Translate the text from Welsh to English.



 
Ar 23 Mawrth atebais gwestiwn brys yn y Siambr am y methiant pŵer ym mlwch signalau Gorsaf Ganolog Caerdydd ar 22 Mawrth, a effeithiodd ar yr holl drenau i Gaerdydd.


Fe wnes i ddatgan ar y pryd, ac mae’n bwysig pwysleisio hynny o’r newydd, bod y math hwn o fethiant pŵer, mewn amgylchiadau o’r fath, yn anarferol. Dywedais hefyd mai Network Rail sy’n gyfrifol am ymdrin â’r materion yn ymwneud â’r methiant pŵer. Nid oes gan Lywodraeth Cynulliad Cymru unrhyw gyfrifoldeb datganoledig dros Network Rail.


Serch hynny, nid wyf am weld cymudwyr yn cael eu rhwystro rhag mynd i’w gwaith, ac mae’n amlwg y bod y methiant pŵer wedi amharu’n sylweddol ar bobl yn ardal Caerdydd ar 22 Mawrth.


Bydd Network Rail a Threnau Arriva Cymru yn cyhoeddi adroddiad ffurfiol llawn i’r digwyddiad cyn bo hir.


Yn y cyfamser, roeddwn wedi cytuno i roi rhagor o wybodaeth i Aelodau’r Cynulliad. Daeth yr wybodaeth ychwanegol ganlynol i law oddi wrth Network Rail:


Cafwyd yr adroddiad cyntaf bod y system signalau wedi methu ym Mlwch Signalau Caerdydd Canolog am 07:07\. Wedi hynny, daeth cadarnhad fod blychau signalau Cyffordd y Mynydd Bychan a’r Barri wedi colli pŵer hefyd.


Roedd yr adolygiad cychwynnol yn awgrymu mai ymchwydd pŵer sylweddol oedd achos posibl y methiant. Fodd bynnag, ar ôl i bersonél Western Power ymchwilio ymhellach i’r mater, canfuwyd mai’r hyn a achosodd y digwyddiad oedd methiant cebl oedd yn cysylltu’r generadur ‘wrth gefn’ â’r system signalau yng Nghaerdydd.


Canfuwyd drwy ymchwilio ymhellach bod y nam wedi digwydd am fod y pwyntiau terfynu yn y cebl wedi gorboethi. O ganlyniad, roedd y cerrynt a lifai drwy’r cebl wedi cynyddu, gan chwythu ffiws ac achosi methiant y prif gyflenwad pŵer i’r cyfarpar signalau. Roedd y generadur wrth gefn wedi cychwyn wedyn fel y dylasai, ond bu cylched fer oherwydd y cebl difrodedig, ac arweiniodd hynny at fethiant y generadur wrth gefn. Mae’r math hwn o fethiant yn anarferol dros ben ac nid oedd wedi digwydd o’r blaen.


Yn syth ar ôl clywed am golli’r pŵer i’r cyfarpar signalau, aethpwyd ati i gaffael generadur arall o Orsaf Bwmpio Sudbrook (Twnnel Hafren). Roedd y signalau wedi’u hadfer yn llawn erbyn 10:00, rhyw deirawr ar ôl i’r methiant gael ei gofnodi gyntaf.


Cynhaliwyd adolygiad o’r digwyddiad gan y diwydiant ddydd Mercher 23 Mawrth, gyda chynrychiolwyr o’r cwmnïau cludo teithwyr a nwyddau ac o Network Rail. Yn ystod yr adolygiad talwyd sylw arbennig i effeithiolrwydd y diwydiant wrth ymateb i’r digwyddiad ac wrth adfer y gwasanaeth trenau wedyn.


Er ein bod yn cydnabod yn llwyr bod y methiant hwn yn seilwaith y rheilffyrdd wedi bod yn andwyol iawn ac wedi amharu’n fawr iawn ar drefniadau teithio, ystyrir bod yr ymateb dilynol a’r broses o adfer y gwasanaeth wedi bod yn effeithiol ar y cyfan. Yn nodweddiadol, byddai digwyddiad o’r maint hwn wedi cael effaith ar yr holl drenau weddill y dydd, ond yn yr achos hwn, cyn gynted ag yr adferwyd y signalau aeth y trenau’n ôl i lefel resymol o brydlondeb. Llwyddwyd i gyflawni hyn drwy ddefnyddio dulliau rheoli rhagweithiol wrth adfer y gwasanaethau. Erbyn canol dydd, roedd yr oedi gweddilliol yn y system wedi lleihau’n sylweddol ac erbyn canol y prynhawn roedd prydlondeb y trenau, yn ôl y Mesuriad Perfformiad Cyhoeddus (PPM), wedi dychwelyd i’w lefel arferol. Serch hynny, cafwyd 5,000 munud o oedi o ganlyniad i’r digwyddiad hwn, a bu’n rhaid gohirio 223 trên yn llwyr neu’n rhannol.


Yn y tymor byr i ganolig, bydd Network Rail yn cynnal archwiliad fforensig o’r cyfarpar signalau a’r cyflenwad pŵer ym mlwch signalau Caerdydd er mwyn pennu union natur y diffygion. Bwriedir cynnal adolygiad o’r protocolau archwilio a chynnal a chadw cyfarpar hefyd.


Yn y tymor hirach, bydd Network Rail yn cyflwyno rhaglen gwerth £220 miliwn i foderneiddio’r signalau yn ardal Caerdydd, gan symud y gweithrediadau signalau i ganolfan rheoli newydd De Cymru yn Nhreganna. Mae Llywodraeth Cynulliad Cymru’n ariannu rhai elfennau o’r rhaglen hon, gan gynnwys cyfleusterau newydd ar gyfer troi trenau yn ôl yn y Barri, Caerffili a Phontypridd. Mae cam datblygu’r rhaglen hon eisoes wedi’i gwblhau i raddau helaeth a disgwylir ar hyn o bryd y bydd y broses gomisiynu’n mynd rhagddi rhwng 2013 a 2015\.


Rwyf o’r farn bod ateb Network Rail wedi  bod yn ddigon cynhwysfawr o ystyried bod y digwyddiad yn un mor ddiweddar. Gwn fod Trenau Arriva Cymru hefyd yn adolygu eu gweithdrefnau cyfathrebu ac yn diwygio’u prosesau ar gyfer delio â digwyddiadau mawr eraill a allai amharu ar wasanaethau yn y dyfodol.


Bydd Llywodraeth y Cynulliad yn adolygu’r adroddiad ffurfiol  am y digwyddiad hwn yn fwy manwl pan fydd yn ei chyrraedd maes o law.


O ran effaith y digwyddiad hwn ar yr economi ehangach, mae’n anodd rhoi amcangyfrif meintiol dibynadwy. Yn amlwg, roedd digwyddiad wedi amharu yn sylweddol ar batrymau gwaith. Er hynny, wrth geisio pennu’r effaith gyffredinol, dylid ystyried y ffaith mai cyfan gymharol fach o gymudwyr sy’n teithio ar y trên, hyd yn oed yn Ne\-ddwyrain Cymru, ac y byddai llawer o’r gweithgareddau ar y diwrnod hwnnw wedi’u gohirio yn hytrach na’u canslo’n gyfan gwbl.


O ystyried y niferoedd yr effeithiwyd arnynt a hyd cyfartalog yr oedi, ac o ymgorffori’r amcangyfrifon bras ynghylch gwerth posibl yr allbwn a gollwyd, mae’n debyg bod y methiant pŵer hwn wedi costio oddeutu £1 miliwn i’r economi.







Translation:


 
On 23 March I answered an urgent question in the Chamber about the power failure at Cardiff Central Station signal box on 22 March that affected all train services into Cardiff.


I stated at the time, and it is important to re\-emphasise, that this type of power failure in these circumstances is unusual. I also said that the issues relating to the failure are within the remit of Network Rail. The Welsh Assembly Government has no devolved responsibility for Network Rail.


Nevertheless, I would not want to see commuters unable to go about their business, and clearly there was major disruption to the network in the Cardiff area on Tuesday 22 March.


Network Rail and Arriva Trains Wales will be producing a full, formal report into the incident. This will be available shortly.


In the meantime, I agreed to provide further information to Assembly Members. The following additional information has been received from Network Rail:


The first report that the signalling system had failed was received from Cardiff Central Signal Box at 07:07\. Subsequently, Heath Junction and Barry signal boxes confirmed that they too had lost power.


An initial review suggested the cause may have been a significant power surge. However, further investigations involving Western Power personnel were able to discount this and by early afternoon it became apparent that the root cause was the failure of a cable connecting the ‘stand\-by’ generator to the signalling system at Cardiff.


Subsequent investigations showed that the fault resulted in the termination points in the cable over\-heating. As a consequence of this, the amount of current drawn increased which blew a fuse and caused the cessation of the mains power supply to the signalling equipment. As it should, the stand\-by generator then started but the damaged cable caused a short circuit which resulted in the failure of the back\-up generator. This type of failure is highly unusual and had not been experienced before.


Immediately after the loss of power to the signalling equipment was first reported, a replacement generator was procured from Sudbrook Pumping Station (Severn Tunnel). Full signalling was restored by 10:00, approximately three hours after the failure was first reported.


An industry review of the incident took place on Wednesday 23rd March. This involved representatives of passenger and freight operators and Network Rail. During this review particular attention was paid to the effectiveness of the industry’s response to the incident and the subsequent recovery of the train service.


While it is fully acknowledged that this was a hugely damaging and disruptive failure of the railway infrastructure, the subsequent response and service recovery is considered to have been largely effective. Typically, an incident of this magnitude will have significant knock\-on effects throughout the rest of the day. In this instance, as soon as full signalling was restored, the industry was quick to recover to a reasonable level of punctuality. This was achieved by pro\-active management of the reinstatement of services. By midday the amount of residual delay in the system had reduced significantly and by mid afternoon the punctuality, as measured by PPM, had returned to normal levels. In total, however, this incident caused 5,000 minutes of train delay and resulted in 223 full or part train cancellations.


In the short to medium term Network Rail will be conducting a forensic examination of the signalling and power supply equipment at Cardiff signal box to determine the exact nature of the faults experienced. A review into inspection and maintenance protocols will also be undertaken.


In the longer term, Network Rail is embarking on a £220m programme which will modernise the signalling in the Cardiff area. This will see the migration of signalling operations to the new South Wales Control Centre at Canton. The Welsh Assembly Government is funding elements of this programme including new turn\-back facilities at Barry, Caerphilly and Pontypridd. The programme is already well into the development phase and commissioning is currently expected to run from 2013 to 2015\.


I believe that Network Rail has provided a comprehensive reply so far for such a recent incident. I am aware that Arriva Trains Wales is also reviewing its communication procedures and amending its processes for dealing with future large scale incidents of service disruption.


The Assembly Government will review the formal report of this incident in more detail, when it arrives in due course.


In terms of the effect of the incident on the wider economy, it is difficult to provide a reliable quantitative estimate. Clearly there was widespread disruption to work patterns. However, in judging the overall impact, account also needs to be taken of the fact that rail travel accounts for a relatively small share of commuting, even in South East Wales, and that in many cases, activities may have been delayed rather than abandoned altogether.


Taking account of the numbers affected, likely average lengths of delays, and incorporating broad estimates of the potential value of lost output, it would suggest that the economic cost of the disruption was probably of the order of £1 million.