The project’s operational testing phase got under way over the weekend, marking the final stage of work to introduce services between Paddington and Abbey Wood in tunnels under the capital.

More than 150 scenarios will be trialled over the coming months, including exercises to make sure all station systems and procedures work effectively and staff can respond to any incidents, such as signal failures.

Trial running of trains through the tunnels has already been under way since May. In the new year, a series of more complex exercises will include evacuations of trains and stations using thousands of staff and volunteers.

The final step will then see a period of ‘shadow running’ during which timetabled services are to be operated ahead of the Elizabeth Line’s opening.

“Everyone is working hard to make sure we can open the Elizabeth Line safely and reliably in the first half of 2022,” said Transport for London’s commissioner Andy Byford. “The trial operations phase will see staff really get to grips with all aspects of this complex and transformational railway to ensure we are ready to welcome customers next year.”

Crossrail is currently running around four years behind schedule and an estimated 30% over its original budget. Eight of the ten central section stations are now under the responsibility of Transport for London with contractors beginning to demobilise across the sites.

It is expected to take several months to complete the operational testing phase; only then will a specific opening date for the new railway be announced.

(Photograph: Transport for London)