The future Crossrail route will retain the use of most of this track, except the portion between Liverpool Street and , where trains will use new tunnels to connect to the central section of the route. The western branches operate over part of the Great Western Main Line and the Heathrow tunnel between Paddington and Heathrow for , and entirely over the Great Western Main Line between Paddington and Reading for . As of May 2020, the typical Monday–Saturday off-peak service pattern is:  The eastern branch of TfL Rail operates with a fleet of new trains. The Class 315 trains will continue to be maintained at the existing Ilford depot, but the Class 345 trains will be maintained at Old Oak Common and Ilford depots. TfL Rail inherited five units from Heathrow Connect when it took over operations on 20 May 2018. These trains will be used to operate the existing half-hourly (2tph) service to Heathrow. Class 345 trains will run on the Heathrow branch from summer 2020. On 26 September 2019, TfL Rail announced that it would take over the Paddington to Reading stopping services on 15 December 2019, using Class 345 trains in place of the Class 387 and Class 165 trains used by Great Western Railway. Before that, on 25 November 2019 six GWR services a day started to operate using Class 345 trains, operated by TfL, to get drivers ready and stock in place for the main 15 December switch over.