London's £19bn Crossrail project has begun running test trains through the centre of the capital as plans ramp up ahead of next year's opening..

The new Elizabeth Line is now operating four trains an hour as part of safety testing, a "crucial milestone" in the bumpy and drawn-out story of the project, stretching from Reading and Heathrow to Abbey Wood in south east London.

The Trial Running programme is underway, with integrated test trains aiming to demonstrate that the Elizabeth Line is safe and reliable, and will meet the capacity and performance requirements needed to move into the final stage.

Crossrail says it will be steadily ramping up the numbers of trains running through the 42km of tunnels built below London, and on the existing railway network, so the rail link can be run as close as possible to an operational timetable.

Crossrail - PA

Crossrail - PA

Mark Wild, Crossrail Chief Executive, said: “We have now started the Trial Running of trains on the Elizabeth line and this is an incredibly significant moment. It marks the moment when our focus shifts to commissioning of the new railway and it puts us firmly on the path to Trial Operations and ultimately the opening of the Elizabeth line.

“I want to thank everyone who has worked so hard over many years to get us to this point. There have been real challenges along the way but the start of Trial Running is an important milestone for the Elizabeth line and for London.”

The launch of trail running is a welcome one after years of delays to the project, which is billions of pounds over budget.

Crossrail - PA

Crossrail - PA

When it opens in the first half of 2022, the rail link will aim to provide fast, frequent services direct to Canary Wharf, central London and Heathrow, terminating in Abbey Wood.

Sadiq Khan, the Mayor of London, said: “Safely delivering the Elizabeth line as soon as possible is one of my top priorities, so I’m really pleased that Trial Running is now underway.

"The whole Crossrail team are doing all they can to get the railway open and ensure London and the wider South East can enjoy its many benefits sooner rather than later.”

Throughout the Trial Running programme, operations and maintenance staff and train drivers will play an integral role with the Romford Route Control Centre (RCC), the hub where they will signal all trains in the tunnel. Maintenance teams will be available to keep the railway running, as well as responding to any operational incidents across the network.

Crossrail is also making progress with the new central section stations and has recently transferred Tottenham Court Road Elizabeth line station to TfL, which means the station can be fully integrated with the operational network ahead of the Elizabeth line opening.

The Elizabeth Line - PA

The Elizabeth Line - PA

Woolwich, along with Liverpool Street and Paddington, will be the next stations to transfer to TfL.

Declan McGeeney, Director of UK Infrastructure, Laing O’Rourke, said: “I am immensely proud of our team for what they have achieved and how they have overcome the challenges of the past 12 months to get to this point.

"Their commitment to the project has been absolute and they have worked in close partnership with Crossrail and London Underground to create what is a truly impressive new station that will improve the journeys of millions of people for many decades to come.”