The opening of the Northern Line Extension in south London is to be pushed back by nine months, New Civil Engineer understands.

The line, which will link Kennington and Battersea, will now be opened in September 2021 rather than the originally planned December 2020 date, multiple sources have revealed.

The introduction of services on the new line is being “realigned” to coincide with the opening of the Bank Station upgrade allowing for additional capacity on the line. The new opening date would therefore be pushed back until after the planned three-month, partial closure of the Northern Line in 2021.

A Transport for London investment programme report published in December last year revealed that the final works at Bank Station were set to be completed in 2022, a year later than planned.

Consequently, a source close to the project said the opening date for the Northern Line Extension was being shifted.

“In isolation the Northern Line Extension project is still on time and working towards a December 2020 finish,” the source said. “However, instead of doing a big bells and whistles unveiling then it will be realigned with the completion of works at Bank station.

“Works at Bank are scheduled to finish in June 2021 and then the opening of the entire Northern Line Extension will coincide with the opening of the new Bank station in the autumn of 2021.”

Northern line extension map

In a recently published board meeting, TfL said the forecast completion year of 2020 for the Northern Line Extension was being “reviewed as the designs for Battersea Power Station’s over site development and the Tube station have evolved”.

A TfL spokesperson said: “We are committed to completing the Northern Line Extension. TfL is working collaboratively with Battersea Power Station Development Company and we are making good progress - major tunnelling finished last year and the new and existing Northern line tunnels were connected for the first time. Track is being laid in both tunnels and the platforms at the new stations are currently being installed ahead of the further station fit-out next year.”

Tunnelling for the 3.2km long line was originally due to start in summer 2016 but was pushed back six months as modifications were made to the work schedule. It was then due to start in March but slipped to April as readying the TBMs took longer than expected.

Controversy over the cost of the line has also mired the project’s history. In 2016, London Underground said it was in discussions with the developer of Battersea Power Station over funding for changes to the design of the Malaysian-backed redevelopment scheme and the design of the underground station box.

TfL has not released the overall projected cost for building the line, citing it as commercially sensitivity. However TfL has confirmed that £643M has been spent on the project to date.

A Ferrovial, Agroman and Laing O’Rourke joint venture selected by London Underground in 2014 is carrying out the works to design and build the new line which will have two new stations at Battersea and Nine Elms.

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