Heathrow Express GWR Contract

Discussion in 'UK Railway Discussion' started by Sprinter153, 28 Mar 2018.

Thread Status:
Not open for further replies.
  1. hwl

    hwl Established Member

    Messages:
    4,855
    Joined:
    5 Feb 2012
    If the 345s are still getting upset by GW-ATP equipment installed on the GW(reliefs) in open air then not so easy to do an overnight swap.

    Bombardier are being focused by CRL on core signalling issues rather than rolling out solutions for Heathrow (which they apparently already have)
     
  2. Muzer

    Muzer Established Member

    Messages:
    2,716
    Joined:
    3 Feb 2012
    The issue as I understood it was that the 345s' ETCS equipment did not like ATP signals. Obviously both ATP and ETCS are currently present in the Heathrow tunnels, but ATP can be switched off once the 332s and 360s are gone.
     
  3. Muzer

    Muzer Established Member

    Messages:
    2,716
    Joined:
    3 Feb 2012
    345s are running fine on the mainline as they use TPWS there. It is specifically the ETCS equipment that doesn't like the ATP. But good point on that, maybe the interference from the ATP on the mainline is enough to upset the ETCS as the train transitions into the tunnel...
     
  4. Muzer

    Muzer Established Member

    Messages:
    2,716
    Joined:
    3 Feb 2012
    ETCS is (now) fitted on the airport branch. The problem is that 345s don't like both being present at once, as I understand it.
     
  5. cactustwirly

    cactustwirly Established Member

    Messages:
    5,254
    Joined:
    10 Apr 2013
    Location:
    UK
    Yes, they already operate over the mains, as well as the non ATP fitted 16xs as well!
     
  6. paulravuslante

    paulravuslante Member

    Messages:
    426
    Joined:
    19 May 2010
    Location:
    West Drayton
    Yeah, as I understand as well. I don't know if ATP can be temporarily switched off to test 345s in engineering hours. How else could they work around the problem?
     
  7. hwl

    hwl Established Member

    Messages:
    4,855
    Joined:
    5 Feb 2012
    I meant after they have been fitted with ETCS equipment which might cause issues similar to 345s issues
     
  8. MarkyT

    MarkyT Established Member

    Messages:
    3,860
    Joined:
    20 May 2012
    Location:
    Torbay
    The GW-ATP works on the same carrier frequency as the ETCS replacement system. The balises and track loops of GW-ATP have significantly higher radio signal strength than ETCS, and the 1990s engineers also chose to duplicate all the transponders in the tunnel for reliability. There is some kind of 'waveguide propagation' issue that distributes the GW-ATP signal more widely than expected due to the frequency used and the physical dimensions of the tunnel. The ETCS equipment is already provided in the airport tunnels and is I understand connected to the signalling system and powered up in final configuration. GW-ATP also remains connected to the signalling, also powered up to allow continued operation of cl.332 train. ETCS equipped trains cannot be operated reliably in the tunnels due to interference experienced from the stronger ATP signal. There is no way of easily 'switching off' the GW-ATP equipment widely in the tunnels to allow overnight testing of ETCS trains in the short no train periods available. Large numbers of individual fuses have to be individually hand-removed by signal engineering staff in tunnel equipment cabinets to get a useful section of ATP equipment isolated ready for ETCS testing in the final configuration, and it all has to be manually reconnected and verified again before start of service the following morning. Hence the required testing to get cl.379 and cl.345 approved for running in the tunnels is proving very difficult to orchestrate without extended service outages before commissioning.
     
    Last edited: 23 Jan 2019
  9. cactustwirly

    cactustwirly Established Member

    Messages:
    5,254
    Joined:
    10 Apr 2013
    Location:
    UK
    Why was ECTS fitted in the (Heathrow) tunnels instead of TPWS?
     
  10. MarkyT

    MarkyT Established Member

    Messages:
    3,860
    Joined:
    20 May 2012
    Location:
    Torbay
    Mainly because it was not considered safe enough for a high frequency tunnel railway. ETCS is also the chosen longer term solution for GWML from Paddington to Heathrow Airport Junctions and has merely been 'deferred' on the open air segment in favour of 'Plan B' which is known as TPWS+. TPWS+ is described as enhanced TPWS, with all previously unfitted plain line signals and speed restrictions newly equipped with appropriate loops to get close to the protection previously provided by GW-ATP. The derailment containment slab between the rails in the tunnels needs expensive holes cut into it to to accommodate additional transponders which under TPWS could not be in the same position as future ETCS equipment if the two systems are ever to be installed in parallel ready for a future changeover. All this extra work would have to take place in the short overnight no train periods.
     
  11. paulravuslante

    paulravuslante Member

    Messages:
    426
    Joined:
    19 May 2010
    Location:
    West Drayton
    Thanks for the detailed information. Confirms my suspicions.
     
  12. Roy Badami

    Roy Badami Member

    Messages:
    92
    Joined:
    12 Oct 2014
    Well the other way to look at is that ETCS is the future - and given Crossrail trains were already specified with ETCS why wouldnt you fit that rather than TPWS, which is a legacy system.

    As to why TPWS (or even AWS, I think?) were never fitted when the airport branch was built (or subsequently), that's easy too: all the trains using the branch were fitted with GW-ATP so legacy protection systems were completely unnecessary.

    As to the details of the history of ATP introduction that lead to that state of affairs, I'll leave that to others who are more knowledgeable.
     
    Last edited: 23 Jan 2019
  13. paulravuslante

    paulravuslante Member

    Messages:
    426
    Joined:
    19 May 2010
    Location:
    West Drayton
    AWS is fitted on the Heathrow branch.
     
  14. Roy Badami

    Roy Badami Member

    Messages:
    92
    Joined:
    12 Oct 2014
    Thanks, wasn't sure
     
  15. Muzer

    Muzer Established Member

    Messages:
    2,716
    Joined:
    3 Feb 2012
    Yes, the original intention (as I understand it) was that GW-ATP and ETCS would be able to operate side-by-side. I believe this was actually tested and found to be the case ---- but for whatever reason, while it might be the case on ideal test trains, it's not the case on 345s. From what I gather it's the 345s themselves that are considered "at fault" for this --- but I don't know enough about the radio frequencies involved to be able to form my own opinion on who is really at fault here. But you'd have thought they'd have had some radio engineers to confirm whether GW-ATP and ETCS would be able to theoretically run side-by-side or not, so I would imagine as a result that the "problem" item here is the 345s being unable to sufficiently discriminate the ETCS from the GW-ATP signals.

    From the sounds of it, it seems that they've decided that rather than do the "correct" thing and make the 345s better at discriminating between the two competing signals, it would instead be simply easier to wait until the GW-ATP is gone and then have the 345s running on the ETCS alone. But this would require either a problematic transitionary period where you can have one or the other but not both systems running, or an intermediary period where they set up something like TPWS+ only to abandon it once ETCS is working. Neither is particularly a great option...
     
  16. samuelmorris

    samuelmorris Established Member

    Messages:
    4,188
    Joined:
    18 Jul 2013
    Location:
    Brentwood, Essex
    I imagine since GW-ATP is surplus to requirements in future, they decided against further risky modifications to the 345 software, given that is at the centre of the current Crossrail delay.
     
  17. MarkyT

    MarkyT Established Member

    Messages:
    3,860
    Joined:
    20 May 2012
    Location:
    Torbay
    I think any train trying to run on ETCS while GW-ATP is still active in the tunnels is going to run into trouble, because the ATP signals are very much stronger than those of ETCS and the ATP balises and track loops broadcast continuously rather than being interrogated only on passing by the train. The frequency used combined with the particular dimensions of the tunnel cause the signal to bounce along the tunnel acting as a waveguide too.
    I agree that is potentially a lot of difficult expensive work for an outcome that is not required once the GW-ATP is decommissioned in the tunnel. I think the project should invest in a temporary remote switching system to allow isolatation and restoration the GW-ATP equipment in the tunnels quickly so testing of 387s and 345s under ETCS only can take place routinely at night before the big switch over when 387s take over the expresses and and 345s start running to the airport.
     
  18. MarkyT

    MarkyT Established Member

    Messages:
    3,860
    Joined:
    20 May 2012
    Location:
    Torbay
    It should be noted that the Bombardier cl.387 has exactly the same train control management system on board as the same manufacturer's cl.345, just without the cab control screens already enabled for ETCS. The cabs and systems have been designed carefully with retrofitting in mind however, as have all similar Bombardier trains since the 379s apparently. Inevitably, the challenges faced on the 345s will be shared by the 387s although equally the lessons learned from the Elizabeth trains should be transferable too.
     
  19. gwr4090

    gwr4090 Member

    Messages:
    144
    Joined:
    9 Nov 2011
    Is the GWR-ATP interference problem with ETCS just in the Heathrow tunnels or is it more general ? I note that the fitting of ETCS to the GW main line from Paddington-Bristol Parkway has apparently been cancelled. It should have been completed by now but Network Rail is totally silent about what is going on. There doesnt seem to be any coherent strategy. The latest Digital Strategy paper merely states that funds have been set aside to investigate the possible life extension of GWR-ATP.
     
  20. edwin_m

    edwin_m Veteran Member

    Messages:
    16,933
    Joined:
    21 Apr 2013
    Location:
    Nottingham
    Modifying the software and completed the necessary testing and safety approvals would most likely take longer than the current plan.
     
  21. matt_world2004

    matt_world2004 Established Member

    Messages:
    2,435
    Joined:
    5 Nov 2014
    If the plan is for gw-ATP to be turned off over night and 345s/387s running the next day. Wouldn't there need to be a period where the line is suspended for passenger services so drivers can get rolling stock related route knowledge like stopping positions at each. I can't see how they could switch out the rolling stock overnight without having successful dry runs.
     
  22. hwl

    hwl Established Member

    Messages:
    4,855
    Joined:
    5 Feb 2012
    They have modified the software (awaiting testing), just that this is a lower priority change with the focus on getting CBTC in the core working as the highest.
     
    Last edited: 24 Jan 2019
  23. hwl

    hwl Established Member

    Messages:
    4,855
    Joined:
    5 Feb 2012
    GW-ATP is based on the Belgian TBL1 system. In 2006 SNCB concluded that TBL1 and ETCS wouldn't play happily with each other and TBL1 needed to be replaced with newer equipment TBL2/2+/3 to enable practical ETCS roll out.

    The RF environment in the tunnel is far worse than the open air so it might have been the case that the UK testing was done in open air and everything looked ok...

    As MarkyT has said the someone did a very good job convincing Heathrow to double up on all the ATP equipment to improve reliability when they were specing and building the tunnels!

    The design of the ATP equipment predates all the EMC rules
     
  24. zn1

    zn1 Member

    Messages:
    412
    Joined:
    3 Sep 2011
    whats that saying - the more you overdo the plumbing, the easier it is to block the drain...emu,loco control and safety systems are too computer dependent, ...the GW ATP system works, if it aint broken dont fix it.
     
  25. Brush 4

    Brush 4 Member

    Messages:
    107
    Joined:
    25 Nov 2018
    Modern computerised trains, and in other forms of transport do seem over complicated. If they fail there seems little a driver or signalman/woman can do to get things going again. It seems to be either go or stop, nothing in between, no temp fixes to get the train out of the way, or a signal overridden to get the line going asap.
     
  26. edwin_m

    edwin_m Veteran Member

    Messages:
    16,933
    Joined:
    21 Apr 2013
    Location:
    Nottingham
    Probably very difficult to get spares for it these days, still less extra equipment to extend it.
     
  27. hwl

    hwl Established Member

    Messages:
    4,855
    Joined:
    5 Feb 2012
    Yep, support was massively downgraded after SNCB started actively removing it (2012 - DfT had to twist their arm for IEP on board equipment) and not fitting it to new stock from 2006.
    It is a legacy product...
     
  28. MarkyT

    MarkyT Established Member

    Messages:
    3,860
    Joined:
    20 May 2012
    Location:
    Torbay
    Very much so. Also, in the UK application, the equipment was used in a much more comprehensive way than Infrabel/SNCB TBL1, where in combination with ancient 'Crocodile' ramps it provided only simple AWS-like warning and TPWS-like trainstop protection.
    https://en.wikipedia.org/wiki/Transmission_balise-locomotive
    The GW-ATP, by contrast, is a 'full supervision' system with custom speed curve supervision and additional earlier 'better aspect' update transponders where justified. The UK application will remain the only use of this equipment anywhere in the world after a similar system has been fully removed from part of the Hong Kong MTR, work that is currently underway. Infrabel/SNCB wanted to greatly expand train protection coverage and was faced with a choice of staying with the old tech or changing to a eurobalise-based implementation where an equivalent of the TPWS 'overspeed loop' could also be provided. The choice made makes migration to ETCS very much easier as the same transponders are used and the system can be emulated in the standard onboard ETCS computer and DMI screens of a modern train using the now largely standardised Level 1 'limited supervision' mode, and the standard balise reader hardware is used rather than needing an additional plug-in 'specific transmission module' to read legacy transponders.
     
    Last edited: 24 Jan 2019
  29. 43096

    43096 Established Member

    Messages:
    6,145
    Joined:
    23 Nov 2015
    All? You mean the Portsmouth line clowns who couldn’t/wouldn’t understand the explanation given and were stuck in their own selfish little world.
     
  30. jimm

    jimm Established Member

    Messages:
    4,925
    Joined:
    6 Apr 2012
    Sorry, but it is not correct to say 'it should have been completed by now' - it was decided a long time ago that the GW resignalling would be done in two phases - first with conventional lineside signals, which are what control trains now, to be followed by ETCS at a point in the early 2020s.

    There may have been indicative target dates for that but nothing has ever been set in stone when it comes to the timing of ETCS installation.

    It works? So why is it the cause of 28 per cent of all recorded technical incidents and 20 per cent of delay minutes on the GWR IET fleet then?

    The figures were given in the December issue of Modern Railways.
     
    Last edited: 27 Jan 2019
Thread Status:
Not open for further replies.

Share This Page