Driving styles with flashing yellows

[MichaelAMW]

This is a question arising from my observations, looking out of the window, of HSTs approaching Didcot on the down main, taking the 70 mph crossovers to the down relief and then turning onto the avoiding line to head towards Oxford.

I am interested in why different drivers begin to slow down at different points.

In terms of various distances (Some slight rounding)

Single flashing yellow to junction signal to cross DM to DR 1208 yds
From junction single DM to DR, to junction signal for Oxford line 1343 yds
HST Stopping distance from 125 mph 1750yds
HST stopping distance from 70 mph 650 yds
Thus braking distance 125 to 70 mph 1100 yds

So, it seems to me, if the driver of an HST following this route began a normal braking application at the single flashing then the speed will be down to 70 mph by the junction signal on the down main and, if the junction signal doesn't clear up from a single yellow with the route indicator, there is enough distance to stop by the next signal, the junction signal for the Oxford line.

Finally the question: why do some drivers start braking at the double flashing yellow, bringing the speed down to approx 70 mph by the single flashing yellow and then coasting from there. They could safely keep at 125 mph until the single flashing yellow - and some indeed do so. It seems a waste of the benefit available from the infrastructure and could delay trains behind.

My sources:
http://www.rssb.co.uk/SiteCollectionDocuments/pdf/reports/research/T060j_rpt_final.pdf
http://www.signallingnotices.org.uk/scans/161/1994 - 65 Didcot.pdf

 

[notadriver]

Its called defensive and professional driving.

 

[MichaelAMW]

Its called defensive and professional driving.

Not quite sure what "professional" means in this situation. And what would defensive and professional driving consist of?

I was asking why there is a significant variation in the approach taken, so are you hinting that some of the drivers are driving incorrectly? More than the full braking distance is available here from the single flashing yellow and in nearly all cases when a driver is approaching a red there is only that full braking distance and not much more. The extra 1000+ yds of warning you get from the flashing double yellow therefore can't be vital as most of the time a driver is expected to be able to stop without all that extra distance to play with.

 

[notadriver]

Professional means adhering to the professional driving policy for the particular TOC in question. Variations might occur because all drivers are human beings and do things slightly differently as they are not machines?

 

[Cherry_Picker]

It depends on lots of things. Type of traction is the biggest, but you have drivers who brake light and early, drivers who brake heavier and later, drivers who kill a bit of speed initially and coast before fine tuning nearer the speed restriction. As long as it is safe and keeps time then I don't think that any one way is superior to another.

 

[The Planner]

In our experience FGW are the heaviest users for want of a better phrase of "professional" driving, it has certainly required us to inflate running times in a lot of cases.

 

[TOCDriver]

It depends on lots of things. Type of traction is the biggest, but you have drivers who brake light and early, drivers who brake heavier and later, drivers who kill a bit of speed initially and coast before fine tuning nearer the speed restriction. As long as it is safe and keeps time then I don't think that any one way is superior to another.

Absolutely spot on. I tend to be the lighter and earlier brigade though simply because I was trained and guided that way. Plus, that's a more defensive method against wheel slip in my opinion

 

[westcoaster]

Going past a single flashing yellow at 125 mph your having a laugh right, for me it's half the line speed past the single flashing yellow (after all the otmr does not know the difference between a flashing yellow and a steady one) .

 

[TOCDriver]

Going past a single flashing yellow at 125 mph your having a laugh right, for me it's half the line speed past the single flashing yellow (after all the otmr does not know the difference between a flashing yellow and a steady one) .

Yeah, but you drive monsters! 125mph past a single flashing yellow, in any traction, is a bit stupid. Unless you have done it, I don't think people know how difficult and risky breaking a very heavy machine on metal to metal surfaces really is

 

[455driver]

(after all the otmr does not know the difference between a flashing yellow and a steady one) .

The OTMR doesnt know the difference between red, yellow or double yellow, but the forward facing camera does!
--- old post above --- --- new post below ---

Single flashing yellow to junction signal to cross DM to DR 1208 yds
From junction single DM to DR, to junction signal for Oxford line 1343 yds
HST Stopping distance from 125 mph 1750yds
HST stopping distance from 70 mph 650 yds
Thus braking distance 125 to 70 mph 1100 yds

Are these normal, full service or emergency braking distances, do they allow for variations in the adhesion available at the wheels etc etc.

 

[Teaboy1]

Interesting data but when you say stopping distance, do you discriminate between normal progressive gentile stops ... or is E-STOP that with soup/tea/coffee in yer lap?? Yes I know locked wheels will put a flat on the tyres and E-STOPS should not happen with good driving/signalling etc .

 

[O L Leigh]

I'm afraid that your assumptions are based on data that cannot actually be used to assess the braking capabilities of any given train.

The research is into the percentage of adhesion is required for braking and whether there has been an increasing trend with newer rolling stock. It contains no information about the methodology or how the data was arrived at and takes no account of track conditions, differences in driving styles and so on. Therefore I would have to say that the braking curves provided should be treated with great caution and probably shouldn't be applied to real life situations.

As for differences in driving styles, well that is affected by so many variables that it is almost impossible to give full explanations. However, some of the major ones have already been touched on. Defensive driving (driving in such a way as to reduce the chances of an operating incident) and professional driving (which includes energy efficiency and driving smoothly to avoid heavy stops) have a role to play.

The other thing is that you just don't know what is going to happen with the signals ahead. The normal signal sequence for junctions with flashing yellow signals is that the junction signal will be one yellow and you cannot assume that it will clear on approach no matter how often it does. Therefore you have to drive in such a way as to be capable of stopping safely and smoothly at the first signal on the diverging line.

No matter what the capability of the track and train, any driver who regularly comes steaming up to a junction at 125mph and then throws in the anchors to get it down to 70mph for the junction itself when facing a single yellow and a red around the corner is going to be having a chat with the gaffer.

Whether or not you feel it's possible you're not in a position of responsibility with regard to the train, the people on it, the track it runs on and your own livelihood. You have a comfy seat and a window and can sit back and watch in comfort. Each driver will deal with the junction differently, but we're all professional enough to know what we need to consider when faced with situations like this.

O L Leigh

 

[notadriver]

Very nice post O L Leigh +1 !!

 

[TDK]

This is a question arising from my observations, looking out of the window, of HSTs approaching Didcot on the down main, taking the 70 mph crossovers to the down relief and then turning onto the avoiding line to head towards Oxford.

I am interested in why different drivers begin to slow down at different points.

In terms of various distances (Some slight rounding)

Single flashing yellow to junction signal to cross DM to DR 1208 yds
From junction single DM to DR, to junction signal for Oxford line 1343 yds
HST Stopping distance from 125 mph 1750yds
HST stopping distance from 70 mph 650 yds
Thus braking distance 125 to 70 mph 1100 yds

When you say stopping distances is this with an emergency brake application?

So, it seems to me, if the driver of an HST following this route began a normal braking application at the single flashing then the speed will be down to 70 mph by the junction signal on the down main and, if the junction signal doesn't clear up from a single yellow with the route indicator, there is enough distance to stop by the next signal, the junction signal for the Oxford line.

Sorry but I am afraid you do not have clue about driving trains, I know you are asking a question here but the reason why the driver does not do this is because he/she wants to keep their £45k year job

Finally the question: why do some drivers start braking at the double flashing yellow, bringing the speed down to approx 70 mph by the single flashing yellow and then coasting from there. They could safely keep at 125 mph until the single flashing yellow - and some indeed do so. It seems a waste of the benefit available from the infrastructure and could delay trains behind.

Why do some drivers of a car use their gears to slow their car and some heavy braking? Driving a train has many parameters and a list is below!

1. Safety (passing a single yellow at 125mph is not safe)
2. Customer comfort
3. Timings (if you are on time does it matter what speed you are doing?)
4. Professional driving polcy (the train driver bible)
5. Carbon foot print (eco driving is a big thing nowadays)
6. Common sence

Firstly how do you know how fast the train travelling looking out the window, secondly driving in this manner is not going to save any time due to the fact that if you slow the train to 70 and then apply power the amps will have already built up for the traction motors and therefore you will acceelerate quicker from the junction.

Look up some posts on Professional Driving Polocies and then you may understand a little more

 

[Laryk]

The other thing is that you just don't know what is going to happen with the signals ahead. The normal signal sequence for junctions with flashing yellow signals is that the junction signal will be one yellow and you cannot assume that it will clear on approach no matter how often it does. Therefore you have to drive in such a way as to be capable of stopping safely and smoothly at the first signal on the diverging line.

Wasn't there an incident at the junction being discussed where a driver did assume the signal would clear and ended up passing the following signal at red?

Edit: Yes, there was. RAIB

 

[Kneedown]

I'm afraid that your assumptions are based on data that cannot actually be used to assess the braking capabilities of any given train.

The research is into the percentage of adhesion is required for braking and whether there has been an increasing trend with newer rolling stock. It contains no information about the methodology or how the data was arrived at and takes no account of track conditions, differences in driving styles and so on. Therefore I would have to say that the braking curves provided should be treated with great caution and probably shouldn't be applied to real life situations.

As for differences in driving styles, well that is affected by so many variables that it is almost impossible to give full explanations. However, some of the major ones have already been touched on. Defensive driving (driving in such a way as to reduce the chances of an operating incident) and professional driving (which includes energy efficiency and driving smoothly to avoid heavy stops) have a role to play.

The other thing is that you just don't know what is going to happen with the signals ahead. The normal signal sequence for junctions with flashing yellow signals is that the junction signal will be one yellow and you cannot assume that it will clear on approach no matter how often it does. Therefore you have to drive in such a way as to be capable of stopping safely and smoothly at the first signal on the diverging line.

No matter what the capability of the track and train, any driver who regularly comes steaming up to a junction at 125mph and then throws in the anchors to get it down to 70mph for the junction itself when facing a single yellow and a red around the corner is going to be having a chat with the gaffer.

Whether or not you feel it's possible you're not in a position of responsibility with regard to the train, the people on it, the track it runs on and your own livelihood. You have a comfy seat and a window and can sit back and watch in comfort. Each driver will deal with the junction differently, but we're all professional enough to know what we need to consider when faced with situations like this.

O L Leigh

Not a great deal more i can add to this, other than to say another +1 to O L Leigh.
Very well put.

 

[MichaelAMW]

Thanks for the replies - apart from the faintly patronising ones from the drivers. I simply asked a question and it was not a stupid question, so I was after your expertise. There are piles of information in the "public domain" and it is not exceptionally hard to digest.

Too many things to quote so a couple of things in reply.

I haven't suggested that any driver has approached a single yellow at 125. I certainly haven't implied in any way that I have seen any driving that was apparently assuming the junction signal would clear up from a single yellow with a route indicator. And neither am I even speculating - I am telling you what I have observed. I said that from the single *flashing* yellow there is more than full braking distance to the first signal that would be at red. In other situations, as I commented, such as on plain line, they would have no more distance than that from the first warning, i.e the double yellow, in which to stop. Whatever actual practice is, I am sure that a normal service braking started at the single flashing yellow would bring the speed down to 70 in good time for the junction and down to zero if necessary by the following signal, should that remain at red. I am certain - because it is merely factual - that braking at the flashing double yellow is a considerably more cautious practice than would occur in most other situations approaching a red. The HST can - and has to - stop in the space of two signal sections in a four-aspect area and I merely wanted to know why some drivers' style at a high-speed junction was consistent with this and for some it isn't. About half the times I have observed, the train has been under power until the single flashing yellow and this has not required excessive braking or preventing the train stopping at the following signal on the occasions when it has been red.

The data for the braking distances is for normal braking and seems quite well researched but you could argue it's only supporting evidence. The braking distance for the HST, whatever other detail you might wish to add, has to be no more than the length of two signal sections, which round there is 2000 yds ish.

 

[O L Leigh]

Thanks for the replies - apart from the faintly patronising ones from the drivers. I simply asked a question and it was not a stupid question, so I was after your expertise. There are piles of information in the "public domain" and it is not exceptionally hard to digest.

Apologies if it seemed patronising, but you asked for our expertise and it was given. I can't speak for any of my other colleagues, but I found your framing of the question slightly patronising. It felt very much as though you were questioning the professionalism of drivers, our route knowledge, train handling skills and our ability to weigh up all the factors and come up with a braking technique that is safe, appropriate and comfortable.

I haven't suggested that any driver has approached a single yellow at 125. I certainly haven't implied in any way that I have seen any driving that was apparently assuming the junction signal would clear up from a single yellow with a route indicator. And neither am I even speculating - I am telling you what I have observed.

Fair enough. However, what you are suggesting is that drivers are braking sooner than you feel is necessary.

I said that from the single *flashing* yellow there is more than full braking distance to the first signal that would be at red. In other situations, as I commented, such as on plain line, they would have no more distance than that from the first warning, i.e the double yellow, in which to stop.

This is perhaps true. But equally, if I know that I am going to have to slow down for something like a speed restriction up ahead, then I may shut off power in good time and brake very gently down.

Whatever actual practice is, I am sure that a normal service braking started at the single flashing yellow would bring the speed down to 70 in good time for the junction and down to zero if necessary by the following signal, should that remain at red.

With respect, you have no way of knowing whether or not this is possible. Likewise, you take no account of differences in driving style. Again, speaking for myself, I approach red signals very cautiously. This is not because I am concerned the train won't stop on my side of the signal or anything like that, but simply to give the signaller time to clear the signal so that I don't actually have to stop.

I am certain - because it is merely factual - that braking at the flashing double yellow is a considerably more cautious practice than would occur in most other situations approaching a red.

Yes it is more cautious, but again there is nothing wrong with that. There could be any number of reasons for doing so.

The HST can - and has to - stop in the space of two signal sections in a four-aspect area and I merely wanted to know why some drivers' style at a high-speed junction was consistent with this and for some it isn't. About half the times I have observed, the train has been under power until the single flashing yellow and this has not required excessive braking or preventing the train stopping at the following signal on the occasions when it has been red.

And we have answered your questions.

The data for the braking distances is for normal braking and seems quite well researched but you could argue it's only supporting evidence. The braking distance for the HST, whatever other detail you might wish to add, has to be no more than the length of two signal sections, which round there is 2000 yds ish.

Is it...? As I pointed out before, the document you linked to gives no information about the methodology, therefore it is unwise to infer what it states. As for braking distances, it depends on what braking step you apply. An HST should be able to pull up inside 1.25 miles, but that is to ensure it can stop in an emergency. How far does it need to stop from 125mph comfortably and safely?

Either way, the braking capabilities of any class of train is not the question. You have asked a question about differences in driving styles and braking techniques that has nothing to do with braking capabilities. Unfortunately there is no definitive answer that can be given because, as has already been pointed out, each driver will do things slightly differently and have their own braking points and techniques. That is the answer based on the experience and expertise that you wished to access.

...with respect.

O L Leigh

 

[MichaelAMW]

This is replying to O L Leigh but his genuinely helpful way of interlacing his own responses makes it too complicated to try and quote.

Anyway, thanks for what you have written.

First, I really don't think my original question was patronising. I didn't say I thought one way was better than another; I asked about the differences I have observed.

In terms of drivers braking sooner than is necessary that would seem to be true, in as much as they *could* brake later. That certainly doesn't mean there's anything wrong with earlier, just that it's overall slower - as you and others have said, that may actually not matter if the timings allow for it. As you say, different drivers are comfortable wiith different driving styles.

I disagree that I can't know that the distance from the single flashing yellow to the (possible) red beyond the junction is sufficient to stop the train. That distance, in this particular case, is somewhat more than the distance from *some* double yellows on the same route to the red two signals later, which would be relevant when the train has to stop from 125 on plain line. That said, I see and appreciate what you are saying about cautious driving styles.

Maybe that document was a bit of a distraction, although I still think it is useful. The unequivocal evidence is that the signal spacing on the GW route gives 2000ish yds to stop in simple situations, i.e. plain line without this complication of flashing aspects, so that *must* be a decent braking distance, otherwise HSTs would be either "spadding" regularly or having to do soup-spilling brake applications. I'm guessing neither of those is the case.

I certainly appreciate that barrelling up to a red with an attitude that you don't need to keep a little something in reserve is a bit daft. If I have remembered correctly, the overlap in a four-aspect area only gives you 200 yds to play with, which is really not that much! Also, thinking of a conversation with a chum on this matter, approaching a red is not the same as stopping at a station - I've certainly seen heavyish, last-minute braking for that, but if you're on greens there's no safety issue, although obviously overshooting isn't exactly ideal...

Thanks again.

 

[notadriver]

Have you considered that ATP fitted on the Great Western lines may enforce a particular braking curve ? As for overshooting not being ideal and only a 200 yard overlap to play with - do you know what happens to a driver if he/she fails to call at a station or goes past a red signal within the 200 yard overlap ???????

 

[O L Leigh]

Thanks for clarifying.

I didn't suggest that your original question was patronising, but that it seemed that way to me the same way that my answers seemed patronising to you. I have been on this forum a very long time and have had many times had to defend myself and others in my grade against so-called "informed" criticism of what we do. It has made me defensive and shortened my fuse somewhat. I understand my job and take pride in it, so to have my actions questioned and critiqued by people who have little or no knowledge or experience rankles with me.

I agree that the documents you linked to have become a distracting issue to the discussion. I feel that they may not have been entirely helpful.

While I am not familiar with the route under discussion, I should point out that some of your assumptions are not necessarily correct. Signalling distances may generally be a certain amount, but it does not mean that they are always so. There are signals that are closer than expected and some that are further away. There is no such thing as a fixed distance. This may or may not be the case here, but I have no way of knowing.

There are also possible questions over whether or not the junction is always clear and the signals flashing on approach or if there are times when the route is still against the train until it gets much closer. This is not unknown at places such at Water Orton for trains taking the Leicester line. Most times the signals start to flash in good time but at others they don't flash until you're almost on top of the junction which necessitates a different braking technique. You may already have the brake on and be reducing speed because the junction signal is red when it clears. Can you be certain that at all the times you mention the yellows are actually flashing?

I'm not saying these things to stir the pot further but simply to highlight that these things are not necessarily as simple as they seem. I wouldn't wish to comment or speculate too much because I simply don't know. The driver of your train has the best view and knows what is required. And I'd like to leave this discussion at this point.

O L Leigh

 

[LE Greys]

In our experience FGW are the heaviest users for want of a better phrase of "professional" driving, it has certainly required us to inflate running times in a lot of cases.

There was an article in the RM's Practice and Performance section about a year ago about FGW's Driver Advisory System. The verdict was somewhat mixed, it was seen as distracting but fuel-saving, but it sounds like trying to follow DAS might be one reason for FGW's 'professionalism'.

 

[MichaelAMW]

Have you considered that ATP fitted on the Great Western lines may enforce a particular braking curve ? As for overshooting not being ideal and only a 200 yard overlap to play with - do you know what happens to a driver if he/she fails to call at a station or goes past a red signal within the 200 yard overlap ???????

Absolutely! I was really saying re: the overlap that, regardless of what would happen to the driver, the safety margin is only 200yds so last-minute braking for a red is clearly risky from an absolute safety point of view. Re: station stops I just meant that the safety issue, the risk of SPADing, isn't there.

V interesting to hear your mention of enforced braking curves.
--- old post above --- --- new post below ---

Thanks for clarifying.

I didn't suggest that your original question was patronising, but that it seemed that way to me the same way that my answers seemed patronising to you. I have been on this forum a very long time and have had many times had to defend myself and others in my grade against so-called "informed" criticism of what we do. It has made me defensive and shortened my fuse somewhat. I understand my job and take pride in it, so to have my actions questioned and critiqued by people who have little or no knowledge or experience rankles with me.

I agree that the documents you linked to have become a distracting issue to the discussion. I feel that they may not have been entirely helpful.

While I am not familiar with the route under discussion, I should point out that some of your assumptions are not necessarily correct. Signalling distances may generally be a certain amount, but it does not mean that they are always so. There are signals that are closer than expected and some that are further away. There is no such thing as a fixed distance. This may or may not be the case here, but I have no way of knowing.

There are also possible questions over whether or not the junction is always clear and the signals flashing on approach or if there are times when the route is still against the train until it gets much closer. This is not unknown at places such at Water Orton for trains taking the Leicester line. Most times the signals start to flash in good time but at others they don't flash until you're almost on top of the junction which necessitates a different braking technique. You may already have the brake on and be reducing speed because the junction signal is red when it clears. Can you be certain that at all the times you mention the yellows are actually flashing?

I'm not saying these things to stir the pot further but simply to highlight that these things are not necessarily as simple as they seem. I wouldn't wish to comment or speculate too much because I simply don't know. The driver of your train has the best view and knows what is required. And I'd like to leave this discussion at this point.

O L Leigh

Yes, I know that signalling distances vary, but was just saying that the minimum on the ground must still provide the full braking distance. The distance here, obtained from the NR signalling notice I linked, is (a bit) more than that here. In any case, it's the same stopping distance available to a train remaining on the DM with the signal beyond the junction at red. That must provide adequate braking distance.

Take your point about whether the route was set up at all. As it happens, I was just thinking of times when I've been having a peek out of the window and the route was set well in advance, i.e. the flashing double yellow was seen.

Thanks for your comments. Not pot stirring occurring from my POV!

 

[TDK]

whatever other detail you might wish to add, has to be no more than the length of two signal sections, which round there is 2000 yds ish.

That all depends on gradients

 

[MichaelAMW]

That all depends on gradients

Indeed, but as I said elsewhere in the same post, the relevant distance in the situation I describe is exactly the same as the available stopping distance on the parallel bit of continuous 125.

If, in fact, you were just helpfully pointing out that 2000ish yds isn't to be taken as the universal rule for stopping distance from 125 then thanks for the clarification.

 

[notadriver]

Michael my driver manager would freak if I passed a flashing double yellow at line speed never mind approaching a flashing single yellow!

 

[455driver]

At a couple of locations I drive at it is perfectly acceptable to pass the double flashing yellow at full line speed and not start braking until halfway to the single flashing yellow, there are other locations where, if you did that once, it would be tea and no biscuits.

There can never really be a hard and fast rule about these because there are so many variables.

 

[notadriver]

At a couple of locations I drive at it is perfectly acceptable to pass the double flashing yellow at full line speed and not start braking until halfway to the single flashing yellow, there are other locations where, if you did that once, it would be tea and no biscuits.

There can never really be a hard and fast rule about these because there are so many variables.

Whereabouts where you drive mate?

 

[455driver]

Whereabouts where you drive mate?

Woking on the down fast when routed into platform 5 is one where it is acceptable to let the train coast past the flashing double yellow, I have already shut off at Weybridge and just let the train run from there.

Those are very long sections.

 

[edwin_m]

It must by definition be safe to pass the flashing double yellow at line speed (or at least to start braking only when it comes into view), because if it was displaying a steady double yellow this would be the first indication of the junction signal being at red and the signalling would have to allow enough braking distance to stop there. The same applies to a flashing single yellow on a three-aspect signal.

Is this talk of passing the flashing double yellow at a reduced speed a defensive driving issue based on the driver knowing that the train is taking the diverging route before the signal comes into view? If so can somebody explain exactly what the safety benefit is? It seems to me that to bring the issue of a divergence into the driver's mind at this point may create an expectation of the normal junction signal sequence and hence increases the risk of a SPAD if the junction signal fails to release from single yellow. It is also slowing the train unnecessarily early, something the flashing aspect sequence is trying to avoid.