to the running brake test where rather than the temptation to see is as another stupid or unnecessary instruction, understanding why it is required will increase compliance and help ensure that it achieves the intended result.

 

[niggill617@gma]

Thank you for mentioning this incident report. I have read many more recent RAIB reports as I find them a useful source of information as well as being of general interest, but I don’t recall reading this particular report. Your point about non compliance with the requirements for running brake tests and a failure to recognise that the deceleration achieved was insufficient should have raised a concern that the performance of the train braking was inadequate. Bringing the train to a stand as soon as this became apparent would have prevented the SPAD.
In my opinion you may be right that had the driver concerned understood what deceleration should have resulted from the brake application requested he would have realised that the brake retardation requested by the Driver’s Brake controller had not been achieved and therefore the train brake performance was very poor. However I can appreciate that the failure to carry out a running brake test is a separate issue to consciously assessing the brake performance when he was preparing to stop at a red signal which was some distance away. He was probably not consciously assessing the braking performance but was thinking of other things.
in summary I agree that it is important for drivers to continually be alert to possible problems with their train. However while it should not require drivers to understand how the brake system works in order to identify a potential problem, the more understanding a driver has about the brake system the more likely he will be to recognise a problem. I have always believed that if people understand why an instruction exists the more likely they are to follow it rather than see it as unnecessary or an imposition from someone who doesn’t understand their requirements. This could apply to the running brake test where rather than the temptation to see is as another stupid or unnecessary instruction, understanding why it is required will increase compliance and help ensure that it achieves the intended result.

A professional and measured response indeed. We posters often get carried away with our opinions and chests puff out.

I have been engaged with Rail Authorities for a number of years regarding elementary physics, often resulting in hostility. Unfortunately when making a point it seems like I critique other drivers. The fact is I believe in a just culture; learn from previous mistakes, thus a drivers pride maybe a necessary sacrifice, as long as it is not a punishment. Everyone is capable of cognitive mistakes.

What is your opinion on the Loughborough SPAD RAIB 10/2020. I find it it full of flaws, for example:

1. Figure 7 the bar chart, makes no sense. ( note it includes 15 seconds freewheel from RAIB email)

2. Page 7 20 mph past the signal for 200 m equals 0.199 m/s/s.

3. 50 percent of what it should be, conclusions from that? See fig 7 on RAIB report. 73 mph distance bar plot full service, minus 15 s worth of freewheel, use some suvat maths and we have 0.45 m/s/s. The train passes the signal at 20 mph and stops 200 m later. That is a rate of 0.199 m/s/s, half that of the bar chart full service illustration. Does not compute.

 

[GC class B1]

A professional and measured response indeed. We posters often get carried away with our opinions and chests puff out.

I have been engaged with Rail Authorities for a number of years regarding elementary physics, often resulting in hostility. Unfortunately when making a point it seems like I critique other drivers. The fact is I believe in a just culture; learn from previous mistakes, thus a drivers pride maybe a necessary sacrifice, as long as it is not a punishment. Everyone is capable of cognitive mistakes.

What is your opinion on the Loughborough SPAD RAIB 10/2020. I find it it full of flaws, for example:

1. Figure 7 the bar chart, makes no sense. ( note it includes 15 seconds freewheel from RAIB email)

2. Page 7 20 mph past the signal for 200 m equals 0.199 m/s/s.

3. 50 percent of what it should be, conclusions from that?

1. The bar chart does make sense but is not easy to read.
2. you are correct the deceleration rate is about 2% g which is the not surprising as the EMU is unbraked. Note that as I posted earlier the maximum speed for this train should have been 45MPH
3. As point 2 above.

 

[irish_rail]

Glad to see retirement hasn't dampened your passion for this subject buddy.

 

[niggill617@gma]

On the portion that you have provided; I see no such statement.




I don't think it would help. Beyond the basic principle of 'apply brake=trains stops' not much else is required. I Don't need a F=MA calculation or a V=IR. It truly isn't required. If you stick the brake in step one at the white house and the train will stop at the platform is a basic understanding and we don't need much more than that. What does happen on a rules course is that they will start to detail other factors involved. Is it snowing ?, Is there low adhesion ?, why we have 'brake regs', use of different braking styles and brake steps. Those are all very much basic physics and meet the current standards of 'understanding the basic principles'




Sorry but proposing that a Train Driver understands the basics of Newtons Second Law is frankly ludicrous. The Rule Book exists so that those who do understand those Laws of physics tell us Drivers to use the 1 in 5 rule or reduce speed etc.

Picking up a point you mentioned earlier about the 'correct' braking point. Nobody is going to grab a calculator from their bag and try and calculate the exact percentage required for a brake step approaching a station at 50mph with a 32mph crosswind with 700 passengers with an average weight of 70kg, where the station is 975m away on a 1 in 2.875 downhill gradient. No. You just stick it in brake step 1 at the white house.

The Stafford report is another example of not understanding Newtons Second law.

1. No consideration to loco rule book speed constraints.
2. 1 in 5 would not apply.
3. Basic slap in the face physics would of saved the day. F =ma

A bit like some electrician not understanding V=IR, I don't suppose such a tradesman exists, would of failed a test job (am1 and 2) or their City and Guilds.

Many Euro countries require their drivers to have gained technical or scientific qualifications to a high level. U.K. believed this unnecessary, which I think is correct. Drivers don't really require any high level of academic achievement, unless destined for the top. The general professional knowledge bit, is just what it says on the tin.

What I proposed to RSSB back in 2013 really is not difficult, and would cost very little. The benefits of NTS have plateaued, so why not try something new.

The intelligence analyst did say it would be a hazardous path to take though, not sure why; he never really explained that statement. Might of been a little knowledge is dangerous doctrine.

== Doublepost prevention - post automatically merged: 1 Mar 2022 ==

Glad to see retirement hasn't dampened your passion for this subject buddy.

Dammit! my cover is blown.

 

[niggill617@gma]

On the portion that you have provided; I see no such statement.




I don't think it would help. Beyond the basic principle of 'apply brake=trains stops' not much else is required. I Don't need a F=MA calculation or a V=IR. It truly isn't required. If you stick the brake in step one at the white house and the train will stop at the platform is a basic understanding and we don't need much more than that. What does happen on a rules course is that they will start to detail other factors involved. Is it snowing ?, Is there low adhesion ?, why we have 'brake regs', use of different braking styles and brake steps. Those are all very much basic physics and meet the current standards of 'understanding the basic principles'




Sorry but proposing that a Train Driver understands the basics of Newtons Second Law is frankly ludicrous. The Rule Book exists so that those who do understand those Laws of physics tell us Drivers to use the 1 in 5 rule or reduce speed etc.

Picking up a point you mentioned earlier about the 'correct' braking point. Nobody is going to grab a calculator from their bag and try and calculate the exact percentage required for a brake step approaching a station at 50mph with a 32mph crosswind with 700 passengers with an average weight of 70kg, where the station is 975m away on a 1 in 2.875 downhill gradient. No. You just stick it in brake step 1 at the white house.

Please note attachment annex 2, regards missing statement.

 

[Peter Sarf]

What I don't get is how can a train driver use the formulae some think should be in their training to drive safely if they have no idea what the actual VALUE of the coefficient of friction is on a particular stretch of line.

A driver of a vehicle needs to know what affect friction or a degradation of it does to braking distances but only in an approximate way. But not how to calculate the exact stopping distance.

Has a train driver really got the time to do a calculation of likely stopping distance even if the coefficient of friction was miraculously actually known at every point on the line ?.

In the case of this accident the poor driver did not know how poor the coefficient of friction was. The driver could have driven more cautiously but would have had do so for the entire route. And on several days or weeks. What effect would this have had on reliability of the service and all the other services ?. It is my feeling that the chances of this type of accident happening are so very low that it is hard to justify the caution required. And it is only hindsight that shows this up.

What is needed is some magic way of letting the driver know roughly how slippery it is OR to more reliably avoid the tracks being so slippery OR have a better system for stopping a train on slippery rail. Much of which has been discussed up thread.

I know little of train driving. But I did get to university to read Nuclear Physics - but so what.

 

[TheEdge]

A driver of a vehicle needs to know what affect friction or a degradation of it does to braking distances but only in an approximate way. But not how to calculate the exact stopping distance.

Has a train driver really got the time to do a calculation of likely stopping distance even if the coefficient of friction was miraculously actually known at every point on the line ?.

This is the point that's been made over and over again but the poster just refers back to his statutory document and some personal crusade to get us all in the classroom to be able to reel off the formulae behind braking. Rather than just the act of slowing a train down in a controlled fashion.

In the case of this accident the poor driver did not know how poor the coefficient of friction was. The driver could have driven more cautiously but would have had do so for the entire route. And on several days or weeks. What effect would this have had on reliability of the service and all the other services ?. It is my feeling that the chances of this type of accident happening are so very low that it is hard to justify the caution required. And it is only hindsight that shows this up.

We do this to an extent in Autumn and every year the railways get called out for always being delayed and blaming it on those leaves on the line then being told that's not a real excuse. But as you correctly say its impossible to do that perfectly every time and every year someone will make a mistake. 99% of the time its nothing more than a station overrun or maybe a SPAD (that often get exonerated because its well known that sometimes there really isn't much a driver can do), but sadly occasionally its worse.

What is needed is some magic way of letting the driver know roughly how slippery it is OR to more reliably avoid the tracks being so slippery OR have a better system for stopping a train on slippery rail. Much of which has been discussed up thread.

We have a lot of this and it comes from experience. For me personally in autumn I brake early. I know my rolling stock, if the pneumatic brake kicks in I know the WSP is activating but isn't intervening too much, if the pneumatic brake readout looks like its performing cadence braking I know the WSP is working hard, if my speedo starts wiggling then I know the WSP is trying but I'm beginning to slide and if the speedo drops to zero I know I'm sliding. I don't need to be calculating anything mathematical. Modern WSP that's coming along with brand new stock is pretty tremendous and would quite possibly have stopped this incident from happening.

I know little of train driving. But I did get to university to read Nuclear Physics - but so what.

At the risk of adding 1 + 1 and getting 3 I wonder how many people working in the control room of a nuclear plant can truly do the maths related to what's going on in the reactor as opposed to working with the data provided to them by control equipment and an understanding of what is happening, what should be happening and the broad strokes of what is going on in the core?

 

[Need2]

In answer to the title of this thread,
No, no and thrice no!
Why would a driver of any wheeled vehicle need to know any of it?
Simply poppycock.

 

[seagull]

AFAIK new trainee drivers already do in the form of Level 2 Mathematics Functional Skills. Nothing more than that is necessary or desirable: drivers are employed for abilities other than becoming obsessed with academic or theoretical detail while in the process of carrying out a safety-critical task.

 

[niggill617@gma]

AFAIK new trainee drivers already do in the form of Level 2 Mathematics Functional Skills. Nothing more than that is necessary or desirable: drivers are employed for abilities other than becoming obsessed with academic or theoretical detail while in the process of carrying out a safety-critical task.

Thank you for your input.

With consideration to the running brake test re RAIB report 5/2020 Edinburgh Sleeper. In my interpretation from the time trace, the brake application lasted about 26 seconds, with about 50 percent selected, 11 mph reduction in speed, level gradient. Therefore a deceleration of about 0.189 m/s/s. Had the coaches been providing braking effort the rate would be about 0.45 m/s/s. The speed reduction would be around 23 mph.

I dispute the dynamic brake masked the isolation of the 8 coaches. If the driver had received continuation training, he would of identified the earlier error. The whole concept of running brake tests is called into question here. The driver's feel or sense of inertia failed.

Looking forward to constructive polite counter debate, and happy to be corrected.

 

[Peter Sarf]

.........

At the risk of adding 1 + 1 and getting 3 I wonder how many people working in the control room of a nuclear plant can truly do the maths related to what's going on in the reactor as opposed to working with the data provided to them by control equipment and an understanding of what is happening, what should be happening and the broad strokes of what is going on in the core?

That is a rather good analogy. It springs to my mind that the detailed mathematical calculations are done at design stage and that once the power station or train is built and tested it is then left for the operators/drivers to continue with a reasonable understanding of the Physics involved.

AFAIK new trainee drivers already do in the form of Level 2 Mathematics Functional Skills. Nothing more than that is necessary or desirable: drivers are employed for abilities other than becoming obsessed with academic or theoretical detail while in the process of carrying out a safety-critical task.

Yes the driver has to get out there and deal with the vagaries of the real world.