Elizabeth Line - total loss of signalling 26/11

[PudseyBearHST]

I’m not an expert at all… I believe the difference is:

ETCS is a standard system - different manufacturers make their own ETCS equipment. But in theory, it should behave in a similar way to other ETCS systems and it should be able to work with other ETCS equipment from different manufacturers.

CBTC is a generic term that means Communications Based Train Control. It means that there’s some kind of computerised system that drives and signals trains, and it sends signals over specialised radio or Wi-Fi signals (note that some forms of ETCS do use radio signals and ETCS can also drive trains)

There are different varieties of CBTC from different manufacturers. For example, Siemens CBTC (Elizabeth line) and Thalys CBTC (Circle, District, Ham & City, Metropolitan lines). However, these are all proprietary systems and cannot communicate with each-other.

So a very inaccurate analogy could be: ETCS is a common standard, a bit like email (you can send an email from Gmail to Outlook to Yahoo mail, and it will basically look and do the same thing, with small differences). And CBTC is a bit like a specific messaging platform that can only communicate with itself (Facebook messenger, Telegram, etc.). Of course, there’s a ton of differences between email and train signalling

now to hear about everything that’s inaccurate in this post,,, in a separate thread maybe - sorry this should probably move into a separate thread mods!!

ETCS is the European Train Control System. It is used on the Line to Heathrow in a mode called Level 2 where it has fixed signalling blocks and lineside signals are not needed. Trains are given movement authority to the end of a block. It uses an in-cab display to tell the driver when to stop and how far and how fast to drive to the next stop. The onboard systems communicate with a central signalling centre via the radio system which is based on GSM mobile phone technology.

The Trainguard CBTC system used in the Crossrail Core is a moving block signalling system where each train gets movement authorities up to the back of the train in front (with a small safety margin) and uses the same ETCS display to tell the driver what to do but can also operate with Automatic Train Control where the train is driven by the onboard computer. It operates as a subsystem of ETCS where a module can be plugged in to run the Trainguard CBTC software. It communicates with the central signalling centre via a wi-fi like system which can handle higher traffic rates so movement authority is updated more often and the number of trains per hour can be much higher.

Both of the above use Eurobalises in the four foot to pass position information to train so that it knows where it is.

The ETCS system on the Elizabeth Line Trains also has a plug-in module for handling the more common TPWS signalling used on the GWML and GEML and most other UK network rail lines.
The main difference between the switchovers between signalling at each side is that on the GWML the switchover on the GWML is done while moving while the one on the GEML is done while stationary at the platform at Stratford.

I hope that helps.

Fantastic, thanks for the responses.

With regards to the “moving block system,” I notice the Crossrail core has ERTMS boards which act like signals and where you stop? How does this work if it’s moving block? I don’t have a lot of knowledge of in cab signalling. Thanks

 

[Harpo]

ETCS can mimic moving block with short block sections, a bit like LNER did on the Shenfield line with multiple 2Y aspects close together.

The advantage of ETCS over colour lights for short block sections is that it has no direct impact on line speed.

 

[kevin_roche]

With regards to the “moving block system,” I notice the Crossrail core has ERTMS boards which act like signals and where you stop? How does this work if it’s moving block? I don’t have a lot of knowledge of in cab signalling. Thanks

I think ETCS with manual driving or CBTC can be used as a backup with manual driving when ATO fails. The boards are needed when the train is being driven manually.

 

[PudseyBearHST]

I think ETCS with manual driving or CBTC can be used as a backup with manual driving when ATO fails. The boards are needed when the train is being driven manually.

Interesting thanks for the response

 

[LYuen]

I think it was a case of politics interfering with Engineering.

Crossrail limited made it quite clear to Boris and TFL that the sensible procurement option would be trains compatible with the Siemens CBTC signalling system. At the time the decision was made to use CBTC it was being installed in, I think Hong Kong, so would be a tested and proven system before being used on Crossrail.

But Boris was on a crusade to wave the flag and buy British. Hence the mismatch.

Hong Kong first adopted Thales SelTrac CBTC signalling for KCR West Rail Line in 2003, a really bold move back then. I think it is the very first SelTrac CBTC application in heavy mainline rail.
Since then this signalling system has become quite proven and reliable, and was adopted by Tube lines as well.

Hong Kong did have Sieman's Trainguard MT CBTC on the East Rail line, but it was only commissioned in 2021.
In hindsight SelTrac might be better fit for Crossrail than Trainguard, 1. It is proven and used by the Tube lines too. 2. Alstom and Thales have been collaborating, which should avoid the gap we have.

Seltrac has problem in Hong Kong too (including a crash), but it was discovered and fixed before commissioning.

 

[AndrewE]

UK underestimates threat of cyber-attacks from hostile states and gangs, says security chief

New head of National Cyber Security Centre to warn of risk to infrastructure in first major speech

www.theguardian.com

The UK is underestimating the severity of the online threat it faces from hostile states and criminal gangs, the country’s cybersecurity chief will warn.

Richard Horne, the head of GCHQ’s National Cyber Security Centre, will cite a trebling of “severe” incidents amid Russian “aggression and recklessness” and China’s “highly sophisticated” digital operations.
In his first major speech as the agency’s chief, Horne will say on Tuesday that hostile activity in UK cyberspace has increased in “frequency, sophistication and intensity” from enemies who want to cause maximum disruption and destruction.

so are the pople wondering what caused the LizLine signalling failures still wild conspiracy theorists, or is it possible it really was wrecked from outside?

 

[Horizon22]

so are the pople wondering what caused the LizLine signalling failures still wild conspiracy theorists, or is it possible it really was wrecked from outside?

It wasn't.

 

[AndrewE]

It wasn't.

I shall take that as an authoritative response from an infromed source then!

Admittedly we were told [here] that it was "just software that went wrong" but really?
If something as important as our capital's public transport infrastructure is that ineptly managed, then how do we manage our way out of this trough of incompetence?

 

[boiledbeans2]

No trains in the central section right now (29th Jan) due to issues with the signalling system according to TfL status.

Is it the same issue as that of 26th Nov?

Not been a good week for the Elizabeth line. Yesterday (28th Jan), there was a power failure in the Paddington area, with no trains in the western section.

 

[Watershed]

No trains in the central section right now (29th Jan) due to issues with the signalling system according to TfL status.

Is it the same issue as that of 26th Nov?

Not been a good week for the Elizabeth line. Yesterday (28th Jan), there was a power failure in the Paddington area, with no trains in the western section.

Also issues on Sunday and (IIRC) Monday. This morning there was also a track fault at Acton meaning both peaks were write-offs.

TfL doesn't exactly do much for the outer surburban stations when disruption happens. "Tickets will be accepted on London buses" - not much use if you're travelling from the likes of Iver or Langley, let alone Maidenhead or Twyford...

 

[ChrisHogan]

No trains in the central section right now (29th Jan) due to issues with the signalling system according to TfL status.

Is it the same issue as that of 26th Nov?

Not been a good week for the Elizabeth line. Yesterday (28th Jan), there was a power failure in the Paddington area, with no trains in the western section.

And disruption on Tuesday due to an object on the overheads in the Acton area. GWR seems to be much better than MTR at restoring a credible service after these infrastructure problems.

 

[crablab]

TfL doesn't exactly do much for the outer surburban stations when disruption happens. "Tickets will be accepted on London buses" - not much use if you're travelling from the likes of Iver or Langley, let alone Maidenhead or Twyford...

Since it's NRCoT, wonder if any of these passengers have been requesting taxis or other alternative arrangements be made?

 

[GraphitProjekt]

Not been a good week for the Elizabeth line. Yesterday (28th Jan), there was a power failure in the Paddington area, with no trains in the western section.

Yeah it is quite precarious running the whole of the GWML east of Maidenhead on one grid supply at Kensal Rise

 

[Watershed]

Since it's NRCoT, wonder if any of these passengers have been requesting taxis or other alternative arrangements be made?

TfL certainly doesn't make it easy to claim those costs back. I've never had an experience with their customer services where I have felt the person on the other end actually understood what I was saying.

 

[800301]

No trains in the central section right now (29th Jan) due to issues with the signalling system according to TfL status.

Is it the same issue as that of 26th Nov?

Not been a good week for the Elizabeth line. Yesterday (28th Jan), there was a power failure in the Paddington area, with no trains in the western section.

Axle counter/detection failure at Whitechapel, now resolved

 

[Dave W]

Also issues on Sunday and (IIRC) Monday. This morning there was also a track fault at Acton meaning both peaks were write-offs.

And was stuffed Saturday lunchtime too, as my precariously holding on to a pram (empty; wife in charge of baby) down the Central Line escalator at Liv St will attest.

Worrying run of reliability.

 

[iphone76]

It's certainly a challenging period. Today marks the 6th consequitive day of major disruption. In addition to the above, on Friday there were major issues with the fallen tree between Brentwood and Shenfield and issues with the tunnel ventilation system on Saturday.

Matters aren't helped with the current lack of a driver RDW agreement (since 28th Dec last year). This means quite a few jobs are uncovered each day. All cover and most standby jobs are now cancelled. Those drivers revert to spare but are then typically reassigned other jobs and aren't available to help get the service back to normal. Diagrams are now also quite tight with minimum 'stepback' times, and changing drivers en route at Paddington and Gidea Park so once it all falls apart, it's a nightmare to piece it all back together.

You may also see a few trains each day now pre-cancelled each day at 22.00 and then more cancelled during the day due to a shortage of train crew. Quite a few of these shortages are now masked with these recent issues. Early in the New Year quite a few first and last trains between Liverpool Street and Shenfield were cancelled. This would have been unthinkable until recently.

Let's hope this is resolved soon.

 

[DerekC]

The decision on the Crossrail signalling system was taken at a time when ETCS did not have an ATO product, nor couldd interface with screen doors, nor could it tackle auto reverse, which was a requirement. ETCS still does not have the latter two, and only gained the ATO product properly very recently.

Yes and no. ATO over ETCS used in the TL core is actually a Siemens bespoke product, and has limited capacity, hence why it runs only for about 8km. I have heard it is not extendable on Thameslink for that reason (unfortunately) but would be delighted to be proved wrong. However if this is the case, then there would not have been capacity for the same system to be used for Crossrail which is more than 3 times longer.

A significant effort was made to get Crossrail to work with Thameslink on procuring a common ETCS-based ATO system for both, but TfL was adamant that it wanted a London Underground style CBTC for Crossrail and refused to consider ETCS. The advantage of using an ETCS base would have been to have a common system for the Crossrail core and GWML, making the interface at the end just a question of cutting ATO in and out. I can see no reason why the Thameslink ATO system couldn't have handled the Crossrail core length - the amount of extra data to be held is pretty small by modern standards. I don't think there is any fundamental reason why auto reverse couldn't have been developed, and the stopping accuracy requirements for Thameslink are close to those for PSD anyway.

 

[Thirteen]

I bet they'll be some here, elsewhere and in the media proclaiming the Elizabeth Line to be a failure because of these issues!

 

[boiledbeans2]

[...]

Matters aren't helped with the current lack of a driver RDW agreement (since 28th Dec last year). This means quite a few jobs are uncovered each day. All cover and most standby jobs are now cancelled. Those drivers revert to spare but are then typically reassigned other jobs and aren't available to help get the service back to normal. Diagrams are now also quite tight with minimum 'stepback' times, and changing drivers en route at Paddington and Gidea Park so once it all falls apart, it's a nightmare to piece it all back together.

You may also see a few trains each day now pre-cancelled each day at 22.00 and then more cancelled during the day due to a shortage of train crew. Quite a few of these shortages are now masked with these recent issues. Early in the New Year quite a few first and last trains between Liverpool Street and Shenfield were cancelled. This would have been unthinkable until recently.

Let's hope this is resolved soon.

MTR no longer care as they only have 4 months to go?

 

[Horizon22]

MTR no longer care as they only have 4 months to go?

That’s certainly one argument although you would think TfL might considering it’s their branding everywhere and they are the public image of the line no matter who runs the concession.

 

[Purple Train]

TfL certainly doesn't make it easy to claim those costs back. I've never had an experience with their customer services where I have felt the person on the other end actually understood what I was saying.

Getting money from TfL is like getting blood from a stone. Monday and Tuesday are the only two days when I've had to abandon my journey and get a lift, even including the original disruption this thread was about. Tuesday in particular was complete carnage in the morning. Hopefully it's just a blip as it's been very reliable out west these last couple of months or so.

 

[DoubleLemon]

A significant effort was made to get Crossrail to work with Thameslink on procuring a common ETCS-based ATO system for both, but TfL was adamant that it wanted a London Underground style CBTC for Crossrail and refused to consider ETCS. The advantage of using an ETCS base would have been to have a common system for the Crossrail core and GWML, making the interface at the end just a question of cutting ATO in and out. I can see no reason why the Thameslink ATO system couldn't have handled the Crossrail core length - the amount of extra data to be held is pretty small by modern standards. I don't think there is any fundamental reason why auto reverse couldn't have been developed, and the stopping accuracy requirements for Thameslink are close to those for PSD anyway.

I read somewhere the reason was ECTS was consider not mature enough to work with the platform screen doors accurately every time when the decisions were being made.

 

[Taunton]

Strange. The Russian Metros in Moscow and St Petersburg have had edge doors since the 1970s. They are a bit different as they are not glazed, so the platform is just like a passage with a series of lift doors, but the stopping accuracy needed for doors to coincide is the same. Video here:

Then when the Jubilee Line opened the stopping precision was achieved by manual driving, which I found worked perfectly. However could ETCS not achieve the same? They have become quite common on Metros worldwide.

 

[Backroom_boy]

Yes if they made the decision at the time it opened it would have been an easy option to go with ETCS, but it the decision was made years previously where ETCS developments could only be anticipated. Was it the wrong signally option? probably. But without hindsight it would have have been a brave decision to go with ETCS

 

[Harpo]

Was it the wrong signally option? probably. But without hindsight it would have have been a brave decision to go with ETCS

I doubt that TfL regrets keeping everyone else's tanks off of their lawn with a customised system in the core.

 

[tom1649]

That’s certainly one argument although you would think TfL might considering it’s their branding everywhere and they are the public image of the line no matter who runs the concession.

Could TfL take the operation in house, or is it obliged to put it out to tender?

 

[Vexed]

I doubt that TfL regrets keeping everyone else's tanks off of their lawn with a customised system in the core.

The infrastructure is owned by TfL's Rail for London (Infrastructure) Limited, not Network Rail. So they have quite a lot of control regardless of signalling incompatibility.

 

[Harpo]

The infrastructure is owned by TfL's Rail for London (Infrastructure) Limited, not Network Rail. So they have quite a lot of control regardless of signalling incompatibility.

Not disputed. But that’s only a control that current legislation gives them.

 

[Bald Rick]

Strange. The Russian Metros in Moscow and St Petersburg have had edge doors since the 1970s. They are a bit different as they are not glazed, so the platform is just like a passage with a series of lift doors, but the stopping accuracy needed for doors to coincide is the same. Video here:

Then when the Jubilee Line opened the stopping precision was achieved by manual driving, which I found worked perfectly. However could ETCS not achieve the same? They have become quite common on Metros worldwide.

It wasn’t about stopping the train in the right place. It was simlly that ETCS did not have the relevant safety critical software modules that enabled the train to ‘talk‘ to the doors.

But it wasn’t just that, as I said in my post (a long way) upthread.

There was an unoffical competition to see whether Thameslink (ATO over ETCS) or Crossrail (ATO over CBTC) would have the ATO in passenger service first. Thameslink won at a canter. Albeit Crossrail finished first!