It is expected to relieve pressure on existing east-west London Underground lines such as the Central and District lines, as well as the Jubilee line extension and the Heathrow branch of the Piccadilly line.
Pengoperasian ini diharapkan dapat mengurangi beban jalur-jalur London Underground timur-barat yang sudah ada seperti Central dan District Line, serta perpanjangan Jubilee Line dan cabang Piccadilly Line di Heathrow.