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20 hours ago, St. Simon said:


Not yet, they are not approved to use the GW OLE yet, nothing is apart from Class 80xs and Class 387s
 

Simon

 

345s are running daily to Reading so one presumes they are doing so with approval.  An 87 also went to Didcot a while back.

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55 minutes ago, DY444 said:

 

345s are running daily to Reading so one presumes they are doing so with approval.  An 87 also went to Didcot a while back.

 

Oh yes, I forgot about the 345s!

 

The 87 wasn't approved for daily use, just a one off charter.

 

Simon

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Bumping this topic, does anyone know if/when the bridge replacement at Patchway has been rescheduled for? It was due to happen end of March, but got postponed due C-19.

(I know it's not strictly a GWML electrification project, but this seems the most appropriate topic).

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  • 4 weeks later...

An interesting development found buried away in the GWR internal weekly newsletter:

 

"We are working with NR to secure the funding to progress the development of electrification between Acton Wells Junction and Acton West Junction (aka The Poplars) and between Didcot and Oxford, extending to Hanborough. This has been approved at the Great Western & Wales Programme Board and we waiting for are wider Government sign-off to release the funds.   "

 

I'm not sure how the Poplar is of any interest to GWR but it's certainly of huge benefit to the freight sector and would allow AC locos to run through from London and beyond to Stoke Gifford, East Usk, ADJ and Wentloog, if they electrify a reception road or two at these locations. Then of course the Class 88 discussion on the last page speaks for itself!

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Being able to run electric trains to other parts of the network might offer GWR and kind of benefit, though it would be pretty marginal.

 

Oxford really has to happen - the substation at Radley was built before the line was cancelled, though extending to Hanborough is unexpected. Guess that would be a new/ extended local train service or just a bit more electric mileage from the bi-modes.

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2 hours ago, Geoff Endacott said:

What about Chippenham, Bath and Bristol Temple Meads?

 

Geoff Endacott

Having been remodeled in the last few years, Oxford probably doesn't need much work doing other than the electrification itself, so can be done relatively quickly.  There's also an immediate operational benefit of getting rid of the current inefficient and unattractive service where some trains terminate at Didcot that would more logically continue to Oxford, so probably also displacing some Turbo units.  

 

Electrifying the route via Bath wouldn't eliminate any DMUs so there is only the relatively marginal benefit of allowing the bi-modes to run for longer in electric mode.  It also needs the big remodeling job of Temple Meads to be finished first. 

 

So of the two it makes more sense to prioritise Oxford.  

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6 minutes ago, Edwin_m said:

Having been remodeled in the last few years, Oxford probably doesn't need much work doing other than the electrification itself, so can be done relatively quickly.  There's also an immediate operational benefit of getting rid of the current inefficient and unattractive service where some trains terminate at Didcot that would more logically continue to Oxford, so probably also displacing some Turbo units.  

 

Electrifying the route via Bath wouldn't eliminate any DMUs so there is only the relatively marginal benefit of allowing the bi-modes to run for longer in electric mode.  It also needs the big remodeling job of Temple Meads to be finished first. 

 

So of the two it makes more sense to prioritise Oxford.  

Plus the useful consideration in respect of Oxford that a lot of the work is already in place such as masts (some) and manyt base tubes (quite a lot).  Can we now expect a Battle of Culham to go along with the Battle of Steventon Bridge?

 

Incidentally a couple of days ago I drove along the road which roughly parallels the railway between north and south stoke - where the ohle structures were the ones that prompted the start of the 'Goring moans'  with photos featured in several places to show how bad they were.  They were not at all noticeable looking across from the road (although might be a bit more obvious once the leaves are of the trees which stand behind them when viewed from the north.

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3 hours ago, Edwin_m said:

Having been remodeled in the last few years, Oxford probably doesn't need much work doing other than the electrification itself, so can be done relatively quickly.  .  

Not so!

 

As far as I know NONE of the existing at Oxford is AC immune (neither is Bristol Temple Meeds - moving the control desk to somewhere else via a TDM communication system does nothing to alter the outside equipment). This means that significant and costly signalling modernisation would be needed even if you wished to retain the current layout!

 

However there is a long held desire to rebuild Oxford station so as to add an additional 3rd through platform. Needless to say this will involve considerable track and signal alterations compared to what exists now. Quite sensibly NR realise that putting in new signalling and all the OLE infrastructure only to have to mess round with it a couple of years later is a massive waste of money and resources and thus electrification to Oxford has always been dependent on ensuring the plan to rebuild Oxford station happens either before or at the same time as electrification.

 

The problem with that is that Oxford Council can't make up their mind exactly what sort of station they want as part of the rebuild which needs resolving as it impacts the future track layout, etc. NRs problems with the wider GWML scheme and the cut backs actually did Oxford Council a favour in this respect as their procrastination was effectively hidden by NRs failings.

 

 

 

Edited by phil-b259
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1 hour ago, phil-b259 said:

Not so!

 

As far as I know NONE of the existing at Oxford is AC immune (neither is Bristol Temple Meeds - moving the control desk to somewhere else via a TDM communication system does nothing to alter the outside equipment). This means that significant and costly signalling modernisation would be needed even if you wished to retain the current layout!

 

 

However there is a long held desire to rebuild Oxford station so as to add an additional 3rd platform. Needless to say this will involve considerable track and signal alterations compared to what exists now. Quite sensibly NR realise that putting in new signalling and all the OLE infrastructure only to have to mess round with it a couple of years later is a massive waste of money and resources and thus electrification to Oxford has always been dependent on ensuring the plan to rebuild Oxford station happens either before or at the same time as electrification.

 

 


Hi Phil,

 

Didcot to Banbury, same as Temple Meads, has not long gone under a full resignalling, taking into account AC Electrification, so it will be AC Immune.

 

The alterations to the signalling from what is there now to add a 4th platform, isn’t that complex actually and was taken into account as part of the resignalling works.

 

Simon 

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I still live in hope of seeing electric trains in Oxford during my lifetime ! The proposed infrastructure improvements (as opposed to station buildings) at Oxford are AFAIK simply turning platform 4 into an island to provide an additional through platform, which I wouldn't have thought would require major alterations to the signalling or, if (hopefully) installed first, the OLE, as St.Simon says. 

 

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1 hour ago, St. Simon said:


Hi Phil,

 

Didcot to Banbury, same as Temple Meads, has not long gone under a full resignalling, taking into account AC Electrification, so it will be AC Immune.

 

The alterations to the signalling from what is there now to add a 4th platform, isn’t that complex actually and was taken into account as part of the resignalling works.

 

Simon 

 

Interesting - I was sure the works at Temple Meeds amounted to a re-control rather than a full resignalling in a bid to cut costs as part of the de scoping of the electrification proposal.

 

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26 minutes ago, caradoc said:

I still live in hope of seeing electric trains in Oxford during my lifetime ! The proposed infrastructure improvements (as opposed to station buildings) at Oxford are AFAIK simply turning platform 4 into an island to provide an additional through platform, which I wouldn't have thought would require major alterations to the signalling or, if (hopefully) installed first, the OLE, as St.Simon says. 

 

 

It rather depends on whether your signal engineers plonk brand new signalling equipment cases and cable runs where you want to lay track. The same is true with OLE masts, etc.

 

If 'passive provision' has been made (as Simon says it has) then obviously adding the extra track at a later stage is easy and relatively cheap.

 

On the other hand 'passive provision' can also end up increasing costs which either sinks the BCR of the scheme or you end up with a M23 junction 7 scenario (expensively built motorway bridges that will never get used) because the requirements change.

 

With Network Rail under the thumb of HM Treasury these days - and seeing how the same department actively discourages any passive provision on the road network it is not impossible that projects seen as wasteful (i.e. we don't need electrification because bionic duckweed can do the same at half the cost) may need to be 'trimmed' to reduce perceived waste / unnecessary expenditure.

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14 minutes ago, phil-b259 said:

 

It rather depends on whether your signal engineers plonk brand new signalling equipment cases and cable runs where you want to lay track. The same is true with OLE masts, etc.

 

If 'passive provision' has been made (as Simon says it has) then obviously adding the extra track at a later stage is easy and relatively cheap.

 

On the other hand 'passive provision' can also end up increasing costs which either sinks the BCR of the scheme or you end up with a M23 junction 7 scenario (expensively built motorway bridges that will never get used) because the requirements change.


Hi,

 

The full signalling design for the Island Platform has already been completed so putting equipment where it clashes (unless it really needs to) with new track will be very very minimal.

 

Simon

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1 hour ago, phil-b259 said:

 

Interesting - I was sure the works at Temple Meeds amounted to a re-control rather than a full resignalling in a bid to cut costs as part of the de scoping of the electrification proposal.

 


It may not be a full resignalling, but it was certainly enough to make everything AC Immune.

 

Theres more signalling work to do I believe, but I think that’s more to improve operations slightly rather than to allow electrification.

 

Simon

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3 minutes ago, St. Simon said:


It may not be a full resignalling, but it was certainly enough to make everything AC Immune.

 

Theres no signalling work to do I believe, but I think that’s more to improve operations slightly rather than to allow electrification.

 

Simon

I was under the impression it was similar to Reading, in that they started by re-signaling essentially the existing track layout with the only major change being back-to-back signals in place of the St Andrew's Crosses at the midpoint of the long platforms.  The signaling is now computer-based and therefore reconfigurable as the layout changes without re-wiring hundreds of relays, and this will facilitate a re-modelling of at least the eastern end which is much easier to do before electrification than after.  

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44 minutes ago, Edwin_m said:

 The signaling is now computer-based and therefore reconfigurable as the layout changes without re-wiring hundreds of relays, and this will facilitate a re-modelling of at least the eastern end which is much easier to do before electrification than after.  


If only making changes were easy as fiddling with the computer.

 

It is just as complex, as much effort and as much cost to alter CBIs as it is an RRI, but in terms of data and screen changes rather than physical wiring. The thing that would make a remodelling easier is that fact with a CBI you have far greater capacity for adding TFMs before you ‘run out puff’ and have to buy another one.

 

Never let anyone tell you altering CBIs is easy! :) 


Simon

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7 minutes ago, SouthernMafia said:

 

Thanks Simon, that's interesting. Where are we going to end up, Euston?


Waterloo has been talked about, but I’m not sure what the latest thinking is

 

Although I think it’s also to allow an electric unit somewhere else to turn back at Ealing Broadway during the works.

 

Simon

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1 hour ago, Edwin_m said:

I was under the impression it was similar to Reading, in that they started by re-signaling essentially the existing track layout with the only major change being back-to-back signals in place of the St Andrew's Crosses at the midpoint of the long platforms.  The signaling is now computer-based and therefore reconfigurable as the layout changes without re-wiring hundreds of relays, and this will facilitate a re-modelling of at least the eastern end which is much easier to do before electrification than after.  

 

Generally the thing that makes an area AC immune is the type of track circuits used - not the interlocking! (yes I know there is the requirements to bond every metal structure to the running rails among other things - but that won't affect the signalling kit)

 

For example if the ORR were to permit the electrification of the Uckfield line absolutely no changes would be needed to the interlocking or lineside signals - but virtually every track circuit would need changing from the basic DC voltage based type to a more expensive and complex AC based version to make them 'DC immune'.

 

Now I'm not too clued up on what is the preferred type of track circuit under OLE - but given most of the stuff around Bristol and Oxford would have been installed on the assumption it never needed to worry about OLE restrictions, its quite possible that incompatibilities exist between what is installed and what is allowed in OLE areas.

 

As for Computer based interlockings in general, their big advantage in operational terms is they are more reliable and have grater logging abilities than a relay based one (which was why Kings Cross got a new CBI / SSI interlocking a few years back - but with the trackside modules actually bolted to the wall of the relay room feeding the late 1970s era outside kit by the existing cabling and driven by a good old fashioned NX panel). The down side is that you cannot easily tweak them if a flaw / omission* is discovered without spending lots of money getting Siemens / Alstom to re-write the software.

 

* There have been at least 2 incidents to my knowledge where the programmer has made errors which could have resulted in nasty train crashes had circumstances been different. One occurred on the WCML at Milton Keynes around a decade ago where a track circuit was missed out of the programming completely and had the potential to replicate the for a Clapham junction smash, while another was identified following a points run through at Tonbridge a year later in the British Rail installed 1992 software at Ashford IECC.

 

 

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6 hours ago, Edwin_m said:

Having been remodeled in the last few years, Oxford probably doesn't need much work doing other than the electrification itself, so can be done relatively quickly.  There's also an immediate operational benefit of getting rid of the current inefficient and unattractive service where some trains terminate at Didcot that would more logically continue to Oxford, so probably also displacing some Turbo units.  

 

Electrifying the route via Bath wouldn't eliminate any DMUs so there is only the relatively marginal benefit of allowing the bi-modes to run for longer in electric mode.  It also needs the big remodeling job of Temple Meads to be finished first. 

 

So of the two it makes more sense to prioritise Oxford.  

I had an idea that Chiltern wanted to extend their Marylebone to Oxford service by having trains continue past Oxford to Kennington Junction, Littlemore and Cowley. That would have involved extending the present Platform 1 running line through the present booking office(!) so is the remodelling of Oxford really now considered finished?

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10 hours ago, St. Simon said:


If only making changes were easy as fiddling with the computer.

 

It is just as complex, as much effort and as much cost to alter CBIs as it is an RRI, but in terms of data and screen changes rather than physical wiring. The thing that would make a remodelling easier is that fact with a CBI you have far greater capacity for adding TFMs before you ‘run out puff’ and have to buy another one.

 

Never let anyone tell you altering CBIs is easy! :) 


Simon

Many years ago I was on the IECC support team, so I'm aware of the difficulties of changing the data in a CBI, and I was careful not to suggest in my post that it would be easy.  The critical point here is that with a CBI most of the work to change the track layout is done beforehand and offline, whereas with a relay interlocking it involves physically changing the wiring on site.  

8 hours ago, phil-b259 said:

 

Generally the thing that makes an area AC immune is the type of track circuits used - not the interlocking! (yes I know there is the requirements to bond every metal structure to the running rails among other things - but that won't affect the signalling kit)

 

For example if the ORR were to permit the electrification of the Uckfield line absolutely no changes would be needed to the interlocking or lineside signals - but virtually every track circuit would need changing from the basic DC voltage based type to a more expensive and complex AC based version to make them 'DC immune'.

 

Now I'm not too clued up on what is the preferred type of track circuit under OLE - but given most of the stuff around Bristol and Oxford would have been installed on the assumption it never needed to worry about OLE restrictions, its quite possible that incompatibilities exist between what is installed and what is allowed in OLE areas.

 

As for Computer based interlockings in general, their big advantage in operational terms is they are more reliable and have grater logging abilities than a relay based one (which was why Kings Cross got a new CBI / SSI interlocking a few years back - but with the trackside modules actually bolted to the wall of the relay room feeding the late 1970s era outside kit by the existing cabling and driven by a good old fashioned NX panel). The down side is that you cannot easily tweak them if a flaw / omission* is discovered without spending lots of money getting Siemens / Alstom to re-write the software.

 

* There have been at least 2 incidents to my knowledge where the programmer has made errors which could have resulted in nasty train crashes had circumstances been different. One occurred on the WCML at Milton Keynes around a decade ago where a track circuit was missed out of the programming completely and had the potential to replicate the for a Clapham junction smash, while another was identified following a points run through at Tonbridge a year later in the British Rail installed 1992 software at Ashford IECC.

I would be extremely surprised if the re-signaling at Temple Meads left it with any non-immune track circuits.  Immune types are pretty much standard these days for new installations.  

 

Errors in requirements. specification and design can occur regardless of how that design is actually implemented, so checking and testing is needed that is sufficiently thorough while being appropriate to the type of technology being used.  See for example the collision at Waterloo a couple of years ago, caused by making temporary changes to a relay interlocking.  With computer-based interlocking more of this checking can be done on simulators and other off-line test equipment.  

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2 hours ago, Edwin_m said:

 

I would be extremely surprised if the re-signalling at Temple Meads left it with any non-immune track circuits.  Immune types are pretty much standard these days for new installations.  

 

 

But Simon has stated Bristol was NOT resignalled (as is traditionally thought of) - hence the point. Obviously its quite possible there is a programme of track circuit conversion going on in the area* - but this sort of thing doesn't really count as 'resignalling' in the traditional sense as no alterations to signal positions or track layout are made under such a programme.

 

Its no different to a programme of changing signal heads to LEDS or point drive mechanisms from machines to hydraulic operated. Effectively they are operationally equivalent and require no changes to the brains of the system (the interlocking) to carry out.

 

Similarly the Kings Cross example was not really a resignalling - only the interlocking itself was changed with the control panel and outside kit staying the same. More widely the replacement of London Bridge ASC has seen examples of complete resignalling taking place, re-control where the existing interlocking and outside equipment remains unchanged and places where re-control and a new interlocking has been added but re-used the outside kit unchanged.

 

It is therefore quite possible that one of these later strategies has been adopted for the Bristol area - possibly in combination with a track circuit conversion programme both of which could effectively make the area AC immune without a traditional resignalling project having taken place.

 

* Down in Sussex we have an ongoing programme replace the obsolete 'Reed' type of track circuit with the EBI type - mainly on the grounds of real time logging / diagnostic ability plus the reduced routine servicing time techs the modern EBI types bring.

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1 hour ago, phil-b259 said:

 

But Simon has stated Bristol was NOT resignalled (as is traditionally thought of) - hence the point. Obviously its quite possible there is a programme of track circuit conversion going on in the area* - but this sort of thing doesn't really count as 'resignalling' in the traditional sense as no alterations to signal positions or track layout are made under such a programme.

 

Its no different to a programme of changing signal heads to LEDS or point drive mechanisms from machines to hydraulic operated. Effectively they are operationally equivalent and require no changes to the brains of the system (the interlocking) to carry out.

 

Similarly the Kings Cross example was not really a resignalling - only the interlocking itself was changed with the control panel and outside kit staying the same. More widely the replacement of London Bridge ASC has seen examples of complete resignalling taking place, re-control where the existing interlocking and outside equipment remains unchanged and places where re-control and a new interlocking has been added but re-used the outside kit unchanged.

 

It is therefore quite possible that one of these later strategies has been adopted for the Bristol area - possibly in combination with a track circuit conversion programme both of which could effectively make the area AC immune without a traditional resignalling project having taken place.

 

* Down in Sussex we have an ongoing programme replace the obsolete 'Reed' type of track circuit with the EBI type - mainly on the grounds of real time logging / diagnostic ability plus the reduced routine servicing time techs the modern EBI types bring.

 

He said...

15 hours ago, St. Simon said:

It may not be a full resignalling, but it was certainly enough to make everything AC Immune.

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