Signal_Box
Member
Unless it’s a very basic terminal station, I’d bet there is some kind of route / platform indicator.
All signalled permissive moves are via a position light aspect (“calling on”/“shunt signal”/“dummy”), which for a colour light signal, is two diagonal white lights which illuminate next to the (main) red aspect.I do believe at most stations with permissive working drivers have to be "called on" to the platform in advance. I think this happens at most terminals and is my understanding but maybe drivers could advise what happens in practice?
All signalled permissive moves are via a position light aspect (“calling on”/“shunt signal”/“dummy”), which for a colour light signal, is two diagonal white lights which illuminate next to the (main) red aspect.
As Railsigns says, whenever there is more than one route or destination available from a signal, there will be a route or junction indicator. So the driver always knows where the signal has been routed to.
The above applies regardless of if the station is a terminus, a through line, a bay line, or any other line where (signalled) permissive moves are allowed.
So if a driver gets a main proceed aspect (Y, YY or G), the line is clear to the next signal. But if a driver gets a position light proceed aspect, the driver must control the speed of the train such that the train can be stopped short of any other train that may be ahead.
Unless the line speed is low, a signal routed into an occupied section (that is, there is a train ahead in section) will have approach release (approach control). This means it will not clear until an approaching train is on the ‘berth’ track circuit (the track circuit immediately on the approach to the signal) and in some cases, a timer also has to run before the signal will clear. This is to ensure that the speed of the train is reduced.
That works well where the trains that share platforms are all the same length, but not so much where you've got all sorts of different combinations (as found at Lime Street). For example, if your 12-car platform is divided into three equal sections designed around 4-car multiple units, you'll be fine with 4 on top of 8 or 8 on top of 4, but 5 on top of 5 won't go!When I was involved in signalling / interlocking design ( a good few years ago), there was something termed “ Lime Street Control”, the concept being that for regularly used permissive moves, the platform track circuits were split and also the berth track circuit of the approach signal was also split, so in effect these multiple track circuits were termed “measuring” tracks.
This effectively meant that the signaller could see from the panel if the train would be able to fit in the platform behind another.
I recall that if the train was ”measured” to be too long, the signal would not clear.
Signalling Principles may have changed in the last few years of course.
The principal was called “Lime Street Control” after an incident at Liverpool apparently
You can't blame the driver. The purpose of a calling signal signal is to inform the driver the platform ahead is already occupied so drive the train to stop short of an obstruction.Depending upon the location, blame could also be attributed to the driver for accepting a route into an occupied platform if their train is longer than can be accepted by a calling on signal.
Sometimes a driver will call the signaller to confirm the length of a train already in a platform if their train is longer than the minimum length that a calling on signal can be given for
Could I suggest driver error rather than signalling in this instance, permissive working presumably and the driver should have been proceeding at a slow speed so that he should be able to stop clear of any obstruction.I remember waiting for a train at Man Vic back in about 1978, a long curved platform. A small dmu left heading east just as my loco hauled train came barrelling round the bend and stopped well overlapped with where the dmu was. I still remember thinking that didn't look right, if the dmu had stalled or missed a gear there would have been a collision. Makes you wonder what happened to the signalling.
You can't blame the driver.
Agree thats a fair scenarioAs said, depending on the situation some blame can be attributed to the driver. Eg If the platform holds 8 cars and you are driving 8 cars and you proceed on a calling on.
Interesting comment. I think one reason I could never do the job is driving and not being able to stop where you can see, as is how to drive a road vehicle. Driving in fog at full speed, eeeekk.Could I suggest driver error rather than signalling in this instance, permissive working presumably and the driver should have been proceeding at a slow speed so that he should be able to stop clear of any obstruction.
Lime Street control related to loco hauled working. The platform approach signal measuring track circuit was long enough to allow for two locos (to allow for double heading) to drop onto a train with a calling on aspect. Anything longer and the signal wouldn't clear at all. It didn't attempt to cover combinations of multiple units.That works well where the trains that share platforms are all the same length, but not so much where you've got all sorts of different combinations (as found at Lime Street). For example, if your 12-car platform is divided into three equal sections designed around 4-car multiple units, you'll be fine with 4 on top of 8 or 8 on top of 4, but 5 on top of 5 won't go!
TOCs' defensive driving policies can also be a problem, if drivers are instructed to stop further back from signals and thus not fitting entirely within the measuring track circuit!
Depending on platform length and operational requirements, Lime Street Control could be more flexible than you've described. With two track circuits in the platform line and two measuring berth track circuits at the signal, it was possible to admit a second train of, say, four cars' length into a partially occupied platform, while also ensuring that no more than two locos could approach a fully occupied platform.Lime Street control related to loco hauled working. The platform approach signal measuring track circuit was long enough to allow for two locos (to allow for double heading) to drop onto a train with a calling on aspect. Anything longer and the signal wouldn't clear at all. It didn't attempt to cover combinations of multiple units.
I recall waiting for my train to Newcastle, which I reserved as a Voyager, instead a HST pulled into Platform 3 at Glasgow Central. Platform 3 can really only handle a 6 coach train maximum, so the rear power car and the two first class carriages were all hanging off, meaning the points were blocked.
When I was involved in signalling / interlocking design ( a good few years ago), there was something termed “ Lime Street Control”, the concept being that for regularly used permissive moves, the platform track circuits were split and also the berth track circuit of the approach signal was also split, so in effect these multiple track circuits were termed “measuring” tracks.
This effectively meant that the signaller could see from the panel if the train would be able to fit in the platform behind another.
I recall that if the train was ”measured” to be too long, the signal would not clear.
Signalling Principles may have changed in the last few years of course.
The principal was called “Lime Street Control” after an incident at Liverpool apparently
I recall the driver was on their phone (presumably to control) after pulling in saying that she just took a HST into Platform 3. We had a 12 minute delay while they got us ready to go, presumably manually setting the points.That's the sort of thing that should be covered by a driver's route knowledge and ought to have been challenged by the driver.
Maybe busy terminal platforms need CCTV for the signaller to see whats occuring.The signal box had a view of the station and service trains were using the occupied platform (as well as all other available platforms)
The signal box had a view of the station and service trains were using the occupied platform (as well as all other available platforms)
Same here, does no harm to double check what you're going on top of. The signallers I've spoke to have always been OK about it too.If I receive a position light when being signalled into a platform I ring the signaller to confirm the available platform length for my unit. Every time.
It depends on the scenario. If it’s a through service and they’ve been put on top of something the driver would have to take some responsibility.You can't blame the driver. The purpose of a calling signal signal is to inform the driver the platform ahead is already occupied so drive the train to stop short of an obstruction.
Seems to me just an operating incident that you want to avoid but one of those things that occasionally happen. Of course when signallers could look at the box window and see what was going on they may have had better knowledge rather than sitting remotely in a front of a VDU.