Crossrail is a completed railway project centred around London. It provides a high-frequency hybrid commuter rail and rapid transit system, known as the Elizabeth line, that crosses the capital from suburbs on the west to east and connects two major railway lines terminating in London: the Great Western Main Line and the Great Eastern Main Line. The project was approved in 2007, and construction began in 2009 on the central section and connections to existing lines that became part of the route, which has been named the Elizabeth line in honour of Queen Elizabeth II who opened the line on 17 May 2022 during her Platinum Jubilee. The central section of the line between Paddington and Abbey Wood opened on 24 May 2022, with 12 trains per hour running in each direction through the core section in Central London.

The Elizabeth line is a high-frequency hybrid urban–suburban rail service in London and its suburbs. It runs services on dedicated infrastructure in central London from the Great Western Main Line west of Paddington station to Abbey Wood and via Whitechapel to the Great Eastern Main Line near Stratford; along the Great Western Main Line to Reading and Heathrow Airport in the west; and along the Great Eastern Main Line to Shenfield in the east. The service is named after Queen Elizabeth II, who officially opened the line on 17 May 2022 during her Platinum Jubilee year; passenger services started on 24 May 2022. Despite being named under the same system as London Underground lines, and having sections which are underground, the Elizabeth line is not classified as a London Underground line.