Should East-West Rail (EWR) signalling be fully bi-directional?

[II]

Moderator note: Split from https://railforums.co.uk/threads/east-west-rail-ewr-oxford-bletchley-construction-progress.216561/

I think that EWR from Bicester towards Bletchley will not now be bi-directional. Since the most recent signalling changes in August 2021, Signal OB1787 at Bicester Village now only has a position 4 junction indicator for the route towards Bicester South Jn and Marylebone. This route used to be position 5 (4 previously being towards Bletchley ie down direction on the up line).

== Doublepost prevention - post automatically merged: 12 Sep 2022 ==

Before and after signalling changes at Bicester Village. First picture (August 2021) shows the route set towards Marylebone. The second picture is dated November 2021.

Indeed, and a bit of a pity as bi-di is always a very useful feature in the event of problems (i.e. train/signal failure, track defects etc) and the length of the route and intermediate crossovers at Claydon would be just about the right length to have signals controlling 'wrong' direction movements at either ends of those sections - but no need for any in-between as I don't think there's any infrastructure that would demand them such as level crossings?

Some ground position signal are being installed for shunting movements, and with the Oxford to Bicester section having bi-di signalling (as well as the Chiltern Line in the area) it seems a rather inconsistent decision not to make it bi-di?

The signalmaps map https://signalmaps.co.uk/#claydon:1131 shows the location of new signals. Not quite including Bicester Village, but you can see the absence of any bi-directional sections, other than from Bletchley to Bletchley West Junction.

 

[The Planner]

Indeed, and a bit of a pity as bi-di is always a very useful feature in the event of problems (i.e. train/signal failure, track defects etc) and the length of the route and intermediate crossovers at Claydon would be just about the right length to have signals controlling 'wrong' direction movements at either ends of those sections - but no need for any in-between as I don't think there's any infrastructure that would demand them such as level crossings?

Some ground position signal are being installed for shunting movements, and with the Oxford to Bicester section having bi-di signalling (as well as the Chiltern Line in the area) it seems a rather inconsistent decision not to make it bi-di?

The signalmaps map https://signalmaps.co.uk/#claydon:1131 shows the location of new signals. Not quite including Bicester Village, but you can see the absence of any bi-directional sections, other than from Bletchley to Bletchley West Junction.

There is no bi-di at all apart from Bletchley, cost would have put paid to any notion of it.

 

[zwk500]

There is no bi-di at all apart from Bletchley, cost would have put paid to any notion of it.

Is Bletchley full bi-di or does it just permit reversals?

 

[II]

There is no bi-di at all apart from Bletchley, cost would have put paid to any notion of it.

Yes, that's what my post said.

Whilst also pointing out that bi-di was included in the spec of other areas nearby which have recently been reopened or resignalled where cost didn't put paid to any notion of it. Given that and the future potential strategic importance of the route that strikes me as a little inconsistent. Perhaps it will be added, at additional cost, at a later date?

In the main though I'm just glad it's reopening and works to that aim are proceeding well.

 

[The Planner]

Is Bletchley full bi-di or does it just permit reversals?

Reversals to from Bicester.

== Doublepost prevention - post automatically merged: 13 Sep 2022 ==

Perhaps it will be added, at additional cost, at a later date?

Doubt it, considering the issues with electrifying it in the first place.

 

[II]

Is Bletchley full bi-di or does it just permit reversals?

Just reversals I believe.

== Doublepost prevention - post automatically merged: 13 Sep 2022 ==

Doubt it, considering the issues with electrifying it in the first place.

Not sure what electrification has to do with it? What is the connection between electrification and retro fitting bi-di signalling?

 

[zwk500]

Not sure what electrification has to do with it? What is the connection between electrification and retro fitting bi-di signalling?

They both were dropped for cost. Also, if you're going to electrify the line at some point signal sighting needs to be considered.]

Bi-Di will probably wait until ETCS L2 comes in on EWR. Electrification might come sooner than that, or at the same time.

 

[II]

They both were dropped for cost. Also, if you're going to electrify the line at some point signal sighting needs to be considered.]

Bi-Di will probably wait until ETCS L2 comes in on EWR. Electrification might come sooner than that, or at the same time.

Electrification costs (which of course would have to be all the way from Didcot/Oxford, not just Bicester) would rather swamp the cost of installing a handful of additional signals for bi-di working with signal sighting considerations.

And yes, it might be a good opportunity to introduce bi-di when ETCS eventually comes about, though it would need to be accelerated from the current plan of CP12 (2049-2054)!

 

[Bald Rick]

Electrification costs (which of course would have to be all the way from Didcot/Oxford, not just Bicester) would rather swamp the cost of installing a handful of additional signals for bi-di working with signal sighting considerations.

And yes, it might be a good opportunity to introduce bi-di when ETCS eventually comes about, though it would need to be accelerated from the current plan of CP12 (2049-2054)!

Bi di is a lot more than ‘a handful of additional signals’. Typically bidi adds at least 50% to the cost of a new conventional signalling installation.

 

[II]

Bi di is a lot more than ‘a handful of additional signals’. Typically bidi adds at least 50% to the cost of a new conventional signalling installation.

That’s interesting. I would be surprised if it was the case on a built-from-scratch route with one set of intermediate crossovers, no existing signalling and no level crossings to complicate things.

Do you think it would be have been a waste of money providing bi-di on the route?

If so, do you think money was wasted providing other recent local bi-di schemes between Aynho<>Princes Risbotough, or Wolvercote<>Didcot, or Oxford<>Bicester?

 

[Bald Rick]

It’s no different really

That’s interesting. I would be surprised if it was the case on a built-from-scratch route with one set of intermediate crossovers, no existing signalling and no level crossings to complicate things.

Do you think it would be have been a waste of money providing bi-di on the route?

If so, do you think money was wasted providing other recent local bi-di schemes between Aynho<>Princes Risbotough, or Wolvercote<>Didcot, or Oxford<>Bicester?

.

it’s little different cost wise between all new and resignalling an existing.

The cost increase is partly more kit in the ground (eg more signals, cabling, train detection, AWS/TPWS, suppression for AWS/TPWS, power, etc), partly a more complicated design, partly a (much) more complicated interlocking (and thus data prep and testing), and partly more testing and commissioning.

On this route I do think it would be a waste if money, given the projected traffic and value of it.

Wolvercote - Didcot: much higher traffic and value, therefore worth doing.

Aynho - Princes Risboro was bidi before the redoubling, so the extra cost was smaller.

Oxford - Bicester looks superfluous to me.

 

[Nicholas Lewis]

Bi di is a lot more than ‘a handful of additional signals’. Typically bidi adds at least 50% to the cost of a new conventional signalling installation.

Full bi di adds the costs of the additional signals but is SimBids now out of favour?

 

[II]

It’s no different really

.

it’s little different cost wise between all new and resignalling an existing.

The cost increase is partly more kit in the ground (eg more signals, cabling, train detection, AWS/TPWS, suppression for AWS/TPWS, power, etc), partly a more complicated design, partly a (much) more complicated interlocking (and thus data prep and testing), and partly more testing and commissioning.

On this route I do think it would be a waste if money, given the projected traffic and value of it.

Wolvercote - Didcot: much higher traffic and value, therefore worth doing.

Aynho - Princes Risboro was bidi before the redoubling, so the extra cost was smaller.

Oxford - Bicester looks superfluous to me.

I guess in order to give a more informed opinion we’d need to know what the cost of the standard installation is going to be against what the cost of bi-di would have been.

I don’t suppose you or anyone else knows those figures?

Or for that matter the cost of the bi-di that was provided between Oxford<>Bicester and why that was justified and chosen over the cost of a standard installation.

 

[MarkyT]

Full bi di adds the costs of the additional signals but is SimBids now out of favour?

If by SimBids you mean reduced capacity signalling in the reverse direction compared to the normal direction, i.e fewer signals, then that is still an option for modern schemes. The 'real' Simbids implemented in various parts of Eastern and Western Regions, in addition to reduced capacity in the reverse direction also avoided any new AWS equipment for reverse direction movements and didn't suppress the normal direction AWS magnets, covering the situation with some special signage invented for the application. Simplified aspects sequences were also permitted, and economies on numbers of trackside telephones. This was a particular engineering solution to allow reverse direction signalling to be added at a reduced cost to existing relay signalled areas, saving much cabling as well as the new equipment mentioned. This type of installation is not permitted today, with full AWS and TPWS being required on the usual risk-ranked basis.

 

[Nicholas Lewis]

If by SimBids you mean reduced capacity signalling in the reverse direction compared to the normal direction, i.e fewer signals, then that is still an option for modern schemes. The 'real' Simbids implemented in various parts of Eastern and Western Regions, in addition to reduced capacity in the reverse direction also avoided any new AWS equipment for reverse direction movements and didn't suppress the normal direction AWS magnets, covering the situation with some special signage invented for the application. Simplified aspects sequences were also permitted, and economies on numbers of trackside telephones. This was a particular engineering solution to allow reverse direction signalling to be added at a reduced cost to existing relay signalled areas, saving much cabling as well as the new equipment mentioned. This type of installation is not permitted today, with full AWS and TPWS being required on the usual risk-ranked basis.

Thanks for clarity and that was the sort of scheme i was thinking of. So as usual in the industry we would rather not have a slight risk and just have trains sat down all over the place when incidents occur.

 

[Andyjs247]

My understanding is that Simbids is only available for use during possessions or in the case of some other exceptional incident, eg a failure. Other than for possessions it is not available for planned use.

Full bi di allows reverse direction moves to be planned. In practice you still need reverse direction SRTs and somewhere suitable to cross over from/to normal direction running. Long sections of bi di without crossovers are unlikely to get much use though. On the Oxford Parkway-Bicester section there was some timetabled use of the bi di in the reverse direction during the first year of operations but probably not been used much since.

Woodstock Road Jn-Oxford North Jn was effectively used as a single line for quite some time until Oxford North Jn was fully restored to having parallel connections, and allowed the work there to be done later. The bi di also allows something to be looped without actually having a loop and does give additional flexibility. In combination with strategically located crossing points trains can and do overtake others eg at Bicester North, Oxford Parkway etc if required using the bi di.

 

[MarkyT]

My understanding is that Simbids is only available for use during possessions or in the case of some other exceptional incident, eg a failure. Other than for possessions it is not available for planned use.

That was the case on the Western. Planned usage had to be published beforehand in an operating notice.

Full bi di allows reverse direction moves to be planned. In practice you still need reverse direction SRTs and somewhere suitable to cross over from/to normal direction running. Long sections of bi di without crossovers are unlikely to get much use though.

On high speed sections of the GWML, reverse direction moves are typically subject to lower speed limits than normal direction on the same track. You've also usually got to slow down even more to pass through the crossovers.

On the Oxford Parkway-Bicester section there was some timetabled use of the bi di in the reverse direction during the first year of operations but probably not been used much since. Woodstock Road Jn-Oxford North Jn was effectively used as a single line for quite some time until Oxford North Jn was fully restored to having parallel connections, and allowed the work there to be done later. The bi di also allows something to be looped without actually having a loop and does give additional flexibility. In combination with strategically located crossing points trains can and do overtake others eg at Bicester North, Oxford Parkway etc if required using the bi di.

Oxford N -Bicester is quite a short section with two freight sidings en route. Don't know if there's actually any regular traffic for these, but if and when any such trains run, they might be able to utilise the bidi for greater flexibility, or it might be used to allow passenger trains to weave around such freight, especially if it presents out of course.

 

[LNW-GW Joint]

I haven't followed the detail of EWR design and construction.
Will bi-di signalling be provided?
Will the track centres be further apart than normal to allow maintenance on one line while running services on the other?
You know, like virtually every main line on the continent...

 

[zwk500]

Will bi-di signalling be provided?

On Bicester-Bletchley, the only reversible signalling will be to allow trains to terminate at Bletchley and return West.

Will the track centres be further apart than normal to allow maintenance on one line while running services on the other?

No, it will be built to standard track centres.

You know, like virtually every main line on the continent...

Remember that this part of EWR is technically a renovation of an existing line, not a new-build.

 

[12LDA28C]

On Bicester-Bletchley, the only reversible signalling will be to allow trains to terminate at Bletchley and return West.


Remember that this part of EWR is technically a renovation of an existing line, not a new-build.

And yet the Western end of the route between Gavray Junction and Oxford is fully bi-directional, seems the project has been scaled back since that section opened for traffic, which was also 'technically' a renovation of an existing line.

 

[zwk500]

And yet the Western end of the route between Gavray Junction and Oxford is fully bi-directional, seems the project has been scaled back since that section opened for traffic, which was also 'technically' a renovation of an existing line.

Oxford Parkway to Bicester is not fully Bi-di, the wrong-direction signals only permit one train in section rather than the minimum headway. I agree it's a scaled back section - although my comment about the existing line was related to track centres not signalling.
I don't know if it was ever scoped for full bi-di, but if it was it likely went when electrification was also cut, in the interests of getting the damn thing built. Bicester-Oxford does have a higher justification for Bi-di though, due to it carrying London traffic and the potential need to manage stacking traffic outside Oxford if there were problems. It also facilitates a bit of marginal extra STP capacity and short turnrounds on a section likely to be significantly impacted by disruption from either end.
The additional cost of bi-di signalling and Facing/trailing crossovers is tempered against the much lower chance of disruption and potential need for short working. It would have been nice if Bi-di working had been put in using Claydon as a crossover point, but given the traffic on offer (2tph with 3-car DMUs and the occasional freight) is it worth it? Turning short at Bletchley is an obvious provision to include in case the WCML stuffs up, even if it would have been nicer if they had included crossovers on the Denbigh hall side to make Bletchley fully bi-di rather than just easier to reverse inonde direction from.

 

[The Planner]

Will the track centres be further apart than normal to allow maintenance on one line while running services on the other?
You know, like virtually every main line on the continent...

You would be rebuilding every bridge to do that and probably also messing with boundaries, it will have a standard 6 foot.

 

[12LDA28C]

Oxford Parkway to Bicester is not fully Bi-di, the wrong-direction signals only permit one train in section rather than the minimum headway. I agree it's a scaled back section - although my comment about the existing line was related to track centres not signalling

Ok I'll rephrase - it's bi-directionally signalled along the full length of the route although granted the 'wrong direction' sections are very long, and rarely used.

 

[The Planner]

Oxford Parkway to Bicester is not fully Bi-di, the wrong-direction signals only permit one train in section rather than the minimum headway. I agree it's a scaled back section - although my comment about the existing line was related to track centres not signalling.
I don't know if it was ever scoped for full bi-di, but if it was it likely went when electrification was also cut, in the interests of getting the damn thing built. Bicester-Oxford does have a higher justification for Bi-di though, due to it carrying London traffic and the potential need to manage stacking traffic outside Oxford if there were problems. It also facilitates a bit of marginal extra STP capacity and short turnrounds on a section likely to be significantly impacted by disruption from either end.
The additional cost of bi-di signalling and Facing/trailing crossovers is tempered against the much lower chance of disruption and potential need for short working. It would have been nice if Bi-di working had been put in using Claydon as a crossover point, but given the traffic on offer (2tph with 3-car DMUs and the occasional freight) is it worth it? Turning short at Bletchley is an obvious provision to include in case the WCML stuffs up, even if it would have been nicer if they had included crossovers on the Denbigh hall side to make Bletchley fully bi-di rather than just easier to reverse inonde direction from.

It was originally having 4 aspect signalling, but that is now 3.

 

[zwk500]

Ok I'll rephrase - it's bi-directionally signalled along the full length of the route although granted the 'wrong direction' sections are very long, and rarely used.

FWIW, I agree that it's frustrating that the SIMBIDS-type signalling (I'm not sure what it's counted as nowadays) wasn't provided from Bicester to Claydon and Claydon to Bletchley, but if it becomes obviously needed it can be fitted later, and it was more important (like electrification) to get the railway built in some form than to try and build the railway we'd like to have.

== Doublepost prevention - post automatically merged: 13 Apr 2023 ==

It was originally having 4 aspect signalling, but that is now 3.

3-Aspect is surprising for a line that is apparently going to have 3-minute headways! Do you know if any form of Bi-Di between Bicester and Bletchley was proposed back in the heady days when Electrification was still included?

 

[The Planner]

FWIW, I agree that it's frustrating that the SIMBIDS-type signalling (I'm not sure what it's counted as nowadays) wasn't provided from Bicester to Claydon and Claydon to Bletchley, but if it becomes obviously needed it can be fitted later, and it was more important (like electrification) to get the railway built in some form than to try and build the railway we'd like to have.

== Doublepost prevention - post automatically merged: 13 Apr 2023 ==


3-Aspect is surprising for a line that is apparently going to have 3-minute headways! Do you know if any form of Bi-Di between Bicester and Bletchley was proposed back in the heady days when Electrification was still included?

They aren't 3 minute headways, 4 minutes. The oldest plan I have is Feb 2020 and bi-di isn't on that.

 

[12LDA28C]

3-Aspect is surprising for a line that is apparently going to have 3-minute headways!

Why would you need 3-minute headways for a half-hourly passenger train service and the occasional freight? I appreciate the need to provide capacity for more trains to run in the future but that seems over-provision in the extreme.

 

[zwk500]

Why would you need 3-minute headways for a half-hourly passenger train service and the occasional freight? I appreciate the need to provide capacity for more trains to run in the future but that seems over-provision in the extreme.

As @The Planner has pointed out I hadn't quite read the infrastructure spec carefully enough but the technical appendices to the consultation say:

5.7.2. Train Planning headways between Bicester and (excluding Bletchley to Milton Keynes) the connection to Network Rail infrastructure as part of the approach to Cambridge shall be no greater than 3 minutes.
5.7.2.1. If EWR Co proceeds with Configuration Option 2.5, the headways between Aylesbury and Claydon shall be no greater than 8 minutes.

 

[The Planner]

As @The Planner has pointed out I hadn't quite read the infrastructure spec carefully enough but the technical appendices to the consultation say:

They have clearly been put in the bin then.

 

[BrianW]

Oxford Parkway to Bicester is not fully Bi-di, the wrong-direction signals only permit one train in section rather than the minimum headway. I agree it's a scaled back section - although my comment about the existing line was related to track centres not signalling.
I don't know if it was ever scoped for full bi-di, but if it was it likely went when electrification was also cut, in the interests of getting the damn thing built. Bicester-Oxford does have a higher justification for Bi-di though, due to it carrying London traffic and the potential need to manage stacking traffic outside Oxford if there were problems. It also facilitates a bit of marginal extra STP capacity and short turnrounds on a section likely to be significantly impacted by disruption from either end.
The additional cost of bi-di signalling and Facing/trailing crossovers is tempered against the much lower chance of disruption and potential need for short working. It would have been nice if Bi-di working had been put in using Claydon as a crossover point, but given the traffic on offer (2tph with 3-car DMUs and the occasional freight) is it worth it? Turning short at Bletchley is an obvious provision to include in case the WCML stuffs up, even if it would have been nicer if they had included crossovers on the Denbigh hall side to make Bletchley fully bi-di rather than just easier to reverse inonde direction from.

IIRC (which I might not!) as the service to Oxford Parkway and then to Oxford started up there were trains departed from both platforms at Bicester Village towards Marylebone, (some?) travelling 'wrong line' up to the junction with the 'main line'. I don't recall the signalling arrangements.