Great Western Main Line upgrade


In the 2010s Network Rail modernised the Great Western Main Line, the South Wales Main Line, and other associated lines. The modernisation plans were announced at separate times but their implementation overlapped in the 2010s.
The work included electrification, resignalling, new rolling stock and station upgrades. The programme began in June 2010 and at that time was due to end in 2017. The project was completed in 2020, allowing electric services to run between London Paddington and Cardiff.
The project had several delays. Four sections were deferred indefinitely:
The Cardiff to Swansea electrification was cancelled in 2017.
Under the Intercity Express Programme, 21 electric Class 801 trains were ordered as replacements for the ageing InterCity 125 diesels. In May 2016 it was confirmed that the new trains would be built as 'bi-mode' Class 800s instead, meaning they can run on either diesel power or electric overhead wire.

Historical background

At the start of the 21st century, the Great Western Main Line and the Midland Main Line were the last of the major main line routes in the UK using diesel as the main source of locomotive power. When the announcement was made in July 2009 to electrify the Great Western, it represented the first big rail electrification project in the UK for 20 years. The South Wales Main Line section of the GWML was set to be the first electrified cross-country railway line in Wales.
The plan to upgrade the rolling stock on the Great Western was included in the IEP announced in 2007, a Department for Transport led initiative to replace the ageing fleet of InterCity 125 and InterCity 225 train sets then in use on much of the UK rail network.

Electrification

Status

Passenger timetables introduced electric running from Paddington to Didcot in January 2018, and to Swindon and as far west as Bristol Parkway in January 2019. The same month saw electric services between Reading and Newbury. Electric running to Newport commenced in December 2019 and to Cardiff in January 2020.
The Cardiff to Swansea electrification was formally abandoned in 2017. As of 2023, the electrification of Didcot to Oxford has yet to happen, after being delayed until track modification and station remodelling at Oxford.

Earlier work

Prior to 2009, the only electrified portion of the Great Western was between London Paddington and Airport Junction. This portion is equipped with a overhead system which was implemented in 1997 in readiness for the Heathrow Express service commencing in early 1998. Electrification was extended from Airport Junction to under the Crossrail scheme. Further electrification west of Maidenhead was announced by the DfT separately, though the work west of Airport Junction and west of Maidenhead is likely to be undertaken as one scheme.

July 2009 announcement

The UK government first considered electrifying the Great Western between London Paddington and Bristol Temple Meads in a first phase, then electrifying the rest of the line between and at a later date. However, in July 2009, the Department of Transport under the then Labour Government, announced that there would be a £1bn programme to electrify the whole of the Great Western from London to Swansea as well as to Bristol Temple Meads. The Labour government claimed that the investment would pay for itself over a 40-year period.
The scheme announced by the government on 23 July 2009 stated that "work will begin immediately on the electrification of the Great Western Main Line between London, Reading, Oxford, Newbury, Bristol, Cardiff and Swansea, to be completed within eight years". The proposed electrified route included:
  • the Great Western Main Line between London Paddington and Bristol Temple Meads via Swindon,, and ;
  • the South Wales Main Line from Swindon to Swansea via the Severn Tunnel;
  • the connecting line from to Bristol Temple Meads;
  • the section of the Cherwell Valley Line connecting Didcot Parkway with ; and
  • the section of the Reading to Taunton line connecting with.
Estimates showed that the Hitachi Super Express trains could reduce journey times from London Paddington to Swansea by 19minutes.
In an effort to minimise disruption during the electrification works, Network Rail developed new "factory engineering trains" to facilitate the process of installing overhead lines. There are three types of train: the first train to install pylons, followed by a train to hang the wires and finally a train to check the installation. The system was expected to be able to install of electrification in an eight-hour shift. The vehicles were supplied by German firm Windhoff.
In its initial survey, Network Rail identified 113 structures – mainly bridges and tunnels – which required modernisation. In subsequent surveys this increased to 137. The largest structure, the Severn Tunnel, has good clearances and is relatively easy to electrify.

Review and announcements after May 2010 general election

After the 2010 UK general election in May 2010, the Conservative–Liberal Democrat coalition placed all major government capital expenditure, including the Great Western electrification scheme on hold pending a return-on-investment review. In November 2010, Transport Secretary Philip Hammond gave the go-ahead for the lines from Oxford via Didcot to London and Newbury to London to be electrified in the next six years. Extension from Didcot to Swindon, Bath, Bristol and to South Wales would be dependent on a further assessment due in 2011 of the costs and implementation requirements of the IEP.
On 1 March 2011, Hammond announced that rail electrification from Didcot Parkway to Bristol Temple Meads and Cardiff Central would go ahead. The section linking Bristol Parkway and Bristol Temple Meads would also be electrified.
In March 2012, Amey plc was awarded a £700million contract to undertake the electrification works.
In July 2012, the UK Government announced that the final portion of the Great Western from Cardiff to Swansea would be electrified. In addition, as part of the Electric Spine project, the line between Reading and Basingstoke would also be electrified at OHL. The overhead electrification of the branches to Henley, Marlow and Windsor were also added to the scope of the project. However, the Marlow electrification has been postponed for the foreseeable future due to difficulties at Bourne End.
The new NR Series 1 overhead line equipment, designed and manufactured by Furrer+Frey, is a TSI compliant OLE design specified to allow multiple pantograph operation at operation and is being installed using Amey plc's High Output Plant System and other conventional techniques. This is designed to allow Adjacent Line Operation where works can be carried out while trains operate on adjacent tracks. The HOPS has five sections, each of which handles a different aspect of the installation – these can be coupled together to work as one unit, or separated to work independently. The train will be maintained at the High Output Operations Base in Swindon, on the site of former sidings. HOPS will mix and lay of concrete per night, and all equipment and personnel will arrive at the site on board.
The HOPS train was operational by 2014, but had not reached full productivity due to teething problems. By 2015, completion of the electrification project had been delayed, reportedly 1 year behind schedule, with completion expected in 2017. Costs of the electrification were reported to have tripled from an estimated £640M to £1.74bn.

Reviews after May 2015 general election

2015

In June 2015, the International Railway Journal reported: "Britain's secretary of state for transport, Mr Patrick McLoughlin has asked Sir Peter Hendy to review Network Rail's 2014–2019 capital investment programme, known as CP5, and report back in the autumn". The report stated that costs had tripled from the £874M original estimate to £2.8bn, and was £1.2bn higher than the estimate made a year ago. The main part of the programme will go ahead as planned and should be delivered by March 2019, but the Cardiff to Swansea section will be delayed, to some time between 2019 and 2024.
Revised dates for the completion of electrification work were published in early 2016, with electrification to Cardiff via Bristol Parkway, and the connection to Newbury planned by December 2018; the branch to Oxford from Didcot by June 2019; and the branch to Bristol Temple Meads from Wootton Bassett sometime between February 2019 and April 2020.

2016

In November 2016, the government announced that electrification work on the sections from Oxford to Didcot Parkway, Bristol Parkway to Bristol Temple Meads, Thingley Junction to Bath Spa and Bristol Temple Meads, and branches lines to Henley and Windsor had been indefinitely deferred. For Oxford and Bristol, the deferral was due to imminent resignalling and remodelling of the existing track layout.

2017

In July 2017, it was announced that the Cardiff-Swansea electrification project had been cancelled and that bi-mode trains would be used on the route.

Resignalling

The Great Western Main Line was equipped with colour light signalling common to the rest of the United Kingdom. At the time of the Ladbroke Grove rail crash, the ATP warning system was under trial. In response to that incident, it became a requirement for all First Great Western trains to be fitted with ATP.
When the Department for Transport wrote the specification for the new trains for the IEP in November 2007, it was stated that the Great Western Main Line would be upgraded to ERTMS/ETCS level 2 in-cab signalling and trackside infrastructure. Some or all of the resignalling work would be carried out alongside the electrification work. Signalling Solutions would resignal the 12miles from Paddington to, including the Airport branch, as part of the Crossrail project.