This might be a simple question for experienced Board members to answer... How does the network know what train is where, and where it is going at any given moment - for example, trains travelling on a main line need to have points set so they don't go to the wrong place. But if a train is delayed, then the people controlling the line need to know not to set the points too early or else another train might go down the wrong line. I assume it's not done by witchcraft?
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Tracking trains
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The signal boxes track trains by electronic track circuits or axle counters etc and can identify trains by a unique headcode. This headcode has a letter (ie 1C34). The letter is the route code so the signaller can see which train needs to go where. So a signaller controlling a busy junction knows that headcodes with A,C,F or V need to turn left at the junction and those with B,G,H or N need to go straight on for example. Therefore if one is running late the signaller can still see which approaching trains want to go where and set the road accordingly.
They still get it wrong sometimes though, in which case it is down to the driver to notice and stop to challenge the route. And that is just down to the drivers route knowledge to notice the signs (for example at a low speed junction the driver may be expecting a double yellow at a specific signal to suggest the correct route may be set-if they see a green there then they knw it can't be.
Hope this helps and makes sense!
They still get it wrong sometimes though, in which case it is down to the driver to notice and stop to challenge the route. And that is just down to the drivers route knowledge to notice the signs (for example at a low speed junction the driver may be expecting a double yellow at a specific signal to suggest the correct route may be set-if they see a green there then they knw it can't be.
Hope this helps and makes sense!
Class377/5
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Every single train has unique code. If I remember correctly its 10 digits long but front line staff generally deal with a 4 digit version. Ie 1W94 which software can see. This short digit is also displayed on the signalling panels/screens and signallers use it to direct their trains. Signals get simplifiers which are the code to ensure they are routed as book.
This way time doesn't actually matter so much when controlling the trains. However the 4 digit codes may appear more than once over the same day but will be spaced they never meet. Ie 0205 train and 1600 train.
Eagle
Established Member
One letter and five numbers, actually.
87015
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The UID is used by basically nothing operationally, the full headcode is far more important. Not quite sure why they don't do away with it and push the few systems which use it to accept headcodes.
Kryten2340
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What if the driver got it wrong failed to notice the points were set incorrectly and took the wrong route. Would the train reverse, travel to the nearest siding to change ends and war back or would the passengers be detained?
Cherry_Picker
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If he didnt sign the other route, then yes, that would have to happen. If he did sign the other route then it would almost certainly still happen unless the "diversion" was relatively minor and taking it would cause less disruption than stopping the job to set back. As for how it would specifically be worked? Well, it depends entirely on where it is, if there are any level crossings in the way, what time of day it is (there are more trains running around in the peaks) and whether the section behind is occupied or not. Case by case basis.
Yes. Could be any of the above, depending on the location/situation. Although not 'reverse' as such, change ends and make a wrong direction movement.
syorksdeano
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I believe this happened recently and a passenger train ended up taking a detour via a power station
I think that incident was legitimate as the main line was blocked - passenger trains can take odd routes through goods loops and also recently one went through a wash road this can only be done with prior permissinion from the signaller
Class377/5
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No it's not. I used the 4 digit for my work all day long.
First digit is for class type, second ID-ing letter and two numbers.
UID is the longer code not used day to day to control trains.
Wrong routing happens very frequently-I have lost track of the number of times I have been sent the wrong way. Never taken one yet though, fingers crossed!
It's not always just about going to the wrong place, it can also be a problem with certain stations which only have platform on certain lines, for example there are no platforms on the up fast line at Wandsworth common or battersea park so if you come up from Croydon nd are routed onto the up fast with an all stations stopper you would accept it with no problems but must make sure you are crossed back to the slow at balham north or else can't stop at Wandsworth or battersea. Similar if working empties to Selhurst depot you must remember that balham south is the last place you can be crossed to the down slow to get into the depot.
It's not always just about going to the wrong place, it can also be a problem with certain stations which only have platform on certain lines, for example there are no platforms on the up fast line at Wandsworth common or battersea park so if you come up from Croydon nd are routed onto the up fast with an all stations stopper you would accept it with no problems but must make sure you are crossed back to the slow at balham north or else can't stop at Wandsworth or battersea. Similar if working empties to Selhurst depot you must remember that balham south is the last place you can be crossed to the down slow to get into the depot.
Eh? There is a platform, but there is also a requirement to confirm with the signaller that the gates are unlocked if you're stopping there. (Is that what you meant?)
As far as I have always been told the gates will never be unlocked unless there are planned engineering works, but even then they have always just run non stop and told people to go to clapham and change there. Also no DOO equipment at the platform (the monitor case is empty or they are broken or something, they are never on anyway. )
But you certainly would want to treat it as a wrong route at balham if expecting to stop there and routed onto the fast.
But you certainly would want to treat it as a wrong route at balham if expecting to stop there and routed onto the fast.
Strat-tastic
Established Member
hock: :?Surely not. So if you're going too fast for the points you're not expecting to be using and cannot slow down in time, what happens...? Or am I missing the point (
) somewhere?I've stopped there during engineering works a couple of times (over the last Christmas period was the last time I think), the monitor case is as you say empty, so only 377s are supposed to stop there (in theory).
I agree though, I would query a route onto the fast at Balham if stopping at Wandsworth Common, same as a route onto the Up Fast at Purley if booked to stop at Purley Oaks.
I don't think a train should end up in such a situation as above. You'd either get routed on the faster line and probably be travelling about that anyway or routed to a diverging line and end up under caution on approach locking. Of course, the train may not be able to stop before such signal and may end up overrunning the junction.
That's my understanding of it anyway
That's my understanding of it anyway
Surely not. So if you're going too fast for the points you're not expecting to be using and cannot slow down in time, what happens...? Or am I missing the point (
Stop at the controlling signal if possible; if not, bring the train to a stand, contact the signaller and follow his/her instructions.
Cherry_Picker
Established Member
Surely not. So if you're going too fast for the points you're not expecting to be using and cannot slow down in time, what happens...? Or am I missing the point (
Chances are you might derail, which would be very bad for everybody involved. I dont know whether this has just gone without saying in the thread so far but it is worth highlighting that the driver has a bit more indication than which way the points are facing as to where he is headed. There are whole sequences of signals leading up to junctions and you expect to see them show certain aspects in a specific order to send you on the route you need to take. Again, it depends on the location and the speed over the junction, but at higher speed junctions (increasingly the norm) you will get flashing yellow signals before the junction signal showing which way the route is set. If you see a green at that signal where you were expecting a flashing yellow then you know you have been wrong routed so you stop the train immediately and tell the signaller that you have been wrong routed. Same if you are being brought down to a red signal for a route to clear over a lower speed junction, if there is a green where you were expecting a yellow then again, stop immediately and tell the signaller.
I guess the easiest trap to fall into is when there is a route out of a platform set by a stencil indicator (the sort of signal which just has a letter above it, ie "M" for main or "B" for branch) above a green signal, and you can miss that if you arent careful, particularly as platform duties can be distracting. I have been wrong routed several times and, thankfully, have never taken one yet. When you think of how many trains run over how many junctions every single day then the amount of wrong routes given is absolutely tiny. It is a fraction of a fraction of a percentage point, but it still happens. Usually drivers notice and save for a minute or two delay while the correct route clears and signals time out, passengers are blissfully unaware of it.
Strat-tastic
Established Member
Not all junctions are like this though Cherry Picker - by which I mean we're not always brought down in speed or pre warned by yellows / flashing or otherwise.... Aston in Birmingham is a good example of this : if you're heading south the approach speed is 45mph, followed by a short stretch at 30mph, immediately after this is a 20mph restriction if you're being routed off to the left towards Stetchford, New St Panel can route you round this way under green signals. Despite the graded drops in speed you could still be caught out at the junction and hit it at 30mph if you're not on the ball.... the first sighting of the number one route indicator on the junction signal from the curved approach is quite close.
Hope that makes sense
Cherry_Picker
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Oh, I know there are several examples. It's the same at Bearley on the Stratford upon Avon branch. Heading away from Stratford you are on greens and by the time you get the signal which dictates whether you are heading up the North Warwick to Birmingham or round the single line to Leamington Spa you wont have much room at all to stop before the points. This was only resignalled in late 2010 too!
The maximum differential between the line speed of diverging routes without any form of approach control is 10mph, which is well within the safety margin to prevent a derailment.
If the differential is above 10mph, then some form of approach control is required, almost always a restrictive aspect 'released' to a less restrictive aspect after the train has been on the approach for a set time or distance. Flashing yellows are less common but do the same job without slowing the train as much.
In a small number of instances there are 'splitting distants' where two separate signal heads are provided for one line, with one applying for the diverging route, and one for the straight route. I think these are provided on the Down Main at Airport Jn (GWML).
For cab signalling it is of course easier all round.
If the differential is above 10mph, then some form of approach control is required, almost always a restrictive aspect 'released' to a less restrictive aspect after the train has been on the approach for a set time or distance. Flashing yellows are less common but do the same job without slowing the train as much.
In a small number of instances there are 'splitting distants' where two separate signal heads are provided for one line, with one applying for the diverging route, and one for the straight route. I think these are provided on the Down Main at Airport Jn (GWML).
For cab signalling it is of course easier all round.
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