RMweb Gold martin_wynne Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 An alarming incident at Walkergate station that day. If you were on the train, RAIB would like to hear from you: http://www.raib.gov.uk/publications/current_investigations_register/140811_walkergate.cfm Link to post Share on other sites More sharing options...
Bomag Posted August 29, 2014 Share Posted August 29, 2014 '30 passengers on the train who self-evacuated on to the platform' Does the author know what this actually means? But the again I am not surprised some of that were bricking it! Link to post Share on other sites More sharing options...
Edwin_m Posted August 29, 2014 Share Posted August 29, 2014 Seems to be the standard terminology for those who leave a train in emergency without authorisation. Better get used to it. This seems worryingly similar to another incident on Metro: https://aib-cms.co.uk/sites/raib/latest_news/news_archive/news_archive_2013/130925_pn_south_gosforth.cfm Link to post Share on other sites More sharing options...
kenw Posted August 29, 2014 Share Posted August 29, 2014 '30 passengers on the train who self-evacuated on to the platform' Does the author know what this actually means? But the again I am not surprised some of that were bricking it! To quote fully; "However, there were at least 30 passengers on the train who self-evacuated on to the platform using the train doors' emergency release handles" So they used the emergency release (which all power train doors have) to open the doors without them being released by the driver. The danger here is this may have been done before the overhead power was isolated. Link to post Share on other sites More sharing options...
CUTLER2579 Posted August 29, 2014 Share Posted August 29, 2014 A bit of a dilemma here for Joe Public ,do you burn or do you get electrocuted. Hard to criticise people who open the emergency doors in such a situation especially not knowing that the overhead line is going to break and come crashing down. Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 What I find worrying about this incident is the length of time for which the overhead apparently remained live, 14 seconds seems a heck of a time for a relatively low voltage system to earth out and trip the circuit breakers. Link to post Share on other sites More sharing options...
kenw Posted August 29, 2014 Share Posted August 29, 2014 A bit of a dilemma here for Joe Public ,do you burn or do you get electrocuted. Hard to criticise people who open the emergency doors in such a situation especially not knowing that the overhead line is going to break and come crashing down. Yes, but that's what happened, which is what the question I was replying to asked. Link to post Share on other sites More sharing options...
Fat Controller Posted August 29, 2014 Share Posted August 29, 2014 I'm curious to know if the fire and the subsequent catenary failure were linked, or simply coincident..Perhaps some sort of over-voltage, first causing overheating in on-train components, then failure of the OCS itself? Regarding the incident itself, I know from personal experience that it's hard enough to get passengers to go or stay where you want them to when you're face-to-face with them; asking them to act counter-intuitively remotely must be very difficult. SNCF almost had a major incident a while back near Villeneuve-St-Georges in similar circumstances; in that case, the train had failed short of the platform, so the passengers de-trained on to the ballast. The problem was that they did so on both sides of the train, and the adjacent track had not yet been closed to traffic...Again, the train was driver-only, and the doors were forced open before the driver had a chance to do anything. Link to post Share on other sites More sharing options...
Southernman46 Posted August 29, 2014 Share Posted August 29, 2014 Potentially the breakers could remain closed if the fault was of high resistance - i.e. no good earth /negative path (it just replicates a heavy system load) - rusty metal contacting a rusty conductor rail has the same effect, or hadn't triggered any rate of current rise protection or caused any loss of traction continuity between substations. It sounds as though loss of continuity caused the tripping eventually. ISTR for example that, Southern Region DC HSCB's are usually set to trip at loads of around 7000+ amps, can't remember the rate of rise characteristic but it's something like 1500 amps / Sec ??. This does occasionally result in tripping under normal load if say 2 - 3 trains are drawing power at the same time - not uncommon in areas like London Bridge & Clapham Jn. I have witnessed conductor rail insulator flashovers in the rain where the arcing (fault) has lasted for upwards of 10 - 25 seconds before stopping - usually because the insulator has exploded rather than a circuit-breaker tripping. Have also seen a 750v power jumper on a 4-EPB fault in the same way and continue until the breakers were opened by the ECRO Unfortunately the GP would not understand that remaining inside the train is their best protection in such an incident (except of course if a train fire resulted). Others will know more - being in mind I changed from Electrification to being a PW Engineer in 1996 EDIT: Just read the RAIB précis some of the above post is irrelevant. The re-energisation will have been done by the ECRO - standing instructions when a CB trip occurs, on the SR two further re-closes are permitted in a set time period before the CB is left open (unless the ECRO is requested to open the CB's in the intervening time). This is because the vast majority of trippings are traction load related. Link to post Share on other sites More sharing options...
RMweb Premium jamie92208 Posted August 29, 2014 RMweb Premium Share Posted August 29, 2014 I happenned to read the RAIB report into the earlier incident that is referenced in the posting. ISTR that it brought our some serious potential faults in the Circuit Breakers and made several reccommendations about how such incidents should be managed. It will be very interesting to see how that process in being progressed. I'm glad that no one was injured. Jamie Link to post Share on other sites More sharing options...
RMweb Gold Colin_McLeod Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 It is natural to want to get out in the event of a fire or similar emergency. Buildings are designed to enable such action. Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 I happenned to read the RAIB report into the earlier incident that is referenced in the posting. ISTR that it brought our some serious potential faults in the Circuit Breakers and made several reccommendations about how such incidents should be managed. It will be very interesting to see how that process in being progressed. I'm glad that no one was injured. Jamie I understand from my local contact that the recent incident was on newer train of a type which post dates the previous incident and, according to him, should have received any modification arising out of the earlier incident. It is also his understanding that changes to Instructions following the earlier incident might not have been very helpful in this one. Incidentally I also understand from that the 14 second figure quoted might not be correct and could be an over-estimate. Link to post Share on other sites More sharing options...
RMweb Gold Colin_McLeod Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 This is indeed a serious and potentially lethal incident. If you are a witness and haven't contacted authorities about it yet, please do get in touch. I'm sure your local police station would be happy to take your statement and send it along if you're hesitant contacting RAIB directly. The life you saved might be your own! (or worse: someone you love!) Hi, Id be interested to know how the passengers can add anything further that would save lives. Link to post Share on other sites More sharing options...
stewartingram Posted August 29, 2014 Share Posted August 29, 2014 I believe it is normal for electrical controllers to rest trips 3 times if they go. If then they won't reset, they send someone to investigate the reason for tripping. Stewart Link to post Share on other sites More sharing options...
CUTLER2579 Posted August 29, 2014 Share Posted August 29, 2014 Yes, but that's what happened, which is what the question I was replying to asked. I appreciate that, what I am saying is if I was in there and it was on fire, as an ex-railwayman (Electrical Fitter) I would have gone for evacuating and taking a chance on getting electrocuted, rather than getting smoke inhalation and possible serious burns as opposed to the lesser risk of the shock treatment as I would have expected the overloads to have tripped and nullified the danger of Frying Tonight. Link to post Share on other sites More sharing options...
Edwin_m Posted August 29, 2014 Share Posted August 29, 2014 I understand from my local contact that the recent incident was on newer train of a type which post dates the previous incident and, according to him, should have received any modification arising out of the earlier incident. It is also his understanding that changes to Instructions following the earlier incident might not have been very helpful in this one. Incidentally I also understand from that the 14 second figure quoted might not be correct and could be an over-estimate. Metro hasn't had any new trains since it was built. Your contact may have been referring to a refurbishment programme which all trains have been going through and involves a major strip-down and rebuild. Difficulty in detecting faults is intrinsic to low-voltage electrification systems, the more so the lower the voltage. This is because to deliver the necessary power requires a high current and as Southernman notes the current in a short circuit situation will be not that much more than several trains taking power at once. There is also the risk that a short circuit with significant resistance remaining, such as if the wires fall but don't touch the train or rails, will not be detected immediately either (but the suggestion that the wire stayed live after touching the train suggests this doesn't apply here). This is the same sort of reason that DCC users are urged to do a coin test to test the effectiveness of their auto-cutouts! High voltage AC systems are much safer in this respect at least, because the trains draw less current for the same power, and with the voltage being higher the fault current through the same resistance is much greater too. So the difference between the two is immediately detectable. Link to post Share on other sites More sharing options...
Fat Controller Posted August 29, 2014 Share Posted August 29, 2014 I appreciate that, what I am saying is if I was in there and it was on fire, as an ex-railwayman (Electrical Fitter) I would have gone for evacuating and taking a chance on getting electrocuted, rather than getting smoke inhalation and possible serious burns as opposed to the lesser risk of the shock treatment as I would have expected the overloads to have tripped and nullified the danger of Frying Tonight. I wouldn't be prepared to go near that catenary until it was confirmed both dead and earthed; there was an incident involving a Eurostar at St Pancras a while back, where the contact wire broke and flailed across the platform. It remained live throughout.. http://www.raib.gov.uk/cms_resources.cfm?file=/100805_R122010_StPancras.pdf Link to post Share on other sites More sharing options...
RMweb Gold SHMD Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 A bit of a dilemma here for Joe Public ,do you burn or do you get electrocuted. Hard to criticise people who open the emergency doors in such a situation especially not knowing that the overhead line is going to break and come crashing down. ..out of the fire and into the frying pan.. Link to post Share on other sites More sharing options...
trisonic Posted August 29, 2014 Share Posted August 29, 2014 Some overhead lines do not trip when broken, Downed power lines are an issue over here because outside of towns most delivery is via OHL. Too many people are killed via wet streets, Armco (see movie “Ice Storm”) or just exiting their vehicles. you don’t have to contact the live cable. This is quite a good safety film (and quite entertaining without being at all grisly): Best, Pete. Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted August 29, 2014 RMweb Gold Share Posted August 29, 2014 Metro hasn't had any new trains since it was built. Your contact may have been referring to a refurbishment programme which all trains have been going through and involves a major strip-down and rebuild. Difficulty in detecting faults is intrinsic to low-voltage electrification systems, the more so the lower the voltage. This is because to deliver the necessary power requires a high current and as Southernman notes the current in a short circuit situation will be not that much more than several trains taking power at once. There is also the risk that a short circuit with significant resistance remaining, such as if the wires fall but don't touch the train or rails, will not be detected immediately either (but the suggestion that the wire stayed live after touching the train suggests this doesn't apply here). This is the same sort of reason that DCC users are urged to do a coin test to test the effectiveness of their auto-cutouts! High voltage AC systems are much safer in this respect at least, because the trains draw less current for the same power, and with the voltage being higher the fault current through the same resistance is much greater too. So the difference between the two is immediately detectable. Yes Edwin it was a refurbished train - they seem to like referring to them as 'new' locally because of the livery. Link to post Share on other sites More sharing options...
Grovenor Posted August 29, 2014 Share Posted August 29, 2014 there was an incident involving a Eurostar at St Pancras a while back, where the contact wire broke and flailed across the platform. It remained live throughout.. If you read the report the wire did NOT remain live, it tripped at the time of break and tripped again each time re-energisation was attempted. Keith Link to post Share on other sites More sharing options...
Fat Controller Posted August 29, 2014 Share Posted August 29, 2014 If you read the report the wire did NOT remain live, it tripped at the time of break and tripped again each time re-energisation was attempted. Keith In that case, it would have been live each time it was re-energised; in either case it was potentially lethal. Link to post Share on other sites More sharing options...
Edwin_m Posted August 29, 2014 Share Posted August 29, 2014 It was live for a fraction of a second each time before it cut out again, so anyone touching it when that happened would have been in trouble but hopefully people have more sense than that. During its initial descent, when people might have been underneath, it appears to have struck the roof of the train so probably cut out before it dropped onto the platform. Link to post Share on other sites More sharing options...
Southernman46 Posted August 30, 2014 Share Posted August 30, 2014 Also, the residual charge in a "dead" section of overhead cable will render it as lethal at needs to be.................... Link to post Share on other sites More sharing options...
Edwin_m Posted August 30, 2014 Share Posted August 30, 2014 Even if it's earthed itself by contact with something else? Link to post Share on other sites More sharing options...
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