Progress on the £31bn Crossrail 2 project has stuttered, after Transport for London (TfL) said today an independent financing review sought by the government will not be completed until the autumn.
It means hopes for a public consultation getting underway early this year have been dashed.
TfL's director of City Planning, Alex Williams told the London Assembly Transport Committee that work had started on an independent funding and financing review announced by the government to look at how costs could be reduced further.
He said that will report back "in the autumn".
The government has backed the south east rail project, but transport secretary Chris Grayling previously set the Crossrail 2 team the task of London funding half the project during construction as opposed to over the life of the scheme, which meant they had to submit a revised business and funding plan.
Deputy mayor for transport Val Shawcross said today the Crossrail 2 team had "jumped every hurdle we've been asked to jump and quickly, and well, I think".
However, she said the government had come back to the revised funding case saying:
We want an independent financial review to look at whether or not you could reduce the costs and how viable what's proposed is. So, it seems to be a long, slow process, but it's still moving in the right direction.
The plan had been to get a public consultation underway early this year, but the Department for Transport will only consider a public consultation after the independent review has deemed the funding plans a success. Grayling has said the public needs to get "an affordable scheme that is fair to the UK taxpayer".
With the independent review now not expected to report back until the autumn, further pressure is being put on the wider timescale to submit a hybrid bill to parliament in 2020.
"We would like to be able to consult, make sure that we've got all of the route protected - safeguarded - and that Londoners know what we're working on," Shawcross said today. "However, this is a joint project with the government so we're unable to release all of the detail without government's consent."
Darren Caplan, chief executive of the Railway Industry Association, said: "The Railway Industry Association urges the financial review of Crossrail 2 to be undertaken as swiftly as possible, so the project can proceed as planned on the timescale originally envisaged. Without doing so, it will be more difficult to integrate Crossrail 2 with other major infrastructure investments like HS2 - meaning we are less able to reduce congestion for passengers on our rail network."