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Why can't LU cope with a signal failure?
Here we go again, the whole clockwise section of the Circle &
H&C line was buggered up because of a single signal failure. Just how hard is it to cope with a light stuck on red? Train gets to signal , line controller gives clear if ok to move , train moves across signal, resets , continues on journey. This isn't bloody rocket science so can someone explain why LU goes to hell in a handbasket as soon as something like this happens?? Its not like it hasn't been happening for the last 120 years which to me seems like a reasonable amount of time to sort out a practical solution which doesn't involve trains going nowhere for 15 bloody minutes. FFS , just how complex a procedure is it? B2003 |
Why can't LU cope with a signal failure?
Boltar wrote:
Here we go again, the whole clockwise section of the Circle & H&C line was buggered up because of a single signal failure. Just how hard is it to cope with a light stuck on red? Train gets to signal , line controller gives clear if ok to move , train moves across signal, resets , continues on journey. This isn't bloody rocket science so can someone explain why LU goes to hell in a handbasket as soon as something like this happens?? Its not like it hasn't been happening for the last 120 years which to me seems like a reasonable amount of time to sort out a practical solution which doesn't involve trains going nowhere for 15 bloody minutes. FFS , just how complex a procedure is it? If the signal is on red because the track circuit shows the section of track beyond it as occupied (which I believe is the a common reason for a signal "stuck on red"), how would the line controller miles away from the fault know that it's "OK to move"? -- Richard J. (to e-mail me, swap uk and yon in address) |
Why can't LU cope with a signal failure?
a signal "stuck on red"), how would the line controller miles away from
the fault know that it's "OK to move"? Well , just a shot in the dark here , but maybe they could keep tabs on where the trains are? I mean that is their job, right? Unless the train radio is for listening to Terry Wogan. B2003 |
Why can't LU cope with a signal failure?
In effect you are right, the signaller will know when a train has left
the affected section and be able to authorise a train to pass the affected signal BUT not over the train radio, BUT when passing a signal failure red the train will then be stuck doing "a speed at which you can stop short of any obstruction" in other words the train will be doing under 10 mph (if you try to exceed 10mph the brakes will come on), 5mph or less is more likely (There's an alert noise if you go over 7mph, doing 5mph keeps the cab noise down!) this is for 2 correctly working signals, if the next one is also failing (not uncommon) then the whole process has to be started again. That is why 1 signal failure can FUBAR the whole Met, Hot & Cold, & Circle line. Boltar wrote: Here we go again, the whole clockwise section of the Circle & H&C line was buggered up because of a single signal failure. Just how hard is it to cope with a light stuck on red? Train gets to signal , line controller gives clear if ok to move , train moves across signal, resets , continues on journey. This isn't bloody rocket science so can someone explain why LU goes to hell in a handbasket as soon as something like this happens?? Its not like it hasn't been happening for the last 120 years which to me seems like a reasonable amount of time to sort out a practical solution which doesn't involve trains going nowhere for 15 bloody minutes. FFS , just how complex a procedure is it? B2003 |
Why can't LU cope with a signal failure?
That it what I thought, air traffic controllers can manage it. They can
put a satalite on the moon of Jupiter without actually having to be there to see it. Kevin |
Why can't LU cope with a signal failure?
In article .com,
Boltar writes Just how hard is it to cope with a light stuck on red? Firstly you need to determine why the signal is red - stuck train, broken track, or failure of the signal system. Secondly, if the signal protects something like points, you need to get them secured before allowing trains to run over them. Thirdly, the service is intensive enough that the delays in "tripping by" can completely screw up timings, leaving trains and train crews in the wrong place. Fourthly, if the problem is trackside then someone needs to go and fix it before the service will get back to normal. This requires stopping trains while they're working on the particular bits of equipment. -- Clive D.W. Feather | Home: Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org Fax: +44 870 051 9937 | Work: Please reply to the Reply-To address, which is: |
Why can't LU cope with a signal failure?
wrote ...
They can put a satalite on the moon of Jupiter Wrong . . . It was Saturn, not Jupiter. A satellite is in orbit round something, not landed upon it. |
Why can't LU cope with a signal failure?
|
Why can't LU cope with a signal failure?
In effect you are right, the signaller will know when a train has left
the affected section and be able to authorise a train to pass the affected signal BUT not over the train radio, BUT when passing a signal failure red the train will then be stuck doing "a speed at which you can stop short of any obstruction" in other words the train will be doing under 10 mph (if you try to exceed 10mph the brakes will come on), 5mph or less is more likely (There's an alert noise if you go over 7mph, doing 5mph keeps the cab noise down!) this is for 2 correctly working signals, if the next one is also failing (not uncommon) then the whole process has to be started again. Sounds like the system needs to revised then, or perhaps put some backup sensors in the system or perhaps the block the signal controlled be taken over by another signal so you have a double sized block allowing trains to pass and allowing the duff signal to be taken out of service and repaired. Its not beyond the wit of man to come up with a solution that doesn't involve incoveniencing thousands of people when you've had over a century to think one up. B2003 |
Why can't LU cope with a signal failure?
"Boltar" wrote ...
Its not beyond the wit of man to come up with a solution that doesn't involve incoveniencing thousands of people when you've had over a century to think one up. The problem surely is not the whole of the last 100 years, but the last 5-10 when the press have become so obsessed with certain aspects of public safety and the appearance of the compensation culture that these very stringent measures have had to be adopted. Blame the press, not LU. |
Why can't LU cope with a signal failure?
Wonga, Dosh, spondoliks, PPP, these are the reasons why it will take
years to change the signalling system, ATO has been mentioned but again don't hold your breath. Boltar wrote: In effect you are right, the signaller will know when a train has left the affected section and be able to authorise a train to pass the affected signal BUT not over the train radio, BUT when passing a signal failure red the train will then be stuck doing "a speed at which you can stop short of any obstruction" in other words the train will be doing under 10 mph (if you try to exceed 10mph the brakes will come on), 5mph or less is more likely (There's an alert noise if you go over 7mph, doing 5mph keeps the cab noise down!) this is for 2 correctly working signals, if the next one is also failing (not uncommon) then the whole process has to be started again. Sounds like the system needs to revised then, or perhaps put some backup sensors in the system or perhaps the block the signal controlled be taken over by another signal so you have a double sized block allowing trains to pass and allowing the duff signal to be taken out of service and repaired. Its not beyond the wit of man to come up with a solution that doesn't involve incoveniencing thousands of people when you've had over a century to think one up. B2003 |
Why can't LU cope with a signal failure?
Its the fault of the press and compensation culture for the inability
of LUL to deal with a signal fault, utter ********. Kevin |
Why can't LU cope with a signal failure?
? am I the only one confused by this post!
wrote: Its the fault of the press and compensation culture for the inability of LUL to deal with a signal fault, utter ********. Kevin |
Why can't LU cope with a signal failure?
In article ,
Tom Anderson wrote: I think a whizzy high-tech moving block system can avoid these problems, though; the system would (or should) have a battery of redundant sensors and communications links, so it can keep accurate tabs on every train at all times. Until they fail or give contradictory results, in which case you have ... a red signal (or in-cab equivalent) that trains must not cross ! Just like boltar2003[*] is whinging about. Nick[*] isn't he a couple of years behind the times now ? -- http://www.leverton.org/ ... So express yourself |
Why can't LU cope with a signal failure?
"Vernon" wrote in message ... "Boltar" wrote ... Its not beyond the wit of man to come up with a solution that doesn't involve incoveniencing thousands of people when you've had over a century to think one up. The problem surely is not the whole of the last 100 years, but the last 5-10 when the press have become so obsessed with certain aspects of public safety and the appearance of the compensation culture that these very stringent measures have had to be adopted. Blame the press, not LU. The Underground have long had backup safety procedures such as this in place to work trains through sections safely in the event of signal failures. The procedure described (trains travelling at very low speed until having passed two known working signals) has been in place at least since the 1970s and indeed possibly far earlier, nothing to do with the press becoming obsessed with public safety in recent years. Andrew |
Why can't LU cope with a signal failure?
Having read all the replies to this thread, my feeling is that as soon
as LUL start dealing with a "light stuck on red" then the more worried I will be about safety. The term "signal failure" is a bit of a misnomer - it indicates to the general public that the signal mechanism isn't working, when, according to TfL, it means that the signal has failed to go back to green. The current system strikes me as fairly robust, and I think it would be difficult to solve it all at once. |
Why can't LU cope with a signal failure?
On 26 May 2005 05:16:14 -0700, wrote:
That it what I thought, air traffic controllers can manage it. They can put a satalite on the moon of Jupiter without actually having to be there to see it. I don't think air traffic controllers have ever done anything remotely resembling that. -- http://gallery120232.fotopic.net/ps10754877.html (British Steam Locomotives (main line)) |
Why can't LU cope with a signal failure?
On 26 May 2005 15:36:17 -0700, ONscotland wrote:
The term "signal failure" is a bit of a misnomer - it indicates to the general public that the signal mechanism isn't working, when, according to TfL, it means that the signal has failed to go back to green. Exactly. The signal hasn't failed, because its primary purpose is to prevent a collision. It has succeeded. Given the choice between being dead or slightly delayed, I feel most commuters would elect delayed. However, an efficient railway need not be unduly delayed by such a failure. If only the signalling mechanism has failed, then it's going to be cost-effective to dedicate a couple of staff to operating the system the old fashioned way until the problem can be rectified. It's the lack of mamnagement imagination needed to see that which irritates people. -- http://gallery120232.fotopic.net/p9680076.html (73 126 on a mixed freight working at Worthing in 1985) |
Why can't LU cope with a signal failure?
In message , General Von
Clinkerhoffen writes In effect you are right, the signaller will know when a train has left the affected section and be able to authorise a train to pass the affected signal BUT not over the train radio, BUT when passing a signal failure red the train will then be stuck doing "a speed at which you can stop short of any obstruction" in other words the train will be doing under 10 mph (if you try to exceed 10mph the brakes will come on), 5mph or less is more likely (There's an alert noise if you go over 7mph, doing 5mph keeps the cab noise down!) this is for 2 correctly working signals, if the next one is also failing (not uncommon) then the whole process has to be started again. 73 stock doesn't have the sounder at 7mph, but you will still come up in a heap if you try and go faster than 10mph in slow speed. Also, the next bit of the rule that you didn't quote also shows how things get held up: "past the next two stop signals showing a clear or caution aspect.". Last time I had to apply the rule at a failing signal it took me 10 minutes just to get through the affected section and a total of 15 mins from stopping at the failing signal to resuming normal line speed. This with a 2-3 minute interval service, you can see why the job is fubar in very short order. That is why 1 signal failure can FUBAR the whole Met, Hot & Cold, & Circle line. And that's just for an automatic signal - it gets worse if there's points involved as they have to be secured too. -- Steve Fitzgerald has now left the building. You will find him in London's Docklands, E16, UK (please use the reply to address for email) |
Why can't LU cope with a signal failure?
Just like boltar2003[*] is whinging about
You'd whinge too if you were stuck in a hot carriage for 20 mins with a hundred other sweaty victims. [*] isn't he a couple of years behind the times now ? Not as far behind as LU. :) B2003 |
Why can't LU cope with a signal failure?
The Underground have long had backup safety procedures such as this in place
to work trains through sections safely in the event of signal failures. The procedure described (trains travelling at very low speed until having passed two known working signals) has been in place at least since the 1970s and Well that certainly explains the delays. Is there any particular reason for keeping this absurd pantomime or is it just a case of the thats-how-its-always-been-done mentality? B2003 |
Why can't LU cope with a signal failure?
Boltar wrote:
The Underground have long had backup safety procedures such as this in place to work trains through sections safely in the event of signal failures. The procedure described (trains travelling at very low speed until having passed two known working signals) has been in place at least since the 1970s and Well that certainly explains the delays. Is there any particular reason for keeping this absurd pantomime or is it just a case of the thats-how-its-always-been-done mentality? Undoubtedly, with the application of different technology, there are different ways of doing it, one such scheme was being developed for the Jubilee Line extension. However, apart from the JLE, central Government has starved LU of investement funds since 1984. |
Why can't LU cope with a signal failure?
In article , Chris Tolley
writes However, an efficient railway need not be unduly delayed by such a failure. If only the signalling mechanism has failed, then it's going to be cost-effective to dedicate a couple of staff to operating the system the old fashioned way until the problem can be rectified. What do you mean by "the old fashioned way" in this case? -- Clive D.W. Feather | Home: Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org Fax: +44 870 051 9937 | Work: Please reply to the Reply-To address, which is: |
Why can't LU cope with a signal failure?
In article .com,
Boltar writes The Underground have long had backup safety procedures such as this in place to work trains through sections safely in the event of signal failures. The procedure described (trains travelling at very low speed until having passed two known working signals) has been in place at least since the 1970s and Well that certainly explains the delays. Is there any particular reason for keeping this absurd pantomime or is it just a case of the thats-how-its-always-been-done mentality? Well, I suspect that the friends and relatives of those killed in the various collisions [+] after trains tripped past signals[*] would have preferred that it had been done this way for longer. [*] For some reason a number of these were on the Central Line between Leyton and Stratford. [+] For example, on 1953-04-08 twelve passengers were killed in a collision just in rear of signal A491, which had failed. The driver of the rear train failed to control his speed after tripping past A489. -- Clive D.W. Feather | Home: Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org Fax: +44 870 051 9937 | Work: Please reply to the Reply-To address, which is: |
Why can't LU cope with a signal failure?
If the failure occurs in a 'controlled area', it's likely points will
need securing by hand ('remote securing' is generally confined to the tube lines). Response times are not helped by: Stations that are unstaffed. Stations with staff that are medically-restricted from going on the track. Stations with staff that are quite competant but whose authorising licence is out of date. Stations with staff that simply claim they don't feel competant to carry out the task (this is apparently acceptable under the Health n-Safety culture/scam of today). Stations with staff that want traction current turned off first, extending the delay and plunging trains into near darkness (this is mandatory in a few restricted areas, but not at all locations). Stations with staff unfamiliar with the area - i.e. unable to find points concerned or who secure the wrong set, or in the wrong direction. Apart from that, it's all plain-sailing! |
Why can't LU cope with a signal failure?
wrote in message oups.com... If the failure occurs in a 'controlled area', it's likely points will need securing by hand ('remote securing' is generally confined to the tube lines). Is it??? Response times are not helped by: Stations that are unstaffed. Never come across that one as a reason for a delay regarding signal failure. You must remember that not all signals are located next to stations. If securing points is required a long walk can be needed.....it takes time. Stations with staff that are medically-restricted from going on the track. Cant leave a station with no one competent to go on the track.....never had this as a reason, like above. Stations with staff that are quite competant but whose authorising licence is out of date. Same as above, If the licence is out of date they cant be in safety critical areas. It does happen for various reasons, mainly being sick when Annual Test Of Rules, (ATOR) is due. Its your responsibility to keep licence up to date and if not done you could be stood down...no pay. Its never happened in my experience that this has been a reason for an extended delay. Stations with staff that simply claim they don't feel competant to carry out the task (this is apparently acceptable under the Health n-Safety culture/scam of today). If anyone said that to me i'd want to know why they signed in stating they were fit for duty. Sure, as in all workforces people do get sick on duty and Murphy said its bound to happen as soon as this happens. You aren't competent??? Re-training and or redeployment. BUT, would you want to go down next to 630v with someone who says "i'm not sure about what i'm doing" Stations with staff that want traction current turned off first, extending the delay and plunging trains into near darkness (this is mandatory in a few restricted areas, but not at all locations). Turning off traction current takes seconds as does restoring it. Will not extend a delay by more than a minute. Trains do not go into "near darkness" as they all have battery lights in each car AND tunnel lighting comes on automatically. If someone wants power off....thats fine with me, its the actions after that count. You cant frighten people into working in an area they consider dangerous to themselves. Stations with staff unfamiliar with the area - i.e. unable to find points concerned or who secure the wrong set, or in the wrong direction. Station staff must be familiarised with the area they work every 6 months. The people involved in going on the track would be Supervisor or Duty Manager. These people know the area more than say barrier staff would (but not always - but generally these are newer staff members)- Finding a set of points is actually pretty simple - just follow the 2 silver things on the floor. Before going on the track a briefing is held to ensure all concerned know where they go, which points and which way. (Could save time with no briefing but false economy and dangerous - wont happen and nor should it). Problems start when you get to the points and they are set the wrong way - after all thats why you are there in the first place - a failure. Apart from that, it's all plain-sailing! No its not. Each thing takes only minutes - but add them together and it all adds up. And the Supervisor may be above ground on a deep tube so it all takes time and he has a station full of people all asking questions as well. As someone said above, then its slow speed for 2 signals and the trains back up behind real quick. Mal |
Why can't LU cope with a signal failure?
OK - let's see. Dag East unstaffed one time when points needed
securing, Upminster LU-side left in charge of a medically-restricted DMT who could only do the "desk", emergency lights in cars can be just two tubes (like how dark it sometimes gets over rail gaps) - there are no tunnel lights at night in the open of course, the supervisor ar Rayners whom I met recently who admitted he's never been familiarised at that location in over 2 years!!! (his fault or his DSMs? Result same in any case!). |
Why can't LU cope with a signal failure?
wrote in message oups.com... OK - let's see. Dag East unstaffed one time when points needed securing, Upminster LU-side left in charge of a medically-restricted DMT who could only do the "desk", emergency lights in cars can be just two tubes (like how dark it sometimes gets over rail gaps) - there are no tunnel lights at night in the open of course, the supervisor ar Rayners whom I met recently who admitted he's never been familiarised at that location in over 2 years!!! (his fault or his DSMs? Result same in any case!). Ok so you have some incidents. Can you supply dates? Was it recently or a long time ago? Is it still the same now? If it is and you are an LU employee, by your knowledge of these things you become complicit if you dont report them on. So who to you ask? CIRUS is still operating albeit not quite the same. And Im sure HMRI would be interested. If your not LUL- get onto HMRI. With regard to Dag East with med restricted DMT. I dont know that area at all so i only make general comments. The 'desk' is quite capable of being run by a med restricted person. Its not a safety critical position and surely you must agree that the desk man can't leave - who would be available to co-ordinate the T/Ops if he did. The last person you would want to leave there position is the 'desk' person. Like i say - i dont know that area or working practices, they may be different to places i am familiar with. I dont doubt you bit perhaps we see it from different perspectives. The Rayners SS, its his fault in the first instance, then his DSM should also be responsible - but he cant be with them 24/7. However at the money the SS is on surely he has the intelect to realise he needs it. Everybody must take responsibility for there actions. He could easily be familiarised when he takes the shift over, it does not need a manager to do it. I can only hope you expressed your concern/disgust to him/her at the time. After all, it could be your life in his/her hands one day. What stock have only 2 tubes on batteries? Educate me. Again stock i know has more than that. You got me on the no tunnel lights in the open........been underground for too long i think...time for a change! Lets sort it..... Mal |
Why can't LU cope with a signal failure?
[+] For example, on 1953-04-08 twelve passengers were killed in a
collision just in rear of signal A491, which had failed. The driver of the rear train failed to control his speed after tripping past A489. And in other news hundreds died in Comet airliner crashes caused by metal fatigue. Good thing we didn't keep on pressuring aircraft and flying so high else who knows how many other people would have died! Are you seriously suggesting that 50 years later the controllers still wouldn't know that there was a train on the section ahead of a stuck signal and so to warn the driver behind? B2003 |
Why can't LU cope with a signal failure?
In article .com,
Boltar writes [+] For example, on 1953-04-08 twelve passengers were killed in a collision just in rear of signal A491, which had failed. The driver of the rear train failed to control his speed after tripping past A489. Are you seriously suggesting that 50 years later That was the date that I could find most quickly when writing that posting. I am aware of other collisions in the same area much more recently, but I'd have to dig through a fair amount of paper to find the details. the controllers still wouldn't know that there was a train on the section ahead of a stuck signal and so to warn the driver behind? The driver who passed A489 knew there was probably a train ahead of him (it could have moved off). Nevertheless he failed to control his speed and killed 12 people as a result. It is incidents like this that led to the introduction of Speed Control After Trip. The specific device which you think should be removed. -- Clive D.W. Feather | Home: Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org Fax: +44 870 051 9937 | Work: Please reply to the Reply-To address, which is: |
Why can't LU cope with a signal failure?
Boltar wrote:
[+] For example, on 1953-04-08 twelve passengers were killed in a collision just in rear of signal A491, which had failed. The driver of the rear train failed to control his speed after tripping past A489. And in other news hundreds died in Comet airliner crashes caused by metal fatigue. Good thing we didn't keep on pressuring aircraft and flying so high else who knows how many other people would have died! Are you seriously suggesting that 50 years later the controllers still wouldn't know that there was a train on the section ahead of a stuck signal and so to warn the driver behind? Much of the railway works on Automatic signals. These are not repeated in any signal cabin or control room. To do so would be wasteful of taxpayers money. |
Why can't LU cope with a signal failure?
The driver who passed A489 knew there was probably a train ahead of him
(it could have moved off). Nevertheless he failed to control his speed and killed 12 people as a result. If there was a train in the section ahead of him then why was he given permission to move past the signal into that section in the first place as it seems to me the signal would have been red at that point even if not broken. AFAICS all that was required was for control to tell the driver to remain at said signal until the block ahead was clear, this isn't rocket science. B2003 |
Why can't LU cope with a signal failure?
Boltar wrote:
The driver who passed A489 knew there was probably a train ahead of him (it could have moved off). Nevertheless he failed to control his speed and killed 12 people as a result. If there was a train in the section ahead of him then why was he given permission to move past the signal into that section in the first place as it seems to me the signal would have been red at that point even if not broken. AFAICS all that was required was for control to tell the driver to remain at said signal until the block ahead was clear, this isn't rocket science. Because it's an automatic signal, (that means it works autimatically). It normally shows green, proceed. Causes of it remaining at red, danger include reasons additional to a train being on that particular section of track. Such reasons include, a defective signalling circuit, a broken rail (although that's not guaranteed to keep the signal at danger) or perhaps flooding of the track. Being in an automatic area no signalbox or control centre has control over it and so the signaller or controller cannot tell the driver what the problem is. Therefore the driver cannot be "given permission". S/He waits one minute and if the signal fails to clear there is a standing instruction to proceed. This is the "stop and proceed" rule. This rule relied on the driver travelling at such a speed that he can stop before reaching an obstruction. Failure of a number of drivers to comply with this simple rule resulted in a speed limiting device being fitted so that after the tripcock is activated a maximum speed of 10mph is all that's available for (IIRC) 5 minutes. Hence delays build up. Even if the whole railway were controlled by signallers there would still be delay. |
Why can't LU cope with a signal failure?
the driver what the problem is. Therefore the driver cannot be "given
permission". S/He waits one minute and if the signal fails to clear there is a standing instruction to proceed. This is the "stop and proceed" rule. So in other words the driver should only wait for 1 minute at any red light since the line controllers don't have a clue whats going on and wouldn't know if train A was in front of train B. In which case how come I've been in trains stuck at non broken red lights for up to 10 minutes at various times? Perhaps its about time LU moved into the 20th century , never mind the 21st and actually had electronic line maps in the controllers rooms so they had a bloody clue where the trains on the line they're controlling actually are. B2003 |
Why can't LU cope with a signal failure?
"Boltar" wrote in message oups.com... the driver what the problem is. Therefore the driver cannot be "given permission". S/He waits one minute and if the signal fails to clear there is a standing instruction to proceed. This is the "stop and proceed" rule. So in other words the driver should only wait for 1 minute at any red light since the line controllers don't have a clue whats going on and wouldn't know if train A was in front of train B. In which case how come I've been in trains stuck at non broken red lights for up to 10 minutes at various times? Perhaps its about time LU moved into the 20th century , never mind the 21st and actually had electronic line maps in the controllers rooms so they had a bloody clue where the trains on the line they're controlling actually are. B2003 Boltar...... The L/C and signal guys dont have a visual of whats on the track. All they have is a line diagram that shows a light when a train is occupying a section of track. That shows a train is there. A signal failure manifests itself by.......thinking a train is in the section ahead of the signal. So the signal goes red, thus stopping you and everyone else. The diagram shows a train in the section, if it didnt the signal could go green. So the first the L/C knows about it is when your train calls up and says i've been here and its red. The L/C looks at the diagram and sees a light in the section. He now thinks there is a train there. Before he can authorise anyone to move he has to try and contact the train by radio. If no-one responds he will assume we have a problem. Its not actually a 'signal' failure. Its a track circuit down. Nothing wrong with the signal, its reflecting what it thinks is a train ahead. You may have been stopped for 10 minutes....perhaps you were the 5th train in line. If the T/Op cant contact L/C he then can carry out the appropriate procedure. If its an auto, wait 2 minutes and go at a speed that he can stop....etc etc. If its protecting points then he must contact L/C by any means. If he cant get a direct contact, such as signl phone he nmust wait for a visual/verbal direct communication. They tried the system where trains set off at 2 minute gaps without the hindereance of signals about 100 years ago.....too many crashes....You might be a bit late for a meeting or dinner...but this is safe. Mal |
Why can't LU cope with a signal failure?
They tried the system where trains set off at 2 minute gaps without the
hindereance of signals about 100 years ago.....too many crashes....You might be a bit late for a meeting or dinner...but this is safe. I'm not suggesting ignoring signals, I'm just trying to figure out the logic behind the system they use now. Signal has failed so go slow across the next 2 working signals. Don't get it. Signals don't fail to green (supposedly) so if the signal after the failed one is green why on earth go slow past it, why not just go normal line speed? It just seems OTT. B2003 |
Why can't LU cope with a signal failure?
Boltar wrote:
They tried the system where trains set off at 2 minute gaps without the hindereance of signals about 100 years ago.....too many crashes....You might be a bit late for a meeting or dinner...but this is safe. I'm not suggesting ignoring signals, I'm just trying to figure out the logic behind the system they use now. Signal has failed so go slow across the next 2 working signals. Don't get it. Signals don't fail to green (supposedly) so if the signal after the failed one is green why on earth go slow past it, why not just go normal line speed? It just seems OTT. Because of something called an "overlap". In order to provide protection for the next train ahead the signal is positioned before the start of the track section it controls access to. The length of the overlap varies according to the weight and speed of the trains plus an allowance for bad weather. If driver's resumed normal speed after passing only one signal at clear or caustion there might be another train or other problem withing the overlap. Then no one gets home for tea. If you want to learn about how the underground works, and why it's done the way it is, try http://www.trainweb.org/tubeprune |
Why can't LU cope with a signal failure?
On Tue, 31 May 2005, Brimstone wrote:
Boltar wrote: They tried the system where trains set off at 2 minute gaps without the hindereance of signals about 100 years ago.....too many crashes....You might be a bit late for a meeting or dinner...but this is safe. I'm not suggesting ignoring signals, I'm just trying to figure out the logic behind the system they use now. Signal has failed so go slow across the next 2 working signals. Don't get it. Signals don't fail to green (supposedly) so if the signal after the failed one is green why on earth go slow past it, why not just go normal line speed? It just seems OTT. Because of something called an "overlap". In order to provide protection for the next train ahead the signal is positioned before the start of the track section it controls access to. The length of the overlap varies according to the weight and speed of the trains plus an allowance for bad weather. If driver's resumed normal speed after passing only one signal at clear or caustion there might be another train or other problem withing the overlap. Then no one gets home for tea. According to http://www.trainweb.org/tubeprune/signalling1.htm, signals are linked to the overlap between them and their section, as well as to the section itself (the overlap, being part of the previous section, is also linked to that section, of course). If that's true, there can never be anything between a green signal and the end of its section, in the overlap or not. Thus, it is always safe to go up to full speed at a green signal. No? tom PS This is eerily reminiscent of concurrent computer programs. Things queueing up on a critical section, regulated by wait and signal operations. Such programs are notoriously and fiendishly difficult to write correctly - or to read! PPS Got as far as drawing this much of a highly entertaining diagram before deciding text alone would do: /----O /----O /----O ==== ==================== ==================== ======= ^....^ Thought i'd include it in case anyone feels like drawing pictures and wants somewhere to start! tom -- power to the people and the beats |
Why can't LU cope with a signal failure?
"Tom Anderson" wrote in message h.li... On Tue, 31 May 2005, Brimstone wrote: Boltar wrote: They tried the system where trains set off at 2 minute gaps without the hindereance of signals about 100 years ago.....too many crashes....You might be a bit late for a meeting or dinner...but this is safe. I'm not suggesting ignoring signals, I'm just trying to figure out the logic behind the system they use now. Signal has failed so go slow across the next 2 working signals. Don't get it. Signals don't fail to green (supposedly) so if the signal after the failed one is green why on earth go slow past it, why not just go normal line speed? It just seems OTT. Because of something called an "overlap". In order to provide protection for the next train ahead the signal is positioned before the start of the track section it controls access to. The length of the overlap varies according to the weight and speed of the trains plus an allowance for bad weather. If driver's resumed normal speed after passing only one signal at clear or caustion there might be another train or other problem withing the overlap. Then no one gets home for tea. According to http://www.trainweb.org/tubeprune/signalling1.htm, signals are linked to the overlap between them and their section, as well as to the section itself (the overlap, being part of the previous section, is also linked to that section, of course). If that's true, there can never be anything between a green signal and the end of its section, in the overlap or not. Thus, it is always safe to go up to full speed at a green signal. No? tom PS This is eerily reminiscent of concurrent computer programs. Things queueing up on a critical section, regulated by wait and signal operations. Such programs are notoriously and fiendishly difficult to write correctly - or to read! PPS Got as far as drawing this much of a highly entertaining diagram before deciding text alone would do: /----O /----O /----O ==== ==================== ==================== ======= ^....^ Thought i'd include it in case anyone feels like drawing pictures and wants somewhere to start! tom -- power to the people and the beats My brain hurts now...... Mal |
Why can't LU cope with a signal failure?
In article , Tom
Anderson writes According to http://www.trainweb.org/tubeprune/signalling1.htm, signals are linked to the overlap between them and their section, as well as to the section itself (the overlap, being part of the previous section, is also linked to that section, of course). If that's true, there can never be anything between a green signal and the end of its section, in the overlap or not. Thus, it is always safe to go up to full speed at a green signal. No? No. In some situations it's as you described: |-O 6 |-O 4 |-O 2 -------+---A---I-------B-------+---C---I-------D-------+---E---I-- 6 green requires A, B, and C all clear. 4 green requires C, D, and E all clear. But on plain line there's unlikely to be separate track circuits, so it's more like: |-O 6 |-O 4 |-O 2 ---------------I------------X----------I------------Y----------I-- 6 green requires X clear. 4 green requires Y clear. I don't believe there are any photos on my web site showing it, but I've certainly seen a signal stay green after a train has passed it until it reaches the overlap block joint. On the Silverlink lines there are places where, because of this, a single class 313 can disappear around a bend before the station starting signal goes back to red. -- Clive D.W. Feather | Home: Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org Fax: +44 870 051 9937 | Work: Please reply to the Reply-To address, which is: |
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