ETCS and Capacity increases

[Bartsimho]

I recently was poking around how to increase capacity and interoperability on European railways and saw that ETCS L2 can increase capacity: https://www.sciencedirect.com/science/article/pii/S2210970622000245
From this should be be looking for any line upgrades to include ETCS L2 capability. This would particularly help for the Timetablers as they would have more paths to play with.

(Also would this be a more cost-efficient capacity upgrade than the no-risk contracts they gave out)

 

[edwin_m]

The capacity benefit of Level 2 is fairly small. Having smaller blocks may help in some cases (where the equivalent conventional signalling would need more than 4 aspects or compromise maximum speeds). It may be possible to locate block markers optimally, where a signal couldn't be positioned due to sighting issues (but you'd still want to avoid tunnels and viaducts). On four-track routes the "slow line" block markers can be optimised to the braking of the train rather than having to be adjacent to the fast line ones as with signals.

Even Level 3 doesn't offer a huge capacity benefit, especially on routes where there is a mix of fast and slow or stopping and non-stop trains on the same track. The differences in average speed between these trains is usually the dominant factor limiting capacity.

 

[zwk500]

From this should be be looking for any line upgrades to include ETCS L2 capability.

NR intends to eventually upgrade nearly every line to ETCS L2.

This would particularly help for the Timetablers as they would have more paths to play with.

Yes and no. It has certain benefits but has zero impact on other problems.

(Also would this be a more cost-efficient capacity upgrade than the no-risk contracts they gave out)

Which no-risk contracts deliver more capacity?

The primary benefits from Level 2 are that you can have blocks as short as you need for any given headway, because they are no longer strictly tied to braking distances. It also allows the abolition of approach control, because the ATP function does that for you in a more efficient manner. However to have short blocks means increasing the interlocking complexity slightly.
However Level 2 does not fundamentally remove the constraints that stopping patterns, PSRs, speed differentials or different braking/acceleration capabilities impose, nor does it allow trains to get ahead of each other without additional track.
Level 2 in and of itself will not make lines faster, nor allow people to board/alight on the move, nor accelerate or brake faster (in fact braking curves may be lower because of the ATP factor).

So areas where L2 will give real capacity benefits are focused around Loops, Junctions and areas with trains at consecutive minimum headways on the same stopping patterns (e.g. major terminal approaches) already. Much of the network will largely not see any specific capacity upgrade from ETCS L2.

The main benefits of ETCS L2 to NR are the abolition of lineside signals, which removes a major risk of failure point, allows the simplification of lineside structures as Signal sighting becomes (almost) irrelevant, allows the elimination of any sighting-related restrictions, and allows a major cost in the design and approvals process to be massively simplified.

 

[Bartsimho]

Which no-risk contracts deliver more capacity?

This was a reference to the contracts given out for HS2 work as from as far as I'm aware they were with no risk to the contractors so the costs ballooned. From what I can see it was about capacity not speed as people are more likely to accept a slower turn up and go system than a faster wait a bit (within reason).

Did the implementation of ETCS on the ECML around Welwyn improve the capacity of that section which is just double track?

 

[zwk500]

This was a reference to the contracts given out for HS2 work as from as far as I'm aware they were with no risk to the contractors so the costs ballooned. From what I can see it was about capacity not speed as people are more likely to accept a slower turn up and go system than a faster wait a bit (within reason).

I think you are leaping ahead of yourself slightly. Building Hs2 is about capacity, but the contracts to build HS2 could have been done in many ways and you can't really say that these specific contracts represent the onyl other approach to capacity increases. Most construction contracts have late handover penalties.

Did the implementation of ETCS on the ECML around Welwyn improve the capacity of that section which is just double track?

ETCS isn't in at Welwyn yet. But It is projected that the installation of ETCS L2 will add the equivalent capacity that 4-tracking that section would have done. However Digswell Viaduct/Welwyn North is a very specific area because of the Proximity of Welwyn GC, Digswell Jn, Welwyn North and Woolmer Green Jn. This is one area where the elimination of approach control and short block length is a capacity benefit.
However further north, e.g. from Peterborough to Stoke Jn the spec for ETCS there is likely to be much the same as the current signalling achieves, because it isn't worth spending the money to squeeze the extra capacity out.

 

[snowball]

Marke Carne, CEO of Network Rail 2013-2018 (and not to be confused with Mark Carney, Governor of the Bank of England 2013-2020) was a great enthusiast for ETCS level 2 because he had swallowed some possibly over-optimistic projections of the capacity improvements it could provide. Maybe he also overestimated the ease of introducing it - five years after he left and we are only just now getting its introduction on a multiple-track line.

As an example of a body less enthusiastic, there's the Scottish government. The recently published Scotland HLOS says

The Scottish Ministers have considered carefully the planned approach to signalling investment elsewhere in Great Britain for CP7, but consider that it does not align with Scotland’s strategic priorities at this time.

In particular, the Scottish Ministers consider that no business case exists for the European Train Control System (ETCS) Level 2 in Scotland at this time, as the railway traffic characteristics and capacity issues are not the same as those for which this system is more effective. Further, that the potential benefits of this system may be secured more cost effectively, more quickly and at lower risk by other investments.

 

[zwk500]

Marke Carne, CEO of Network Rail 2013-2018 (and not to be confused with Mark Carney, Governor of the Bank of England 2013-2020) was a great enthusiast for ETCS level 2 because he had swallowed some possibly over-optimistic projections of the capacity improvements it could provide. Maybe he also overestimated the ease of introducing it - five years after he left and we are only just now getting its introduction on a multiple-track line.

BIB: Very definitely - although it should be noted that the technology has matured significantly in the last 3-5 years as it's rollout accelerates in Europe. The UK was heavily involved in the testing regime for it but deployment has been slowed by the amount of background work required. Resignalling and resurveying are costly endeavours, whereas a lot of Europe was already able to build on existing ATP systems for L1 rollout which has aided L2 installations.

Part of the problem was the GW modernisation, which raised concerns about major capital projects like ETCS rollout and also the rapid explosion in passenger numbers necessitated interventions that could be delivered quickly, before COVID then caused all sorts of other problems.

As an example of a body less enthusiastic, there's the Scottish government. The recently published Scotland HLOS says

Funnily enough, I would think that the Scottish central belt network is actually perfect for ETCS L2. But north of Stirling and Dundee the benefits start to drop off considerably.

 

[HSTEd]

As an example of a body less enthusiastic, there's the Scottish government. The recently published Scotland HLOS says

I wonder whether the costings for any of these "lower risk" investments have been properly costed, given that every rail project seems to run hugely over budget these days!

The reality is that whether or not there is a "business case" for installation, the choice is either to have a slowly disintegrating signalling system (because the industrial capacity to keep it in good condition long term simply does not exist) or adopt ETCS.

The status quo is not sustainable and thus a "do nothing" solution is not feasible, as much as various railway managers would love it to be. The bullet has to be bitten

 

[paul1609]

BIB: Very definitely - although it should be noted that the technology has matured significantly in the last 3-5 years as it's rollout accelerates in Europe. The UK was heavily involved in the testing regime for it but deployment has been slowed by the amount of background work required. Resignalling and resurveying are costly endeavours, whereas a lot of Europe was already able to build on existing ATP systems for L1 rollout which has aided L2 installations.

Part of the problem was the GW modernisation, which raised concerns about major capital projects like ETCS rollout and also the rapid explosion in passenger numbers necessitated interventions that could be delivered quickly, before COVID then caused all sorts of other problems.

Funnily enough, I would think that the Scottish central belt network is actually perfect for ETCS L2. But north of Stirling and Dundee the benefits start to drop off considerably.

Is Great Western Modernisation a new name for GWEP which overan budget by 500% when it was stopped partially completed 4 years behind time?

 

[plugwash]

Even Level 3 doesn't offer a huge capacity benefit, especially on routes where there is a mix of fast and slow or stopping and non-stop trains on the same track. The differences in average speed between these trains is usually the dominant factor limiting capacity.

What about the "platforms on loops" scenario? Where a station has platforms on loops so that the stopper can stop while the express goes through non-stop.

My understanding is that with conventional signalling this results in a very long dwell time for the stopper, how much can ETCS improve this?

 

[HSTEd]

Is Great Western Modernisation a new name for GWEP which overan budget by 500% when it was stopped partially completed 4 years behind time?

It is often referred to as the Great Western Route Modernisation by analogy with the similarly disasterous West Coast Route Modernisation of the early privatisation era. I have seen both GWEP and GWRM used in documents over the years.

 

[zwk500]

Is Great Western Modernisation a new name for GWEP which overan budget by 500% when it was stopped partially completed 4 years behind time?

Not 'new', just a different way of referring to it. See this 2011 PDF: https://web.archive.org/web/2013041...rovements/The_Great_Western/WesternVision.pdf

 

[The Planner]

What about the "platforms on loops" scenario? Where a station has platforms on loops so that the stopper can stop while the express goes through non-stop.

My understanding is that with conventional signalling this results in a very long dwell time for the stopper, how much can ETCS improve this?

Its not a simple answer as it depends on where block markers get placed. The headway and turnout speeds to the loops dictate the dwell time.

 

[edwin_m]

What about the "platforms on loops" scenario? Where a station has platforms on loops so that the stopper can stop while the express goes through non-stop.

My understanding is that with conventional signalling this results in a very long dwell time for the stopper, how much can ETCS improve this?

Its not a simple answer as it depends on where block markers get placed. The headway and turnout speeds to the loops dictate the dwell time.

There is the potential for the train to start from the loop as soon as the non-stop one has passed and the points have changed. But conventional 4-aspect signalling would allow that train to start on a single yellow within less than 30s anyway.

The train entering the loop has to be clear inside and the points switched before the non-stopping train arrives at the place where it would have to brake for the loop entry signal. If a conventional signal can be placed optimally for that scenario, then most of the train separation is down to the stopping distance of the non-stopping train, which doesn't depend on the type of signalling used. There might be a bit more benefit if the non-stopping trains had different stopping distances, as ETCS could vary the braking point accordingly, but most passenger trains are pretty uniform in that respect.

So the dwell time saving is usually pretty small.

 

[zwk500]

There is the potential for the train to start from the loop as soon as the non-stop one has passed and the points have changed. But conventional 4-aspect signalling would allow that train to start on a single yellow within less than 30s anyway.

The train entering the loop has to be clear inside and the points switched before the non-stopping train arrives at the place where it would have to brake for the loop entry signal. If a conventional signal can be placed optimally for that scenario, then most of the train separation is down to the stopping distance of the non-stopping train, which doesn't depend on the type of signalling used. There might be a bit more benefit if the non-stopping trains had different stopping distances, as ETCS could vary the braking point accordingly, but most passenger trains are pretty uniform in that respect.

So the dwell time saving is usually pretty small.

The key saving here will be the reduction in runtime allowed by eliminating approach control and using the normal braking curve (where turnout speed permits). But it also would rely on the following train being timed to get a full MA right up until the first train is clear inside and able to take the pass at full speed.
You'd be looking at a 1' reduction max in most places, maybe 2' in some.

 

[HSTEd]

There is the potential for the train to start from the loop as soon as the non-stop one has passed and the points have changed. But conventional 4-aspect signalling would allow that train to start on a single yellow within less than 30s anyway.

If the loop is a few hundred metres long beyond the platform signal then it can probably start rolling before the non-stop one has passed. It just has to be able to stop before the points as insurance against them failing to set in time.

 

[zwk500]

If the loop is a few hundred metres long beyond the platform signal then it can probably start rolling before the non-stop one has passed. It just has to be able to stop before the points as insurance against them failing to set in time.

The loop would have to be longer than a few hundred metres for it to be worth doing that. The benefit of having a second stop marker further on up the loop would be miniscule.

 

[lammergeier]

Forgive me for the slight thread drift, but how is routing dealt with and displayed to the driver in ETCS? I'm thinking especially for somewhere like Colton where the turnout speeds are the same no matter which direction you're going, or approaching complex stations where it's important you use a particular platform due to train/platform length, available routes etc. Are there still lineside signals at junctions or does the driver get an in cab indication as to which route is set?

 

[Railsigns]

Funnily enough, I would think that the Scottish central belt network is actually perfect for ETCS L2. But north of Stirling and Dundee the benefits start to drop off considerably.

It's currently envisaged that the first line in Scotland to get ETCS will be the Argyle Line, followed by the East Coast Main Line.

 

[The Planner]

There is the potential for the train to start from the loop as soon as the non-stop one has passed and the points have changed. But conventional 4-aspect signalling would allow that train to start on a single yellow within less than 30s anyway.

The train entering the loop has to be clear inside and the points switched before the non-stopping train arrives at the place where it would have to brake for the loop entry signal. If a conventional signal can be placed optimally for that scenario, then most of the train separation is down to the stopping distance of the non-stopping train, which doesn't depend on the type of signalling used. There might be a bit more benefit if the non-stopping trains had different stopping distances, as ETCS could vary the braking point accordingly, but most passenger trains are pretty uniform in that respect.

So the dwell time saving is usually pretty small.

That is the technical reality, planning it is different. You arent worrying about signal sighting so the markers will likely be in the places you state whereas a light on stick won't be.

 

[XAM2175]

Forgive me for the slight thread drift, but how is routing dealt with and displayed to the driver in ETCS? I'm thinking especially for somewhere like Colton where the turnout speeds are the same no matter which direction you're going, or approaching complex stations where it's important you use a particular platform due to train/platform length, available routes etc. Are there still lineside signals at junctions or does the driver get an in cab indication as to which route is set?

There is (to the best of my knowledge) provision in the ETCS standard for it be displayed to the driver in a "planning" window on the DMI.

 

[HSTEd]

Forgive me for the slight thread drift, but how is routing dealt with and displayed to the driver in ETCS? I'm thinking especially for somewhere like Colton where the turnout speeds are the same no matter which direction you're going, or approaching complex stations where it's important you use a particular platform due to train/platform length, available routes etc. Are there still lineside signals at junctions or does the driver get an in cab indication as to which route is set?

Ultimately ETCS Is a true speed signaling system, which means that it is not strictly necessary for the driver to know what route is set.
In theory, the driver can drive the train safely with no route knowledge by simply driving to the gauges (I am not actually suggesting that this is a good idea).

I believe some functionality is provided to allow additional information to be displayed, but these systems ultimately depend on ensuring that the wrong route doesn't get set in the first place.
Given that the signaling system knows, definitively, the identity of every train, in theory, the risk of setting wrong routes should be substantially reduced.

 

[lammergeier]

Ultimately ETCS Is a true speed signaling system, which means that it is not strictly necessary for the driver to know what route is set.
In theory, the driver can drive the train safely with no route knowledge by simply driving to the gauges (I am not actually suggesting that this is a good idea).

I believe some functionality is provided to allow additional information to be displayed, but these systems ultimately depend on ensuring that the wrong route doesn't get set in the first place.
Given that the signaling system knows, definitively, the identity of every train, in theory, the risk of setting wrong routes should be substantially reduced.

I sort of thought that was the case, but just wondered if there was a last line of defence. Was thinking about it after being wrong routed for the third time this year recently.