Passenger services on London's delayed and over budget Crossrail project are on track to begin by the end of June, Transport for London has announced.
The railway will initially operate between Abbey Wood and Paddington through new tunnels under central London. It will be known as the Elizabeth line once services begin.
Crossrail was planned to open in full from Reading, Berkshire, to Shenfield, Essex, in December 2018, and was set a budget of £14.8 billion in 2010.
But it has been hit by numerous problems including construction delays and difficulties installing complex signalling systems.
Transport for London said the first phase of trial operations are coming to an end.
The next phase will involve thousands of staff from TfL, Network Rail and other organisations taking part in exercises on the railway to test timetables and trial scenarios such as evacuations.
"This is an extremely exciting year for us and for London as we get ever closer to opening the Elizabeth line and welcoming customers from Abbey Wood to Paddington," said Andy Byford, Transport for London’s Commissioner.
"The launch of this much needed and transformational addition to the transport network will be central to the recovery for London and the UK.
"Customers will experience a new way of travelling – with brand new, spacious step-free stations and new connections across the capital and beyond.
"There will be no better symbol of London’s renaissance from the pandemic," he added.
Mark Wild, Crossrail Chief Executive, said: "The Elizabeth line is on track to open in the first half of 2022 as we continue to make progress on completing the works necessary to start passenger services in the central section of the railway, from Paddington to Abbey Wood.
I’d like to thank everyone for their continued hard work and we look forward to beginning the next phase of Trial Operations exercises."
The total cost of the project has been estimated to be £18.9 billion, including £5.1 billion from the Government.
TfL said London will "ultimately fund the majority of the cost".