Great Western railway electrification, UK: testing and commissioning

The UK’s £3 billion Great Western railway electrification programme was completed in 2019, enabling electric trains to run from London to south Wales. This paper describes the complex testing and commissioning process required to bring the new overhead line system into service. Starting with testing the new overhead line equipment design on a dedicated 21 km test track in Leicestershire, the testing and commissioning then had to be undertaken in stages as the electrification work progressed, integrated with the railway and its legal and regulatory framework as a whole.