As we doubtless know, we’re currently in Stage One, the TfL Rail branded service between Liverpool Street and Shenfield which is progressively seeing the older mainline trains replaced with new Elizabeth line trains as they roll off the production line in Derby.
Stage Two comes this May when TfL Rail takes over the existing Heathrow Connect service, ahead of becoming part of the Elizabeth line in December 2019. However, it was warned yesterday that software problems could delay the takeover until later in the year.
The big launch is this coming December, when the central tunnels open. However, due to the works that will still be ongoing, Elizabeth line services will terminate in the new low-level platforms at Paddington, and then carry on to Heathrow via the main line station.
The TfL Rail service between Shenfield and Liverpool Street will be essentially unchanged.
A few months later, in May 2019, Stage Four comes into action, linking Shenfield to Paddington directly through the central London tunnels, although some trains will still terminate at the mainline station as well.
Finally in December 2019 the full Elizabeth line tube map will be finally completed, with services running out to Reading, and Heathrow Terminal 5. Also, the broken connection at Paddington will be closed.