Reminder: SOME scenarios for this series (mainly maintainance) were mock for viewers excitement...... .
Like today's track circuit failure
Talking of that, is there no way of operating in a platform with a track circuit failure? Couldn't you for instance caution trains in and out and have dispatchers give verbal communications to the signallers that the platform was occupied or not?
Three days to repair a TCF?
Engineering excellence.
Talking of that, is there no way of operating in a platform with a track circuit failure? Couldn't you for instance caution trains in and out and have dispatchers give verbal communications to the signallers that the platform was occupied or not?
I believe that that's what used to happen but there seems to be a collective thought that it's better to stop everything nowadays. If the track circuiting electricity is not working does it mean that the points won't work either so a train cannot be put into the relevant platform?
The electricity was working normally so there's no reason to think that the power supply to points etc was defective. The problem, which is typical of track circuits, was that there was a conductive area allowing the current to leak between the rails and the ground. After at least one other thing was fixed this was traced to worn insulating pads under the rails, which literally required the rail to be lifted out section by section so they could be replaced. One does have to wonder though whether this shouldn't have been picked up earlier and fixed before it became a problem, especially after deterioration of the timbers supporting the platform rails led to a derailment on a previous series.I believe that that's what used to happen but there seems to be a collective thought that it's better to stop everything nowadays. If the track circuiting electricity is not working does it mean that the points won't work either so a train cannot be put into the relevant platform?
The electricity was working normally so there's no reason to think that the power supply to points etc was defective. The problem, which is typical of track circuits, was that there was a conductive area allowing the current to leak between the rails and the ground. After at least one other thing was fixed this was traced to worn insulating pads under the rails, which literally required the rail to be lifted out section by section so they could be replaced. One does have to wonder though whether this shouldn't have been picked up earlier and fixed before it became a problem, especially after deterioration of the timbers supporting the platform rails led to a derailment on a previous series.
I believe that that's what used to happen but there seems to be a collective thought that it's better to stop everything nowadays. If the track circuiting electricity is not working does it mean that the points won't work either so a train cannot be put into the relevant platform?
That's the disappointing aspect - until day 3 they hadn't found a reason, just discovered that tinkering around seemed to make the problem go away.Well, it kept coming back online and then going back on the blink. I think they thought they'd fixed about 3 or 4 times in all only for it to fail again.
That's the disappointing aspect - until day 3 they hadn't found a reason, just discovered that tinkering around seemed to make the problem go away.
As a techie, I'd like to hear more background though. What's the MTBF of the insulators? Should they have been replaced before they failed? If platform 5's are knackered, will all other platforms' insulators be inspected?
To the layman, it appears that everything's left to deteriorate until it breaks and then it's patched up, rather than being pro-actively inspected & renewed on a specific schedule. I'm sure that's not the case, but the programme portrays things that way.
And as for protecting analogue electronics from p155 and **** with a few mats........ I cringe!
In hindsight a failure of the insulating pads under the rails seems very obvious to non-engineering people like me. They would have been the 1st thing I would have checked.
Good job you're not in charge of checking then, as that isn't a sensible thing to be looking for!In hindsight a failure of the insulating pads under the rails seems very obvious to non-engineering people like me. They would have been the 1st thing I would have checked.
I wonder if they could use some kind of current transducer around the rail to see where the track circuit current reduces and therefore where the electricity is "leaking"?
Given that modern signalling systems use software-controlled route setting, it should not be possible to set a route (and therefore points) into a platform that is giving an occupied indictaion. When you think about it, that's an absolute no-no for signalling systems.Talking of that, is there no way of operating in a platform with a track circuit failure?
Given that modern signalling systems use software-controlled route setting, it should not be possible to set a route (and therefore points) into a platform that is giving an occupied indictaion. When you think about it, that's an absolute no-no for signalling systems.
Under older systems of signalling it may have been possible to set up the route and get a train to pass a signal at danger, but even then (in ye olden days) I think that would have needed some very stringent procedure to allow that to happen.
You could set the route but the signal wouldn't clear, just as you can overset for a following train before the preceding one has left the route (as long as it's passed over any points that need to change). Or if the platform has several track circuits and the first one is clear you would get a subsidiary aspect. I don't think automatic route setting systems would set a route if there was an unexpected occupied track circuit.Given that modern signalling systems use software-controlled route setting, it should not be possible to set a route (and therefore points) into a platform that is giving an occupied indictaion. When you think about it, that's an absolute no-no for signalling systems.
Under older systems of signalling it may have been possible to set up the route and get a train to pass a signal at danger, but even then (in ye olden days) I think that would have needed some very stringent procedure to allow that to happen.
Given that modern signalling systems use software-controlled route setting, it should not be possible to set a route (and therefore points) into a platform that is giving an occupied indictaion. When you think about it, that's an absolute no-no for signalling systems.
How do signallers allow more than one train into the same platform then or is just a matter of allowing the driver to pass a red?
only just come on Demand 5 this afternoon
The position light or subsidiary aspect tells the driver to proceed but to be able to stop short of any obstruction, in this case a platform with a train at the far end.
Some stations have multiple track circuits in the platforms and even "measuring tracks" on the approach to the protecting signal so that the subsidiary route will only clear if the approaching train is shorter than the space in the platform. I was involved in the original Automatic Route Setting at Liverpool Street and that was programmed not to send a train into an occupied platform - the signaller could set the route manually.
It was OK until train lengths became less standardised. We discovered this at Kings Cross where the Lime Street Control prevented certain combinations of stock sharing a platform even though there was room in practice.The well known Lime Street Control - with measured track circuit berths. Railway "A level knowledge" - an excellent measure.
Obviously never tried to find a fault on a track circuitLike today's track circuit failure