Is too much safety stuff dangerous?

Discussion in 'UK Railway Discussion' started by Ken H, 20 Feb 2019.

  1. Ken H

    Ken H Established Member

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    This comment prompted this thread
    So is a driver thinking he is protected by AWS likely to drive in a less defensive way than one with AWS, and therefore be actually more dangerous?

    Are we too reliant on safety backups so we dont look out for safety, but sit cocooned in a bubble not sufficiently aware for when something unexpected happens?

    They say people drive less safely because of all the safety stuff (air bags, crumple zones, side impace protection) thinking they are protected. Jeremy Clarkson said driving standards would improve if a large spike was welded to the centre of all steering wheels!

    And on the mountains, we have an excellent mountain rescue system manned by volunteers. But how many go on the hill ill equipped and have silly accidents, secure in the knowledge that 'they' will come and get them when in difficulty.

    So is safty equipment actually dangerous?

    Not knocking the safety guys, just a general discussion.
     
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  3. 12guard4

    12guard4 Member

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    AWS is flawed in my opinion. There needs to be different sound for different reasons. Its to expensive though which is why AWS is what it is.
     
  4. Mathew S

    Mathew S Established Member

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    I am not a driver, so can only comment from my limited experience of simulators, videos, etc. However, it does seem to me that AWS is a fantasically effective way of telling you that you've made a mistake, after it's too late to do anything about it. I suppose it could be effective as a mitigation against the worst consequences of such an error, but - and I'm happy to be corrected - I'm not sure how it can ever be more than that?

    Anyway, is a superior (from a safety perspective) not already available in ETCS as implemented on the Cambrian?

    On a broader point, my observation would be that all people tend to over-estimate the ability of safety systems to protect them in the event of a mishap. We act according to an - unconsciously - perceived level.of safety, rather than an objective perslceptuon of the risks. Familiar tasks especially (driving, crossing roads, etc) are perceived as less risky; and so dangerous behaviours, and lack of attentiveness, have the opportunity to creep in.
     
  5. Llama

    Llama Member

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    So long as AWS is used properly (every warning is given the attention and thought that it deserves, even in a long sequence of repetetive warnings) then it is very useful. AWS isn't meant to be any kind of in-cab signalling. I always think of it as it is intended - once I acknowledge an AWS warning then I am accepting responsibility for controlling the train as required and if I didn't acknowledge a warning then the automatic brake application would do it for me. Once you have driven without AWS you appreciate exactly how much its use is ingrained into your normal driving.
     
  6. Bletchleyite

    Bletchleyite Veteran Member

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    Hasn't TPWS basically replaced it in any meaningful sense, though?
     
  7. DarloRich

    DarloRich Veteran Member

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    Answer: No
     
  8. Bletchleyite

    Bletchleyite Veteran Member

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    Repeated safety warnings can be, as they cause people to tune them out due to overload, though.
     
  9. Llama

    Llama Member

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    That is a human factors issue down to the individual though, drivers should be aware of the risk of repeated warnings (eg AWS) and recognise the risk of failing to process one of them when that situation is playing out in front of them.
     
  10. DarloRich

    DarloRich Veteran Member

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    i take the point ( however the AWS is a vigilance system designed to be annoying) but i would rather railways were over safe. However as always this board only looks at drivers and gaurds. The railway is much wider than that.
     
  11. Bletchleyite

    Bletchleyite Veteran Member

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    Though the human factor there shows just how poor an automaton a human actually is. Even if you don't go for ATO, a form of cab signalling that gives a more continuous flow of information more suited to the human brain is a lot safer.
     
  12. Llama

    Llama Member

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    Would a more continuous flow of information not be just as dangerous though in becoming 'noise' that a person becomes desensitised to? So long as drivers know when to heighten their awareness and relax it (at the right times!) then an argument could be made that a system that reflects that and requires no attention when none is necessary and barks at you when you need to process some information is more appropriate for the job in hand?
     
  13. big all

    big all On Moderation

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    because green signals tend not to register
    the best use off aws is when you need reassurance the last signal was a green:D
     
  14. rf_ioliver

    rf_ioliver Member

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    Complex answer, but basically "no" if implemented and used correctly. So what does that mean? Well, you have to delve into the fascinating world of safety-critical systems. There is a HUGE amount of knowledge and research into human behaviour, automation etc covering these aspects.

    To get a good understanding I recommend reading anything by James Reason: https://www.goodreads.com/author/list/637048.James_Reason

    The book "A life in Error" is the easiest to read and in it he gives a series of anecdotes, stories etc about his work, accidents, safety culture etc.

    t.

    Ian
     
  15. HaggisBotherer

    HaggisBotherer On Moderation

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    This thread in a nutshell:

    Is safety equipment actually dangerous? No
    Is human error dangerous? Yes.
     
  16. Dieseldriver

    Dieseldriver Member

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    I'm curious as to why you think that AWS is only useful for telling you you've made a mistake? It provides a prior warning of lower speeds/restrictive signals which, if a Driver fails to cancel, AWS will apply the brakes. I could be unconscious approaching a single yellow and AWS will apply the emergency brake to stop me before the red. That's completely preventing an incident.
     
  17. DanDaDriver

    DanDaDriver Member

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    Only as a way of stopping a train spadding that can’t easily be over-ridden. TPWS can’t remind you of a speed restriction or let you know which way a Junction is set in the dark.
     
  18. Llama

    Llama Member

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    This is a good example of the difference between a simulator and being out in the cab. In a simulator you drive a 'train', in the cab you drive the route.
     
  19. SHD

    SHD Member

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    Are you sure, taking into account the application delay, that AWS application of emergency brake will ensure a safe stopping/speed reduction before the train enters the danger zone?

    As far as I understand, AWS is the equivalent of a crocodile system and does not provide protection against approaching danger at undue speeds. AWS does not stop a driver from reaccelerating (voluntarily or not) after passing a signal at caution, am I right?
     
  20. Dieseldriver

    Dieseldriver Member

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    I don't think you fully understand AWS, yes the train would be stopped before the red, brought down to a safe speed before the lower restriction. The only time this might not be the case is if there is exceptionally poor railhead conditions.
     
  21. Taunton

    Taunton Established Member

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    This was the Southern Region "Signal Repeating AWS" (SRAWS) which they devised in the 1970s and was fitted on the eastbound Bournemouth-Southampton line, and to the east end cabs of the 4-REP units, as an extended trial. It showed the last aspect in the cab, which had to be acknowledged individually, with different tones. Wasn't expensive, compatible with existing AWS fittings, and was cleverly thought out. Cancelled by political infighting and a "not invented here" attitude from BRB headquarters.
     
  22. SHD

    SHD Member

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    Well I am eager for enlightenment on AWS...:o
    Does it ensure that the train stops before the signal at danger if the caution signal is passed at a speed that, while under or equal to the maximal permissible speed for the route, is too high for the train category? Does it prevent re-acceleration after passing a signal at caution, without ensuring that the next signal does not present "danger" anymore?
     
  23. sw1ller

    sw1ller Established Member

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    Ttttt
    I think you’re forgetting the AWS on the distant signal too. You’re right if @Dieseldriver fell unconscious right after the distant and had not yet started to apply the brake. In this scenario, you’d approach the red way too fast for the AWS to have any effect. However, if there was a significant “danger zone” then there would be TPWS and/or TPWS+ fitted. This won’t stop you going through a red, but it’s designed to stop you before you enter any conflicting area.
     
  24. pdeaves

    pdeaves Established Member

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    In the general case (i.e. not specifically to do with train driving) I agree that providing too much safety protection can have the potential to be counter productive. People get used to 'something' being in place to protect them from the hazard so much that if the 'something' fails/isn't in place they put themselves in peril. For a similar mentality, look at all the people who drive vehicles into silly places because the sat-nav said so (or didn't say otherwise): common sense overridden by the machine.
    I have seen CCTV evidence recently of someone removing a safety guard and carrying on because, in this case, the guard could be moved. No thought as to why it was there or what effect it could have on others later on (there is more to the story, but this illustrates my point).
    The potential bad consequences get hidden so people do not see the importance of the safety protection.
     
  25. robbeech

    robbeech Established Member

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    I think this is one point many non train drivers (I am a non train driver) might gloss over.
    AWS has 2 forms of warning. One is the horn which must be acknowledged and the other the sunflower or lack thereof which reminds the driver that the last magnet was something that may have required an action such as slowing down. Of course this is not perfect, a Morpeth board with an AWS magnet for an upcoming speed restriction may be followed closely by a signal with a proceed aspect.
     
  26. MarkyT

    MarkyT Established Member

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    Correct. If a driver acknowledges the distant warning within a few seconds, there is no further control over speed. If there is no acknowledgement, a full service braking application is initiated, which cannot be overridden until the train has come to a stand. Originally, I believe French 'Crocodile' was an audible warning only at or on approach to the distant by means of a solenoid controlled valve sounding the steam whistle. That was a very early system dating back to the late 1800s based on electrical contact and was not failsafe, so if the trackside battery failed there would be no warning. The slightly later GWR ATC system in UK was better in this respect, with the ramp providing a positive mechanical actuation regardless of power supply status. Only if the ramp contact strip was successfully energised would a clear indication be given, otherwise a warning would sound and an automatic brake application be initiated, unless acknowledged, just like the later BR magnetic system.
     
  27. Dieseldriver

    Dieseldriver Member

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    All this discussion about whether AWS is a good system or not or whether it has improved safety or not seems very strange to me anyway. I'm assuming that everyone has heard of the multitude of major railway disasters in the last century on lines not fitted with AWS which influences the roll out of this simple yet effective system? If AWS was eradicated overnight, I'm sure we'd enjoy discussing the modern day 'Southalls' and 'Harrows' and 'Eccles' on this forum.
     
  28. Dieseldriver

    Dieseldriver Member

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    I'm not arguing that AWS doesn't have its limitations, it does. However, the vast majority of the time, once a Driver has cancelled an AWS warning, they will take steps to react to it by shutting off and applying the brake. It is extremely rare for this not to be the case. Together with TPWS, AWS has ensured that in October of this year, we will have suffered zero fatalities in the UK due to a SPAD for twenty years. This is an incredible achievement brought about by a combination of widespread AWS, the national rollout of TPWS and the improved understanding of human factors and non technical skills. AWS on its own is still massively better than no system at all but in the vast majority of cases it is supplemented with TPWS which had contributed to our enviable safety record over the last couple of decades.
     
  29. MarkyT

    MarkyT Established Member

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    Indeed, which is why it and similar systems were the earliest driver assist systems to be rolled out widely on main line railways the world over, along with mechanical trainstops on urban metros. The Crocodile system in France was first developed in the 1870s, the GWR ATC in early 1900s and fully rolled out on main lines by the 1930s. 'Waking the driver up' at the last point he could possibly start braking to stop at the first home is the most important intervention. USA had a magnetic based ATC with similar functionality widely from the 1920s, which was largely removed starting in the 1950s as passenger services were withdrawn. Germany had inductive PZB from the 1930s which incorporates a more sophisticated distant warning function that applies an ongoing speed reduction and restriction requirement for a set distance beyond the transponder. Belgium and Luxembourg used the Crocodile. There is then a whole series of systems using track circuit codes to implement speed controls. These effectively implement a distant warning by means of the first transition from an unlimited code to a limited code. Examples are in use in USA, Netherlands, Republic of Ireland, China, Japan etc. Older high speed control systems such a French TVM also use coded track circuits. On modern railways warning and protection systems are absolutely essential to ensure adequate safety.
     
  30. alxndr

    alxndr Member

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    This sounds rather like the old thoughts on signallers' reminder appliances - it would stop them needing to think and make them sloppy. I don't think any of us would want to go out without knowing the signaller had collared up these days.
     
  31. Mathew S

    Mathew S Established Member

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    My understanding (which I'm more than happy to have corrected) is that if a train is running at linespeed (e.g. 125mph), AWS is triggered by a restrictive signal, and the driver fails to cancel it, there is not always going to be sufficient time/distance for the train to be brought to a halt by the automatic systems before it passes the signal. That's what was behind my point about it potentially being a mitigation for passing a signal which should not have been passed, as opposed to a way of preventing that happening in the first place.

    EDIT: The discussion above has been very informative. My concern (for want of a better word, it doesn't actually concern me at all because it's so rare) about AWS is that there are still edge cases where a train can pass a signal at danger, due to human error. The question isn't (shouldn't be) whether AWS is completely ideal, but whether it's the best way of managing the risk.
     

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