zwk500
Veteran Member
Given the presence of the I278 sounds like it might have been related to a possession and different parts referenced in the WON as a guess.
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Signal berth codes?
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Earle Grey
Member
They are the possession reference numbers imposed in the TD berths from last Friday night/Saturday morning (26/27th July) to show the possession limits. They're aren't there now on TMV, and suspect the data has failed to clear from whichever 3rd party real time viewer you are watching on.
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Vexed
Member
Strange one, both M844 (Musselburgh side) or M841 (Wallyford side) were P278 as your diagram shows but I don't have records from the Train Describer feed of either being cancelled and I also don't have any indication of an outage.
M841 is only showing nothing on Traksy (what cornishjohn used) because it was set to DETS this morning at 0056 then cancelled at 0333. Until DETS got set it would have been incorrectly showing P278, if Traksy/OTT maps/others experienced the same missed data I got.
endofthetunnel
Member
In slightly easier to understand language, the signal berths shown on various open data feeds don’t always match exactly what signallers can see or can use, because they are built by reverse engineering in lots of cases.
There are often ‘hidden’ berths in the system which are either shown only on small monitor displays but not on panels themselves, or even never visible anywhere but present to help the Train Describer system function better.
Either way, if these end up showing data (often during engineering work where trains can move in unusual ways, or during unsignalled movements, or just a signaller mistyping) they often don’t properly get cleared out by signallers or normal trains, sometimes for a very long time.
There were a few like this in one of my boxes which I messaged and got removed from Tracksy to hide these sorts of issues.
There are often ‘hidden’ berths in the system which are either shown only on small monitor displays but not on panels themselves, or even never visible anywhere but present to help the Train Describer system function better.
Either way, if these end up showing data (often during engineering work where trains can move in unusual ways, or during unsignalled movements, or just a signaller mistyping) they often don’t properly get cleared out by signallers or normal trains, sometimes for a very long time.
There were a few like this in one of my boxes which I messaged and got removed from Tracksy to hide these sorts of issues.
alxndr
Established Member
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I think you’re a day out there, Item 278 was from late Saturday night to Sunday morning.
Annetts key
Established Member
Yes, many TD systems have "hidden"/"blind" or "semi-blind" berths. These are not normally shown on signallers displays. But may be shown on technicians displays. Sometimes also shown on additional displays used by other operations staff.
To reiterate what others have said above, it's the shunt signal berths which have the possession notice in them (you can tell this because the little arrow on the ends of the berth is pointing towards the un-filled circle). Many shunt signals don't have berths attached to them at all in the signalling systems, and where they do appear they are sometimes absolutely awful at clearing, to the point where I've excluded a lot of them from the diagram.
They also appear on the Elizabeth Line core. The train appears in a berth with the yellow dotted lines creeping their way across until suddenly the train jumps forward 2-3 berths. I don't know if it's based on track circuits or GPS or some other kind of data, or if it's even the same system as in Eastborne.
Belperpete
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Having watched how they perform as trains arrive and depart, I think the yellow indications actually show that the track is clear. So no yellow indications means there is a train there. Each platform has two sets of indications, one for the inner half of the platform, and one for the outer half of the platform.
As a train arrives, first the yellow dots go out for the outer half of the platform, then the whole platform, then they turn on again for the outer half of the platform once the train is on the inner section. A similar thing happens in reverse as a train departs: initially the inner dots are turned off, then both inner and outer as the train moves out, then the inner dots turn on, and then the outer dots too once the train has left the platform.
Off topic, but thanks to members highlighting the site, I've spent many happy hours watching various diagrams on opentraintimes. The Kings Cross-Cambridge choreography is a personal favourite as the Ely/Lynn fast (1Txx) chases the (too rarely on time) Thameslink (9Sxx), with both hoping to pass the Cambridge/Letchworth stopper (2Cxx) just before the Welwyn 2-track, the fast in turn passing the Thameslink which stops at Stevenage/Hitchin. It then needs the previous stopper to be on time as both close in on Cambridge.
What puzzles me are the various signal representations. Could anyone explain the differences between:
* the standard "lollipop"
* the right-angled "lollipop"
* the right-angled quadrant "lollipop"
* the double "lollipop" (standard + quadrant)
* other variations towards Moorgate or on the Lizzy Line
Thanks.
What puzzles me are the various signal representations. Could anyone explain the differences between:
* the standard "lollipop"
* the right-angled "lollipop"
* the right-angled quadrant "lollipop"
* the double "lollipop" (standard + quadrant)
* other variations towards Moorgate or on the Lizzy Line
Thanks.
Belperpete
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Without specific examples to go on, I think these are main aspect signal, stop board, shunt signal, and main aspect signal with a subsidiary shunt signal. On the line toward Moorgate, there are also some ETCS arrow marker boards (effectively ETCS stop boards).
Edit: do you have some examples of the double lollipop? On a quick scan, many of the signals that I am sure are colour-lights with a subsidiary are just shown as a single lollipop. The only double lollipops that I can quickly see are where there is an ETCS arrow board on the same post as a colour light.
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Gloster
Veteran Member
The one that looks like a quarter of pie is a shunt signal. Limit of shunt boards are a red dot in a square, usually marked LOS. The number 2 approaching Bury St Edmunds from Kennett should be a normal signal with a subsidiary aspect.
On the Ipswich map many of the station's signals are shown as doubles (circle + quadrant). Main + subsidiary shunt makes sense. Thank you.
Gloster - thanks for confirming my undeclared guess re the square + red dot.
The way the Felixstowe line recovers from freight delays, sometimes needing to cancel a passenger train also interests me!
The shunts are used heavily for shunting moves of passenger units as well as freight. As far as I'm aware, there's only 3 tracks available for passenger service at the goods junction which are the top 3 (Down, Up, and one marked L which I don't know the name of). I've never seen the fourth one used by passenger trains, even for shunting moves.
The Felixstowe services have quite long dwell times so they can easily catch up a 20 minute delay in one trip. It seems to be king on the single track sections and freight is lowest priority. I've seen freight run onto the wrong* side at Derby Road to allow a passenger train to overtake without a platform alteration.
* It's bi-directional for this purpose, but it is the right-hand track.
AIUI, the right angled ones without berths tend be repeaters or signals protecting level crossings. Right angled shunt signals are usually just because there is no berth (see CO804 at Ipswich). I'm not entirely sure the reason for this, but it tends to be for short sidings with only one set of points.
You may also tend to see points lead to an area with no berth, this can be the same thing or can be a set of points designed to derail a train safely rather than have it run onto an active line (flank protection).
zwk500
Veteran Member
This indicates a standard main-aspect signal. Whether this is capable of showing 1, 2, 3, or 4 aspects (R/Y/YY/G) will depend on the local area. The data feed normally just indicates 'On' (Red) or 'Off' (Y/YY/G). Some sites work out what the aspects would be from the sequence of 'Off' aspects.
Not sure what you mean by the right-angled version, but this:
Is a limit of shunt signal, it's a fixed display (sometimes just a sign) that indicates the limit of movements authorised from shunt signals.
This represents a shunt signal with no associated main aspect.
This is a main-aspect signal with a subsidiary aspect for shunting routes (i.e. towards yards/sidings) or permissive movements (attaching, sharing the platform).
Crossrail Uses an in-cab signalling system call CBTC, which has 'block markers' rather than traditional signals. On the Crossrail core, the CBTC marker boards use the same Yellow wedge on a blue background as used in TVM signalling used on French High-speed lines (and HS1/Channel Tunnel). The use of this design is presumably to help make it clear when trains are moving between CBTC and ETCS, when ETCS is ftitted.
Moorgate uses ETCS Level 2 in-cab signalling. On OpenTrainTimes, the Moorgate line is shown slightly incorrectly, with a marker board below a signal.
Since last may, there is no physical green signal on the trackside between Moorgate and Drayton Park now. Other sites such as SignalMaps show the arrows changing from Yellow to Green to indicate a proceed 'aspect'. For a while, there was both signals and block markers to allow training to take place.
see also: https://signalmaps.co.uk/#kingsx:1061
David 90825
Member
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Point of Obstruction (Working to and From)
ollyrogers
Member
I noticed one earlier just east of Swanley with 1TRN as a code. Does anyone know what this is? Possibly a shunt (TuRNback)?
endofthetunnel
Member
It’ll be to remind them of One Train Working of some sort, but I’m not familiar with the location.
If its in a siding it probably means 1 train. Often would be 1*in to say the same thing
The ones for this that I see are UNIT, WAGN/WAGS, LOCO, STBL, a class number, or just an old headcode.
Either there's a train there, or the signaller is reminding themselves that they need to specially watch the operation of track circuits for the next train on that line following a possession/line block affecting safety of the line. I've seen it be used for both.
Or sometimes a time, presumably used during degraded working
A time can be lots of things. In Didcot it tends to be the opening time for the yard. It's often the scheduled end time for a possession. In station platforms it's usually the time that train is due out in the morning (since that's more useful than the headcode overnight). I would have thought the same applies to sidings.
Carriage sidings.
rower40
Member
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As in “If it’s not too much trouble, would the signaller please route this train to the Carriage Sidings?” In four letters.
RailwayRookie
Member
Most likely just to clear the previous trains headcode and avoid confusion. Same reason you see FUEL, JUBI, SHNT in Norwich for the respective Sidings a lot of the time.