SOURCES at Crossrail are said to be warning that the new Elizabeth Line might not be open between Paddington and Liverpool Street before 2021, after fresh revelations about dynamic testing.

The central section of Crossrail uses automatic train operation, as well as ETCS between Paddington and Heathrow, and most trains will encounter two signalling interfaces on their journeys across London.

After problems were revealed in the summer last year, the original opening date of December 2018 then slipped to autumn 2019 and then to 2020.

The BBC has reported a source saying that dynamic testing – running trains under power through the central section – is ‘proving more difficult than was first thought. It all depends on how dynamic testing goes between now and the end of this year: the last quarter of this year will be a critical period.’

Work on stations has also been running behind schedule, with Paddington and Bond Street said to be still needing more work than the others.

Crossrail headways are intended to be no more than 2.5 minutes during the peaks between Whitechapel and Paddington.

When the contract for central section signalling was awarded to a consortium of Siemens and Invensys Rail in November 2012, Crossrail had said: ‘Crossrail will be adopting a Communications Based Train Control signalling system as it is technically and operationally proven and is successfully used by many metro systems around the world.’