Questions regarding timetabling, pathing and track capacity into London Paddington

[kevin_roche]

Moderator note: Split from

Crossrail opening delayed (opening date not yet known)

Crossrail was a hands off project. Both its equal cosponsors thought it was a good idea at the time. Not sure what hand the then Mayor had in it, but I’m sure the person with the current purse strings could offer some explanation with the further bailout.

www.railforums.co.uk

A question about timetables and track capacity.

The current TfL Rail West timetable published on the TfL website, which I assume was developed before the Covid crisis, has a minimum separation between trains arriving at Paddington in the morning peak of 6 minutes.

I'm just wondering what the constraints were that made that decision.

The future plans for Elizabeth line service will need the separation to be 5 minutes to get 12 tph.

Is the only capacity constraint the lines into the station or are there others? Is the current TPWS/AWS signalling a constraint? If so, will it be fixed by the ETCS overlay that is being installed? I can't see how myself but maybe there are other changes being made too.

My thoughts were triggered by a couple of things. One was some suggested changes when Old Oak Common opens that more trains could continue to OOC and turn there instead of on the current turnbacks and the other being the possible plan for a North Kensington Station.

Is there line capacity on the Relief Line between the Westbourne Park Portal and OOC to allow more than 12tph? Would there have to be track changes to allow it? Is anything like that planned already for the HS2 OOC station build?

Kevin

 

[Horizon22]

A question about timetables and track capacity.

The current TfL Rail West timetable published on the TfL website, which I assume was developed before the Covid crisis, has a minimum separation between trains arriving at Paddington in the morning peak of 6 minutes.

I'm just wondering what the constraints were that made that decision.

The future plans for Elizabeth line service will need the separation to be 5 minutes to get 12 tph.

Is the only capacity constraint the lines into the station or are there others? Is the current TPWS/AWS signalling a constraint? If so, will it be fixed by the ETCS overlay that is being installed? I can't see how myself but maybe there are other changes being made too.

My thoughts were triggered by a couple of things. One was some suggested changes when Old Oak Common opens that more trains could continue to OOC and turn there instead of on the current turnbacks and the other being the possible plan for a North Kensington Station.

Is there line capacity on the Relief Line between the Westbourne Park Portal and OOC to allow more than 12tph? Would there have to be track changes to allow it? Is anything like that planned already for the HS2 OOC station build?

Kevin

Conflicts with the Paddington arrival / departures I would imagine. There are still several GWR services around the higher platforms that TfL tend to use and can conflict there. Not sure what the intention is for the GWR Didcot Parkway stoppers when Crossrail is fully running but probably just a minor retiming. Signaling I imagine may be one constraint (we're talking about 1 minute headway to be shaved) as ETCS to Paddington isn't installed yet (and has no deadline to be...). The section from Airport Junction to Ealing Broadway is currently being worked on.

 

[SynthD]

Kevin you’re comparing TfL rail using parts of the main station with the future Elizabeth line using its own station below. They plan to increase the frequency later on so they’ve made the relief lines to old oak common capable of the full service - 11 car, 30tph.

 

[kevin_roche]

Kevin you’re comparing TfL rail using parts of the main station with the future Elizabeth line using its own station below. They plan to increase the frequency later on so they’ve made the relief lines to old oak common capable of the full service - 11 car, 30tph.

I am wondering how they have done that. Were extra signals added? Are the blocks on that stretch smaller? Does any of that depend on completion of the ETCS overlay?

 

[31160]

Sorry if im being stupid, but will there be any predictable passenger use for the new dive under at acton or is for after Crossrail opens

 

[hwl]

I am wondering how they have done that. Were extra signals added? Are the blocks on that stretch smaller? Does any of that depend on completion of the ETCS overlay?

The current capacity is limited by the number of (high level) platforms available to relief line trains and the trackwork in the station throat.
12tph is easily achievable as soon as the platform and throat issues are removed i.e. the trains just move to the new platforms downstairs.

24tph to OOC etc needs the new station at OOC (as there are capacity limits west of there hence high capacity turnback) and ETCS etc.

Sorry if im being stupid, but will there be any predictable passenger use for the new dive under at acton or is for after Crossrail opens

It is for removing freight /passenger conflicts hence only certain (mainly ex Heathrow? which will increase from 2 to 6tph in the future) services might use it.

 

[Horizon22]

Sorry if im being stupid, but will there be any predictable passenger use for the new dive under at acton or is for after Crossrail opens

Yes the dive-under is used (often adhoc) depending on freight conflicts out of the busy Acton Yard and I imagine will continue to be used.

 

[WindsorJoe]

My train this morning the 07.54 from slough to Paddington used the dive under, was the first time I've been on a train that's used it.

 

[Taunton]

Why is the Acton Up Relief diveunder not used all the time; one would have thought there would be some corporate memory on this line seeking to keep Up passenger services away from Down crossing freights at all times where possible, and not just rely on signals ...

 

[Starmill]

Why is the Acton Up Relief diveunder not used all the time; one would have thought there would be some corporate memory on this line seeking to keep Up passenger services away from Down crossing freights at all times where possible, and not just rely on signals ...

As a safety critical system, I'd be disappointed if it were felt that the signalling couldn't be relied upon, for any reason.

 

[kevin_roche]

Why is the Acton Up Relief diveunder not used all the time; one would have thought there would be some corporate memory on this line seeking to keep Up passenger services away from Down crossing freights at all times where possible, and not just rely on signals ...

The advantage of TPWS and the soon to be installed ETCS L2 is that you are not relying on the driver seeing a signal. The train brakes will be applied if the driver passes a red signal. There are also interlocks which set signals and points together so setting a route that a freight service can take will automatically make appropriate changes to signals and stop conflicting changes to other points.

 

[Taunton]

The advantage of TPWS and the soon to be installed ETCS L2 is that you are not relying on the driver seeing a signal.

My reference was to two of the most serious high-fatality collisions of the past generation, including one where exactly an up passenger service struck a down freight crossing over, happened right here despite ATP being installed on this very line at the time. Both involved a passenger service barrelling through a red at speed and the ATP (supposedly more advanced that TPWS) not catching it.

 

[norbitonflyer]

My reference was to two of the most serious high-fatality collisions of the past generation, including one where exactly an up passenger service struck a down freight crossing over, happened right here despite ATP being installed on this very line at the time. Both involved a passenger service barrelling through a red at speed and the ATP (supposedly more advanced that TPWS) not catching it.

It didn't catch it because ATP was not in operation on either SPADding train (and in one case nor was AWS)

Since the diveunder opened I have been through it on 100% of the trains using the up relief on which I have travelled. (One train)

 

[cactustwirly]

Why is the Acton Up Relief diveunder not used all the time; one would have thought there would be some corporate memory on this line seeking to keep Up passenger services away from Down crossing freights at all times where possible, and not just rely on signals ...

The diveunder is used by a fair amount of services tbf

 

[Ianno87]

Why is the Acton Up Relief diveunder not used all the time; one would have thought there would be some corporate memory on this line seeking to keep Up passenger services away from Down crossing freights at all times where possible, and not just rely on signals ...

I believe the flat route is fractionally shorter and quicker. So if there's no conflicting freight, better to send an Up Relief passenger service straight on rather than through the dive under.

Also saves wear on the points by minimising the number of "Reverse" moves through them.

 

[Horizon22]

My reference was to two of the most serious high-fatality collisions of the past generation, including one where exactly an up passenger service struck a down freight crossing over, happened right here despite ATP being installed on this very line at the time. Both involved a passenger service barrelling through a red at speed and the ATP (supposedly more advanced that TPWS) not catching it.

The ATP wasn't switched on the HST at Southall (wasn't compulsory and driver hadn't been trained) AND the AWS had been isolated. You wouldn't even contemplate running that train today.

It's mixed as to whether trains use the dive-under or not, depends what state the ARS is in I imagine. If no freight is diagrammed for hours in or out of the yard, and there's no need to switch the points why would the signaller?

 

[Taunton]

The ATP wasn't switched on the HST at Southall (wasn't compulsory and driver hadn't been trained) AND the AWS had been isolated. You wouldn't even contemplate running that train today.

Well that's true of most accidents, that "X should have been done". Ladbroke Grove had no flank protection diverting an overrunning Down train onto the Down Relief, letting it just run head-on into the Up Main, because the signal designers thought it not necessary, as everything had ATP. Here we have a conflict-free (and expensive) line not being used much of the time.

 

[Starmill]

This reminds me of the argument that freight should always use the York avoiding lines and never pass through the station, despite it being slower, just in case a passenger leaps from the platform onto a wagon. The only justification in both cases appears to be that the infrastructure just so happens happens to be in place.

Of course, there's no suggestion that every East Coast Main Line station should have freight avoiding lines constructed. Or that every Great Western Main Line crossing should be grade separated.

 

[Nippy]

Regarding the Acton Dive-Under Line. Every passenger train booked Up Relief is timetabled to use it as the ARS preferred route. There is no separate line code so all trains will use it by default and indeed I would suggest that 99% of them do on weekdays. If, however a train is closely following one in the Dive-Under Line, ARS will select the straight route as it does keep things moving. To counter this, we normally have a Reminder on SN.192 on the Up Relief to force ARS to use the Dive-Under Line to ensure that the Freight route to the Down Relief/Main is never locked by trains on the Up Relief (The route would be set by ARS back at West Ealing, locking the junction for 5-6 minutes). We cannot route into the Dive-Under Line unless the signal is showing a proceed aspect to come out of it.

The Class 332s are not allowed through there and Class 800/2ss only relatively recently being route cleared means that if for any reason the Up Main is shut (for instance at weekends or late evening and overnight) we often run everything Up Relief and put the route into 'auto' to prevent one inadvertently being routed through there as there is no advance warning for drivers until it's too late.....

Reason for Edit: Adding more details

 

[Cricketer8for9]

Why are 332s not allowed through the dive under?

 

[Dren Ahmeti]

Why are 332s not allowed through the dive under?

Someone like @Nippy, @Clarence Yard or @JN114 might be able to advise, as I haven’t found anything in the sectional appendix that suggests that that is the case.

 

[JN114]

Why are 332s not allowed through the dive under?

They never have been - I don’t know exactly why though. Few platforms at Paddington they’re banned from as well.

 

[Ianno87]

They never have been - I don’t know exactly why though. Few platforms at Paddington they’re banned from as well.

It is 'Explicitly not permitted' or simply 'Have never been cleared to because the paperwork has never been done', if you see what I mean?

 

[JN114]

It is 'Explicitly not permitted' or simply 'Have never been cleared to because the paperwork has never been done', if you see what I mean?

It’s in our desk paperwork as explicitly prohibited. I concur with Dren it’s not shown in the Sectional Appendix, but our route clearance paperwork draws on several sources. There’s also some platforms at Paddington they’re prohibited from, and a raft of restrictions for when they are dead-hauled either round the Greenford Triangle or to Reading.

 

[swt_passenger]

In the line diagrams part of the public Western sectional appendix, on the right hand side, it seems (by its absence) to note that the ADUL doesn’t have ATP. It is written on a couple of the drawings “ATP - UM, DM, UR and DR”.

 

[JN114]

In the line diagrams part of the public Western sectional appendix, on the right hand side, it seems (by its absence) to note that the ADUL doesn’t have ATP. It is written on a couple of the drawings “ATP - UM, DM, UR and DR”.

I think that’s an omission in the sectional appendix, SN190 does have a beacon.

We are largely digressing here. Crossrail’s main capacity constraint is platforming at Paddington at the moment - that’s how the frequency increase will be realised once the sewer opens. A change from AWS/TPWS to ETCS won’t change that unfortunately.

 

[kevin_roche]

Thank you to everyone who has contributed. I was musing on the improvements that would be possible when the Elizabeth line opens and there is an increase in traffic on the UR and DR lines. There are plans for a lot more trains once that happens, making it a 5-minute gap between trains for most of the day. Even in the off-peak the addition of the GWR trains from Didcot mean that there will likely be 11tph.

That is just passenger trains. I have ignored adding a freight train every hour which would make it 12tph and 5-minute gaps because I think they only go to and from Acton Yard from the west. Is that correct?

Once the new HS2 station at Old Oak is open, turning all the Elizabeth line trains around there means 24tph in the peak and 21tph off-peak for passenger trains. So that's quite an increase. I wonder what the plans are in that case if any of the main lines are closed. I guess they could still turn trains around at Westbourne park in that case.

 

[Horizon22]

They never have been - I don’t know exactly why though. Few platforms at Paddington they’re banned from as well.

Platforms 8 & 14.

 

[Nippy]

Platforms 8 & 14.

And 1 and 2.

8 has only just been banned, after 20+ years of being used

 

[Horizon22]

And 1 and 2.

8 has only just been banned, after 20+ years of being used

Indeed. Nobody seems quite sure as to what the restrictions are though and why but someone from the GWR & HEX Standards team was involved I'm led to believe. 332s will soon be history anyway!