Crossrail (to be known as the Elizabeth line) is a 73-mile (117-kilometre) new railway line under development in England.

Crossing London from west to east, at each end of its central core the line will divide into two branches: in the west to Reading or stations at Heathrow Airport, and in the east to Abbey Wood or Shenfield. In May 2015, a section of one of the eastern branches, between Liverpool Street and Shenfield, was transferred to TfL Rail; this precursor service also took control of Heathrow Connect in May 2018.

The project was approved in 2007, and construction work began in 2009 on the central section and connections to existing lines that will become part of the route. A main feature is 13 miles (21 km) of twin tunnels below the city running from Paddington to Stratford and Canary Wharf.