Costs are rising on the bumper Bank station upgrade to boost capacity at the busy City hub, according to new Transport for London (TfL) papers.
In its latest investment programme report, the capital's transport body said the final cost of the Bank station capacity and systems integration upgrade was now expected to come in over budget at £655m.
TfL first said final costs for the revamp were expected to be over budget in December – at £642m, £19m higher than the £623m originally forecast.
At the time it also confirmed the work was running late, and is now expected to be wrapped up in 2022 as opposed to the initial late 2021 forecast.
But now, costs are running higher still with the new final cost estimate of £655m. TfL said the revised increase in cost was due to the systems integration project which had been extended, resulting in "increased main contractor costs, internal labour and third party/PFI costs".
TfL added that the expected final cost for capacity upgrade works remains under pressure as new risks were being identified, and a review is still ongoing to assess "the full extent of the cost challenge", including any potential options to trim back costs.
The work is part of a critical project to improve capacity at Bank and create more space for customers.
Bank and Monument stations form the third busiest interchange on the London Underground network, and are used by more than 52m passengers each year.
TfL is boosting capacity by 40 per cent at the City's key station, as well as providing a quicker interchange for customers, and a new Northern Line southbound tunnel for more space.
Two new lifts and 12 new escalators are being installed, and step-free access will be introduced on the Northern Line and DLR platforms.
A new Bank station entrance for the Waterloo & City Line is also being built, though that too is running late and is now expected to open in late 2018 – pushing back an already revised opening date of March.
The entrance was first expected to open right back at the start of the year in January.
There have been "a number of issues" with the manufacture and installation of fire doors there, leading to delays. TfL has said it is working with the contractor to ensure the station will open on time.