The cost of renewing the Rotherhithe Tunnel could be as high as £178m, TfL believes, money the authority currently does not have.
The estimate, an increase on the previously floated £120m figure, is “subject to funding being available.”
TfL has previously warned that the tunnel could face further closures, as it only has the money to do the barest of essential maintenance work on the crossing to make sure it is “safe and operable.”
In response to Lib Dem Assembly Member, Caroline Pidgeon, Mayor Sadiq Khan said: “The renewal of the Rotherhithe Tunnel is currently progressing through concept design.
“At this early stage in project development, Transport for London (TfL) estimates that costs will be in the range of £116m to £178m, subject to funding being available.
“TfL plans to complete the concept design work later in 2020.
“An updated estimate will then be produced, prior to the appointment of a contractor in 2021 to progress detailed design. In addition to the project activities, TfL will continue regular maintenance and progress any short-term minor renewal work to ensure the tunnel remains safe and operable.”
A ferry option between Rotherhithe and Canary Wharf was paused earlier this year because TfL does not have the budget for it.
In response to a further question about the ferry from Ms Pidgeon, Mayor Khan said: “The work on developing proposals for a Rotherhithe to Canary Wharf ferry service is currently paused until we have greater clarity over Transport for London’s (TfL’s) long-term funding position.”
He added: “I can assure you that the impact of any long-term closures of the Rotherhithe Tunnel on local residents and businesses will be a key consideration in the further development of this work.”