The cost of the London Overground Gospel Oak to Barking electrification project has climbed to £171.9m, after delays due to incorrect design and late delivery of materials.
In papers for a meeting of Transport for London's (TfL) programmes and investment committee at the end of June, the transport body warned the final cost for the project is now "likely to be in considerable excess" of the original £130m budget.
Today, Network Rail told City A.M. the revised cost of the project is now £171.9m, saying the original budget had been £133.2m.
A spokesperson said: "The additional funding is being met through efficiencies across Network Rail's project portfolio."
TfL has said it is committed to a fixed sum of £25m "irrespective of the eventual cost of the project", and the final cost will be a matter for the Department for Transport (DfT) and Network Rail.
However, it will receive compensation for the loss of fare revenue and consequent direct costs of delays, such as replacement bus services. These are estimated to be between £3m and £10m depending on the final programme of works agreed.
Network Rail said its revised figure for the upgrade included compensation to TfL and freight for cancellation of services.
A DfT spokesperson said:
Our upgrade programme will double the space for passengers on the Gospel Oak to Barking line, with new four-carriage trains replacing the existing two-carriage services, as well as improving local air quality.
We expect the project to be completed early next year and the cost will be covered from within existing budgets.
Work on the upgrade began in June last year, with TfL originally planning for electrification of the line to finish by the beginning of last month, but it was revealed in February that work had not been finished in time, with more closures needed.
Last month Network Rail said the works will now be completed by January 2018, with two longer closures proposed for Sunday 17 September to Sunday 22 October, and Monday 27 November to Sunday 14 January.
Delays cropped up on the project after a number of the structures carrying the overhead lines were incorrectly designed and couldn't be installed at the planned locations. Further delays were caused by late delivery of materials and structures.
Jonathan Fox, TfL’s director of London Rail, said: “We have been working closely with Network Rail to ensure their remaining work to electrify the Gospel Oak to Barking line is finished as soon as possible to minimise the disruption to our customers and to avoid delay to the introduction of new electric trains next year.
"Discussions continue about the level of compensation needed to cover the costs of this extended closure. Any compensation would be to provide refunds to customers forced to make more expensive journeys, the provision of extensive rail replacement bus services and communicating service changes to our customers.”
Meanwhile, Barking and Dagenham council has written to Network Rail demanding there are no further delays on the project.
Leader of the council, Darren Rodwell, said in the letter to Network Rail boss Peter Hendy: "Residents and businesses in Barking and Dagenham have already endured eight months of disruption on the line and it’s vital that they are not unduly inconvenienced again."