First ETCS train operates on the East Coast Mainline

[najaB]

There's a misunderstanding here. What the DMI displays is the same in Level 1 as in Level 2 (except for the Level icon). The difference is that Level 1 uses switchable balises in the four foot to transmit info regarding the End of Authority (EoA) etc. to the train, much like GW-ATP, in effect telling the train what the next signal aspect is. The info regarding the EoA is therefore only updated when the train passes over a balise group.

Whereas Level 2 uses the GSM-R datalink to transmit this info from the radio block centre (RBC - the signal box if you like) to the train. So if a signal ahead steps up/the section ahead clears, the EoA is updated almost instantly. In Level 2, the balises are fixed, transmitting data on position, national values etc. but nothing about where the EoA is - that info comes from the RBC via GSM-R

The transmission of data to the train is therefore intermittent with Level 1 but continuous with Level 2. This is reflected in the icons for each level: the Level 1 icon has a broken line indicating intermittent, while the Level 2 icon has a solid line indicating continuous.

Neither relies on linside signals strictly speaking, but I can't see much point in a 'signals away' implementation using Level 1.

Thanks for this.

 

[TurboMan]

Level icons as mentioned in my earlier post. Level 1 (dotted line) = intermittent data transmission. Level 2 (solid line) = continuous.

 

[_toommm_]

Apologies for my ignorance, but is ETCS clever enough to know the difference between, say, a 700 and a freight train? If a freight train is following a 700, is it clever enough to space it much further in response to its lesser brake ability, versus, say, an 80x following a 700?

 

[najaB]

Apologies for my ignorance, but is ETCS clever enough to know the difference between, say, a 700 and a freight train? If a freight train is following a 700, is it clever enough to space it much further in response to its lesser brake ability, versus, say, an 80x following a 700?

Yes. Choosing the braking profile of the train is part of setting up the cab at the start of a driver's shift.

 

[TurboMan]

Apologies for my ignorance, but is ETCS clever enough to know the difference between, say, a 700 and a freight train? If a freight train is following a 700, is it clever enough to space it much further in response to its lesser brake ability, versus, say, an 80x following a 700?

In short, yes. On units, the braking characteristics are part of the data the onboard system uses to calculate braking curves; although the driver enters the train length during Start of Mission (SoM), the braking data is fixed according to the unit type.

I assume it's similar for freight but I think there's a requirement for the driver to enter braking data manually because this varies according to the consist of the train.
.

 

[_toommm_]

Yes. Choosing the braking profile of the train is part of setting up the cab at the start of a driver's shift.

In short, yes. On units, the braking characteristics are part of the data the onboard system uses to calculate braking curves; although the driver enters the train length during Start of Mission (SoM), the braking data is fixed according to the unit type.

I assume it's similar for freight but I think there's a requirement for the driver to enter braking data manually because this varies according to the consist of the train.
.

Very interesting, thank you both. So if I was a freight driver with a 66 and a trailing load of 2,000 tons, I would enter that and it would then know how fast I can go from 60 to 40 to 20 to 0, and adjust my distance between the train infront accordingly.

 

[snowball]

Presumably a freight train driver also has to enter the train length? So that it can know when the whole train has come out of a speed restriction.

 

[TurboMan]

Presumably a freight train driver also has to enter the train length? So that it can know when the whole train has come out of a speed restriction.

Yes that's correct. The ceiling speed on the DMI will increase when the rear of the train clears an increase in line speed, so yes, the onboard system needs to know train length regardless of whether it's freight or passenger.

 

[OscarH]

The driver needs both a Movement Authority (MA) on the DMI  and a proceed aspect on the signal. Proceeding with only one, MA or signal, is a SPAD.

Is this one of those instructions that's area specific? Can understand it on the GW where the ETCS "sections" (sorry can't remember the proper term) match the conventional signalling blocks, but on something like Thameslink (as I understand it at least) there are often multiple ETCS sections compared to the blocks in the conventional overlay, so passing conventional signals at red would be necessary wouldn't it

 

[bahnause]

If that's the case on Thameslink, then it's unique on that ETCS implementation and highlights the future problem arising from each implementation having its own idiosyncrasies (including 'national' values, which are anything but national): what happens when the dots are joined and drivers have to cope with slightly different operating principles depending on which part of the network they're on?

This principle with different operating procedures is already a problematic issue today. In my catchment area alone, I run Level 2 routes and Level 1LS. Even the behavior within the Level 2 routes in the same country depends on which software version of the rolling stock interacts with which software version of the infrastructure. Depending on the software and manufacturer of the hardware used, the readings on the displays are also different. This goes so far that the brake application points on Alstom on-board units are always based on the maximum permissible speed, whereas on Siemens on-board units they are based on the current speed. This is an enormous difference for the train driver.

Even with Level 1LS, there are significant differences depending on the software version. A vehicle of the same design with a different software version can differ in display and behavior.

ETCS is a standardization of the hardware, but not a standardization of the operating procedures. In cross-border traffic, it therefore cannot solve the problem of completely different regulations in the various countries.

 

[starlight73]

on something like Thameslink (as I understand it at least) there are often multiple ETCS sections compared to the blocks in the conventional overlay, so passing conventional signals at red would be necessary wouldn't it

Belperpete (upthread) thinks that Thameslink signals turn blue instead of red here (when an ETCS train is authorised to pass a signal that would be at red for a conventional train).

In some implementations of ETCS, the signals are switched to show a special ETCS aspect (often blue) to avoid confusing drivers by the conventional aspects. For example, the ETCS may allow a train to proceed when the conventional signalling wouldn't. It could be confusing for the driver to get a red aspect in such a situation. I understand that the Thameslink signalling works like this.

someone on the signalbox forum thinks they turn yellow instead of blue - whichever colour, it sounds like the signalling system detects when an ETCS train is approaching the signal and changes the aspect so the train isn’t going to pass a red signal.

Thameslink core – The Signal Box

signalbox.org

a train running in ERTMS L2 can receive a movement authority to move into a section between two signals when the train in front is passed the next block marker but not passed the next signal, when the system gives this movement authority the signal at which the train is standing will also display a yellow aspect into the forward section

 

[OscarH]

Belperpete (upthread) thinks that Thameslink signals turn blue instead of red here (when an ETCS train is authorised to pass a signal that would be at red for a conventional train).



someone on the signalbox forum thinks they turn yellow instead of blue - whichever colour, it sounds like the signalling system detects when an ETCS train is approaching the signal and changes the aspect so the train isn’t going to pass a red signal.

Thameslink core – The Signal Box

signalbox.org

Ah interesting, have never seen blue, but yellow makes sense. Wasn't aware the conventional signals would react to such things

 

[najaB]

Ah interesting, have never seen blue, but yellow makes sense. Wasn't aware the conventional signals would react to such things

Maybe the driver who saw a blue signal was exceeding the speed restriction by a considerable margin?

(For anyone who isn't a science nerd - if you travel towards a yellow signal at something like 190,000 km/h it would appear to be blue)

 

[ThisIsSurbiton]

someone on the signalbox forum thinks they turn yellow instead of blue

It's yellow as far as I know. Other systems use every variation you can imagine - blue, red with flashing white, blank, white cross - you name it!

Maybe the driver who saw a blue signal was exceeding the speed restriction by a considerable margin?

 

[Bald Rick]

In some implementations of ETCS, the signals are switched to show a special ETCS aspect (often blue) to avoid confusing drivers by the conventional aspects. For example, the ETCS may allow a train to proceed when the conventional signalling wouldn't. It could be confusing for the driver to get a red aspect in such a situation. I understand that the Thameslink signalling works like this.

If that's the case on Thameslink, then it's unique on that ETCS implementation and highlights the future problem arising from each implementation having its own idiosyncrasies (including 'national' values, which are anything but national): what happens when the dots are joined and drivers have to cope with slightly different operating principles depending on which part of the network they're on?

Thameslink does not have blue aspects.

For obvious reasons, ehen a train has an MA to a marker biard that is between two signals, the protecting signal will clear to Y, even though the full section to the next signal is not clear.

 

[St. Paddy]

Does The DMI give any routing information with the Movement Authority?

Despite a previous reply, yes it does give route indications. For example, entering Moorgate, you get a Route D or Route U for platform 9 or 10 respectively in the message box.
At other places, you would get a message with DS, UF etc

 

[stuu]

Isn't it only the Underground that uses blue aspects, to show ATO is in operation?

 

[Wapps]

Only in the sense that it's one step towards addressing one of the preconditions.

There are still, for example, a lot of level crossings on some sections.

What happens at a level crossing if a train goes through at 15mph faster?

 

[najaB]

What happens at a level crossing if a train goes through at 15mph faster?

Literal answer: The energy involved in a collision increase with the square of velocity, so a given collision at 140mph has something like 23% more energy compared to the same collision at 125mph.
Less literal answer: One of the regulatory requirements for railways with a line speed greater than 125mph is no level crossings.

 

[Class 800]

Literal answer: The energy involved in a collision increase with the square of velocity, so a given collision at 140mph has something like 23% more energy compared to the same collision at 125mph.
Less literal answer: One of the regulatory requirements for railways with a line speed greater than 125mph is no level crossings.

Is that achievable on the ECML? It feels like something that would cost a lot.
But at the risk of being a little blunt here, it's not like anyone would survive getting hit at 140 any more than they would survive getting hit at 125.

So perhaps it is worth finding a middle ground for some crossings where closure is not possible, ie having only level crossings with automatic full barriers or foot crossing gates that lock magnetically?

 

[najaB]

Is that achievable on the ECML? It feels like something that would cost a lot.

Now you're getting why we don't have 140mph running!

But at the risk of being a little blunt here, it's not like anyone would survive getting hit at 140 any more than they would survive getting hit at 125.

It's as much about the occupants of the train as it is about the crossing users. Moreso, actually.

So perhaps it is worth finding a middle ground for some crossings where closure is not possible, ie having only level crossings with automatic full barriers or foot crossing gates that lock magnetically?

Foot crossings are definitely out. The cost of building a foot bridge isn't going to be prohibitive (especially the new modular ones) and it will be significantly safer than a crossing that has to interact with the signalling system.

 

[Wapps]

Literal answer: The energy involved in a collision increase with the square of velocity, so a given collision at 140mph has something like 23% more energy compared to the same collision at 125mph.
Less literal answer: One of the regulatory requirements for railways with a line speed greater than 125mph is no level crossings.

Got it. What about the difference between 110 vs 125? 90 vs 125mph?

My concern is that we are ruling out improvements for the sake of a tiny theoretical risk. How often do we have trains at 125mph crashing at level crossings?

 

[Krokodil]

But at the risk of being a little blunt here, it's not like anyone would survive getting hit at 140 any more than they would survive getting hit at 125.

It's less about the impact speed and more about the warning time. In the UK 125mph is considered the limit of which a driver can rely on seeing signals etc. Not that a train can stop on sight from 125 but at least you can slow down considerably. Other countries are stricter and consider 200kph (125mph) to require cab signalling.

My concern is that we are ruling out improvements for the sake of a tiny theoretical risk. How often do we have trains at 125mph crashing at level crossings?

Once is enough. The HST at Ufton Nervet was only doing 98mph when the driver applied the emergency brake. He was killed, as well as five passengers. Level crossing risk should only be heading in one direction.

 

[Class 800]

Got it. What about the difference between 110 vs 125? 90 vs 125mph?

My concern is that we are ruling out improvements for the sake of a tiny theoretical risk. How often do we have trains at 125mph crashing at level crossings?

My question exactly.

Now you're getting why we don't have 140mph running!

It's as much about the occupants of the train as it is about the crossing users. Moreso, actually.
Foot crossings are definitely out. The cost of building a foot bridge isn't going to be prohibitive (especially the new modular ones) and it will be significantly safer than a crossing that has to interact with the signalling system.

But road crossings are the only places where the train risks impacting something heavy enough to significantly damage or derail it. And most of those crossings are equipped with lights / barriers anyway.

There is also the question of OLE, which we know is flimsy on the ECML.

In an ideal world we’d upgrade to the Series 1 OLE as newly installed on the GWML which is 140 rated.

 

[Wapps]

It's less about the impact speed and more about the warning time. In the UK 125mph is considered the limit of which a driver can rely on seeing signals etc. Not that a train can stop on sight from 125 but at least you can slow down considerably. Other countries are stricter and consider 200kph (125mph) to require cab signalling.


Once is enough. The HST at Ufton Nervet was only doing 98mph when the driver applied the emergency brake. He was killed, as well as five passengers. Level crossing risk should only be heading in one direction.

If the data from the UK shows that 125mph is safe without in cab signalling, that decision (of other countries) seems irrational.

 

[starlight73]

Isn't it only the Underground that uses blue aspects, to show ATO is in operation?

The Metropolitan & District lines have blue signals where trains enter an ATO area - I think no other London Underground lines use blue signals at present. MTR uses it abroad for ATO as well (source: here). But I think nowhere else in the UK, as you said

 

[najaB]

But road crossings are the only places where the train risks impacting something heavy enough to significantly damage or derail it.

Not entirely true - someone intent on derailing a train could do by putting something across the rails at a foot crossing. But the risk of that is low enough as can be ignored.

And most of those crossings are equipped with lights / barriers anyway.

Part of the problem is that as train speed increases, so does the time that the crossing has to be closed to road traffic. At some points on the southern ECML that could result in the crossings being closed far more than they are open.

In an ideal world we’d upgrade to the Series 1 OLE as newly installed on the GWML which is 140 rated.

The OHLE upgrade is already in progress. In several locations the headspans are being replaced by portals.

 

[Krokodil]

But road crossings are the only places where the train risks impacting something heavy enough to significantly damage or derail it. And most of those crossings are equipped with lights / barriers anyway.

Other than cement mixers, the vehicles that would do the most damage are tractors. They often use occupation crossings.

 

[Bald Rick]

But road crossings are the only places where the train risks impacting something heavy enough to significantly damage or derail it. And most of those crossings are equipped with lights / barriers anyway.

The trouble is that every single day, lights / barriers at level crossings are ignored (wilfully or accidentally) by road users somewhere in the country.

 

[DelW]

But road crossings are the only places where the train risks impacting something heavy enough to significantly damage or derail it. And most of those crossings are equipped with lights / barriers anyway.

Not so, even bridges don't entirely eliminate the risk, Great Heck and Oxshott being two recent(ish) examples. They are somewhat rarer though.