page_title: 21st-century modernisation of the Great Western main line
section_title: Electrification
hierarchical_section_title: 21st-century modernisation of the Great Western main line / Electrification
caption_attribution_description: English: Electrification work at Cardiff Central, Wales
context_page_description: Network Rail plans to spend £5 billion on modernising the Great Western main line, its South Wales branch and other associated lines. The modernisation plans were announced at separate times but their development time-scales overlap in the 2010s. The work includes electrification, resignalling, new rolling stock and station upgrades. According to Network Rail, the modernisation started in June 2010 and was due to end in 2017. As of December 2019, electrification was complete as far west as Cardiff Central, and also from Reading to Newbury.
  The project has been subject to repeated delays. In November 2016 the government announced that several major elements of the electrification programme would be indefinitely deferred because costs had tripled. The five sections that are delayed are:
  Oxford to Didcot Parkway
  Bristol Parkway to Bristol Temple Meads
  Thingley Junction, near Chippenham, to Bath Spa and Bristol Temple Meads
  Thames Valley branches to Henley and Windsor
  Swansea to Cardiff.
  Under the Intercity Express Programme, 21 electric Class 800 trains were ordered as replacements for the ageing InterCity 125 diesels.
caption: Electrification work at Cardiff Central on the South Wales Main Line
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