Six months after winning a share of the Mayor of London’s £100m cycling initiative, the authority has fine-tuned its plans for the scheme and found costs may soar to more than £41m.
TfL has so far agreed to fund the project to the tune of £34m – already £4m more than initially expected.
But a report by Kingston Council officers, due to be discussed by councillors next week, said a joint review with TfL “may require that in some areas the scope of projects will be revised”.
It added: “The mini-Holland programme has been refined over time to form a coherent package, including gaining a better understanding of the costs and delivery challenges.”
However, the report adds such a funding gap could be managed during the delivery of the programme.
The review of the project’s business case is expected to take four months.
Councillor Richard Hudson, cabinet member for capital projects, said: “This is quite a normal process, but we need to be sure that Kingston Council isn’t going to be lumbered with a £7m bill.
“There is always a risk with any infrastructure project that there may be incremental costs.
“TfL are committed to this and I can’t see them not fully funding it, but it’s a risk.”
Opposition leader Councillor Liz Green, who was leader of the council at the time Kingston won the mini-Holland bid, said: “We were told to bid up to £40m.
“We’re not going to lose the £34m as long as it’s progressed properly, and I don’t think that the borough will pick up any extra cost for it.
“They are working up a project plan and it will change over time as different issues come forward.”
But Andrew Judge, a Labour councillor from neighbouring Merton, which lost out on the TfL cash, said: “It’s important in local government that you keep to your spending limits.
“£34m is an awful lot of money. I’m sure they could do an enormous amount.”
Ben Plowden, from TfL, said: “The allocation from TfL was based on the costs submitted by the borough.
“However, following further work, Kingston has now identified some additional costs, which takes the scheme over this agreed budget.
“We are working alongside them to help reduce these costs so we can ensure the programme remains on target to deliver these transformational schemes.”
Tim Lennon, from Richmond Cycling Campaign, said: “You would hope, certainly, that Kingston got the numbers right in the first place. I could imagine that it can be more expensive to do than they originally thought.”
The report will be discussed at the infrastructure, projects and contracts committee on Thursday, September 11, at 7.30 pm.