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ERTMS Operation 26/07/2016 at 11:23 #83795
Gwasanaethau
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Hi all!

I was wondering if anyone had any links to any examples of how ERTMS (level 1 or 2) worked. By this, I mean examples of how the system responds when a train runs over a balise (level 1) or when a movement authority is given/revoked; how and when this happens, and so on. I’ve delved into the world of Wikipedia and YouTube, but I have only been able to find very abstract information (eg “An MA is extended based on the position of the train in front and a safe speed profile is calculated.” (or words to that effect)), or obvious (and annoying!) marketing ‘propaganda’ (eg “ERTMS will revolutionise train signalling and is forecasted to provide an increase in capacity.”).

Does anybody know where I can get more detailed information similar to that available for standard UK signalling (something similar to Clive’s excellent descriptions and examples on his website, for example)?

Cheers!

Mark (Gwasnaethau)

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ERTMS Operation 26/07/2016 at 11:42 #83796
headshot119
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Hi Gareth,

My knowledge of ERTMS only extends to what has been done on the Cambrian route, and the research I did into the system when developing the Shrewsbury simulation. I don't claim to be an expert on ERTMS but have a general understanding of how it works.

ERTMS Level 1 (Without Infill) - This is an overlay over an existing signalling system, so lineside signals are still present. The movement authority is transmitted to the train through the balise at the lineside. So the movement authority can only update as the train passes over a balise.

ERTMS Level 1 (With Infill) - Still an overlay over an existing signalling system, so you still have lineside signals. The movement authority is either transmitted to the train through a continuous loop placed along the track (similar to how the underground works on one of the ATO lines), through extra balises placed (Without infill the balises are placed only at signals; think cheap!), or through radio (aka GSMR). This allows the train to recieve a new movement authority sooner, and thus accelerate quicker if the new limit allows it to.

ERTMS Level 2 - Lineside signals are a thing of the past in theory; however block markers are placed in various physical locations to give a method of degraded working. The position of the train is determined by the balise units at the track side, they are placed at fairly regular intervals and are calibrated so the ERTMS system knows there location (a real pain if a tamper takes one out apparently). Movement authoritys are transmitted to the train via radio (GSMR).

Movement authoritys on Level 2 only exist between block markers, it is NOT a moving block (That's what level 3 will be). So let's have a working example (Level 2); note I've completely made all the IDs up.

MH1000 ---- MH10002 ---- MH1004 ---- MH1006 ---- MH1008.

If I've given your train an MA from MH1000 to MH1008, and the train is just passing MH1000, and I shorten the authority down so you only have it as far as MH1006 the train will automatically recalculate a safe braking curve, and will do nothing if it's within that braking curve.

With the same example, but I shorten the MA so you only have it as far as MH1002 the train will calculate a new safe braking curve, will realise it needs to stop fairly quickly and will brake the train fairly quickly.

With the same example, but I completely cancel the movement authority the train will go straight into emergency braking.

"Platform 1 your Maesteg service. Platform 1A your Aberdare. Platform 2 your London!"
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ERTMS Operation 26/07/2016 at 13:09 #83797
clive
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A few years ago a departure from Aberyswyth almost hit a petrol tanker on a level crossing. If you can find the RAIB accident report, there was a fair amount of detail in it.
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ERTMS Operation 26/07/2016 at 14:21 #83798
TUT
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" said:
A few years ago a departure from Aberyswyth almost hit a petrol tanker on a level crossing. If you can find the RAIB accident report, there was a fair amount of detail in it.
This one:

https://assets.publishing.service.gov.uk/media/547c8fdded915d4c0d000171/R112012_120627_Llanbadarn.pdf

?

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ERTMS Operation 26/07/2016 at 17:44 #83799
Steamer
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" said:
The position of the train is determined by the balise units at the track side, they are placed at fairly regular intervals and are calibrated so the ERTMS system knows there location (a real pain if a tamper takes one out apparently). Movement authoritys are transmitted to the train via radio (GSMR).
So does that mean that there are no track circuits or axle counters on a Level 2 route? That must be tricky over pointwork.

Last edited: 26/07/2016 at 17:45 by Steamer
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ERTMS Operation 26/07/2016 at 17:58 #83801
headshot119
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" said:
" said:
The position of the train is determined by the balise units at the track side, they are placed at fairly regular intervals and are calibrated so the ERTMS system knows there location (a real pain if a tamper takes one out apparently). Movement authoritys are transmitted to the train via radio (GSMR).
So does that mean that there are no track circuits or axle counters on a Level 2 route? That must be tricky over pointwork.
As I understand it the spec doesn't require track circuits or axle counters for a level 2 route. Though the Cambrian is axle countered throughout to aid with train detection, and to provide degraded working methods. The trains still use the balises to determine where they are, and to calculate braking curves.

"Platform 1 your Maesteg service. Platform 1A your Aberdare. Platform 2 your London!"
Last edited: 26/07/2016 at 18:01 by headshot119
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ERTMS Operation 26/07/2016 at 18:24 #83802
Jan
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The usual definition of Level 2 I've encountered is still based on classic train detection via track circuits and axle counters. If the interlocking starts relying on the train determining and transmitting its own position (and also guaranteeing that it hasn't lost a wagon or two along the way) you've already reached Level 3.
Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick.
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ERTMS Operationt 26/07/2016 at 19:13 #83803
mallard1938
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Level 2 in operation on the Cambrian

http://www.opentraintimes.com/maps/signalling/cambrian

Driver interface, so-called "heads-down" style driving. As everything is in front of you on the desk rather than on the lineside.

https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/ETCS_driver_machine_interface.svg/718px-ETCS_driver_machine_interface.svg.png

Level 2 in testing on Thameslink, the new class 700 trains have an automatic train operating (ATO) module fitted so they can drive themselves. Along with traffic management software, it will enable 24 trains per hour through the core.

http://www.opentraintimes.com/maps/signalling/tlk_core

ERTMS Level 3 is a way off, it does away with traditional train detection and used on train equipment and radio.

http://www.trl.co.uk/media/773946/cpr798_-_ertms_level_3_risks_and_benefits_to_uk_railways.pdf

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ERTMS Operationt 27/07/2016 at 11:48 #83808
Jersey_Mike
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I'm still waiting for someone to show how this is more cost effective and/or more reliable than proven technology like coded track circuits. The people who thought wireless technology would be cheap and reliable are the children of those who said we'd all be wearing jetpacks.
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ERTMS Operation 27/07/2016 at 15:33 #83815
Finger
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" said:
ERTMS Level 1 (With Infill) - Still an overlay over an existing signalling system, so you still have lineside signals. The movement authority is either transmitted to the train through a continuous loop placed along the track (similar to how the underground works on one of the ATO lines), through extra balises placed (Without infill the balises are placed only at signals; think cheap!), or through radio (aka GSMR).

Citation needed. I don't think sending MA over radio is possible without Level 2.

" said:
This allows the train to recieve a new movement authority sooner, and thus accelerate quicker if the new limit allows it to.

Not only that, it allows the train to run faster by advising the train of the new MA well in advance (that's how they use it in Slovakia).

" said:
ERTMS Level 2 - Lineside signals are a thing of the past in theory; however block markers are placed in various physical locations to give a method of degraded working

Block markers are not a method of degraded working, they are the main signals governing traffic in full supervision! Passing a block marker without a MA, even if the engine allows you to, is PSAD!

Also, ETCS L2 doesn't preclude lineside signals. They may be there eg. for unfitted trains, maybe giving them more adverse signals.

" said:
If I've given your train an MA from MH1000 to MH1008, and the train is just passing MH1000, and I shorten the authority down so you only have it as far as MH1006 the train will automatically recalculate a safe braking curve, and will do nothing if it's within that braking curve.

What you describe is an ACOA. While it is certainly possible, describing operation in terms of ACOAs and PSADs is severely misleading. Also, it might not be really successful, because the train may be in a radio hole.

" said:
As I understand it the spec doesn't require track circuits or axle counters for a level 2 route.

Yes they do! There must be some automatic vacancy detection and interlocking for ETCS L2 to work. OTOH, ETCS L1 could be quite easily deployed on a line without track circuits, just with signallers observing tail-lamps.

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ERTMS Operation 27/07/2016 at 15:37 #83816
taffy
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Just to add to some of well explain responses.

Level 2 can also have overlay, in fact the initial design for the Great Western Main Line will have Level 2 with signaling to allow for mixed traffic operation.

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ERTMS Operation 27/07/2016 at 15:46 #83818
Finger
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" said:
I'm still waiting for someone to show how this is more cost effective and/or more reliable than proven technology like coded track circuits. The people who thought wireless technology would be cheap and reliable are the children of those who said we'd all be wearing jetpacks.

While running into a real risk of replying to a flamebait, I have to remind you that while there are many successful ATPs based on other technologies (loops, balises, radio), I don't know of any ATP with speed supervision for mixed traffic mainline based on coded circuits. So "proven technology"? I'd say proven wrong.

Last edited: 27/07/2016 at 15:46 by Finger
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ERTMS Operation 27/07/2016 at 16:17 #83819
Jersey_Mike
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" said:
" said:
I'm still waiting for someone to show how this is more cost effective and/or more reliable than proven technology like coded track circuits. The people who thought wireless technology would be cheap and reliable are the children of those who said we'd all be wearing jetpacks.

While running into a real risk of replying to a flamebait, I have to remind you that while there are many successful ATPs based on other technologies (loops, balises, radio), I don't know of any ATP with speed supervision for mixed traffic mainline based on coded circuits. So "proven technology"? I'd say proven wrong.
TVM-430 would be one, but I was specifically referring to the reliance of ETRMS and similar systems of wireless data links for continuous wayside to train communication.

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ERTMS Operation 27/07/2016 at 16:23 #83820
headshot119
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" said:
" said:
ERTMS Level 1 (With Infill) - Still an overlay over an existing signalling system, so you still have lineside signals. The movement authority is either transmitted to the train through a continuous loop placed along the track (similar to how the underground works on one of the ATO lines), through extra balises placed (Without infill the balises are placed only at signals; think cheap!), or through radio (aka GSMR).

Citation needed. I don't think sending MA over radio is possible without Level 2.
The ERTMS level 1 spec quotes Eurobalise + infill(euroloop, radio, or extra balises). I took that to mean the MAs can be sent via radiom but perhaps that isn't the case.


" said:
" said:
This allows the train to recieve a new movement authority sooner, and thus accelerate quicker if the new limit allows it to.

Not only that, it allows the train to run faster by advising the train of the new MA well in advance (that's how they use it in Slovakia).
Indeed and that's what I was trying to convey in the original post.

" said:
" said:
ERTMS Level 2 - Lineside signals are a thing of the past in theory; however block markers are placed in various physical locations to give a method of degraded working

Block markers are not a method of degraded working, they are the main signals governing traffic in full supervision! Passing a block marker without a MA, even if the engine allows you to, is PSAD!

Also, ETCS L2 doesn't preclude lineside signals. They may be there eg. for unfitted trains, maybe giving them more adverse signals.
The level 2 spec doesn't require physical signs to denote block markers as I understand it, but on the other hand it doesn't preclude it. In the Cambrian implementation they've placed block markers at strategic locations, but not at all locations where a block marker exists in the system, this was done specifically to allow degrading working if a train couldn't get a movement authority as I understand it.

" said:
" said:
If I've given your train an MA from MH1000 to MH1008, and the train is just passing MH1000, and I shorten the authority down so you only have it as far as MH1006 the train will automatically recalculate a safe braking curve, and will do nothing if it's within that braking curve.

What you describe is an ACOA. While it is certainly possible, describing operation in terms of ACOAs and PSADs is severely misleading. Also, it might not be really successful, because the train may be in a radio hole.
In the opening post I thought Gareth was asking specifically about what would happen if you revoked an MA, and what the train did when it passed over the balise. Rereading the OP I wonder if Gareth actually meant how was the MA revoked when the train had actually "used it up" for want of a better term.

" said:
" said:
As I understand it the spec doesn't require track circuits or axle counters for a level 2 route.

Yes they do! There must be some automatic vacancy detection and interlocking for ETCS L2 to work. OTOH, ETCS L1 could be quite easily deployed on a line without track circuits, just with signallers observing tail-lamps.
As I understand it Level 2 can be implemented using the eurobalise units as a pseudo axle counter units. Though it was decided this wasn't adequate for a UK implementation.


I don't claim to be an expert, and a lot of this is based off the research I did when I developed the Shrewsbury simulation, as well as talking to various staff who work with the system. What is also to important to remember is as a country we've not gone for the cheapest option to implement ERTMS, we've chosen to have the "optional extras" so to speak.

"Platform 1 your Maesteg service. Platform 1A your Aberdare. Platform 2 your London!"
Last edited: 27/07/2016 at 16:36 by headshot119
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ERTMS Operation 27/07/2016 at 23:00 #83823
Finger
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Ah, apparently it is possible to announce the next signal aspects in ETCS L1 by radio (the next two aspects in specification 3.0.0). No wonder ETCS is so complex.

Quote:
The level 2 spec doesn't require physical signs to denote block markers as I understand it, but on the other hand it doesn't preclude it.

I believe it does require it, at least indirectly. How else would the driver know where to stop? Other than route knowledge or looking specifically for balises, he has to look for trackside markers. The DMI won't show him because of the inaccuracy of the odometry.

Of course, there can be trackside markers placed specifically to accommodate degraded modes, eg. to allow a SR->FS transition earlier in case of a failure.

To add something that may answer Gareth's question, this video might help, although it's ETCS L1 and in Polish. It shows quite well how does the train behave with ERTMS.

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ERTMS Operation 29/07/2016 at 19:11 #83845
Gwasanaethau
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Thanks for all your replies! I didn't think I'd be opening such a can of worms when I started the thread! Sorry about that!

Incidentally, it was actually that RAIB report that got me interested in all of this.

Thanks again,

Mark (Gwasanaethau).

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ERTMS Operation 12/02/2017 at 03:49 #93049
Puro
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Jersey_Mike in post 83819 said:
" said:
" said:
I'm still waiting for someone to show how this is more cost effective and/or more reliable than proven technology like coded track circuits. The people who thought wireless technology would be cheap and reliable are the children of those who said we'd all be wearing jetpacks.

While running into a real risk of replying to a flamebait, I have to remind you that while there are many successful ATPs based on other technologies (loops, balises, radio), I don't know of any ATP with speed supervision for mixed traffic mainline based on coded circuits. So "proven technology"? I'd say proven wrong.
TVM-430 would be one, but I was specifically referring to the reliance of ETRMS and similar systems of wireless data links for continuous wayside to train communication.

TVM430 is highly dependent of KVB for complex layouts

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ERTMS Operation 11/08/2017 at 12:09 #100975
Jriver
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Hi Gareth

You can find a whole raft of technical information on the ERA's website (or whatever they are calling themselves this week).

Specifically, the SRS Subset 26 Chapters 3, 4, 5 and 6 are quite informative.

Bear in mind also that the Cambrian was based on baseline 2.3 - things have moved on significantly since then, we are now up to Baseline 3.6 (which apparently wont be tinkered with now 'for at least 10 years' so that suppliers can develop their products without fearing another update).

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