The partnership behind the £500 million redevelopment of Birmingham's New Street Station will not know until July next year whether the ambitious project will definitely go ahead.
Complex funding streams and the need to convince a Government department and the regional development agency of the scheme's viability makes it unlikely that the finances and final permission will be in place before next summer, Network Rail has confirmed.
Martin Chambers, project director for the New Street scheme, said he was fully confident the Rail Regulator and the Department for Transport would approve their portion of the funding.
"It is high on the agenda. A priority item with the regulator," Mr Chambers added.
The partners behind the New Street scheme are Network Rail, Birmingham City Council, Advantage West Midlands and Warners, the owners of the Pallasades shopping centre.
Business case submissions were filed with the Department for Transport and Advantage West Midlands in May.
A third plank of the application process involves obtaining approval from the Office of the Rail Regulator.
Mr Chambers said an out-line planning application to redevelop the six-acre New Street site would be submitted to Birmingham City Council next month. He expects several months of discussion with the council to follow before approval in principle is given.
Work will then begin on detailed designs for the new station concourse.
The length of time taken to process the scheme was not unusual given New Street's complexity, Mr Chambers added.
He said: "We are talking about six acres in the heart of the city centre. It is a very large and important site.
"Lots of major regeneration projects have complicated funding streams, but it will all come together in the end.
"It is important to remember that this is not just about delivering a new station. It is also about the regeneration of significant part of the city centre, an area bounded by the Bullring and Corporation Street."
He confirmed that talks about the future of the Pallasades were under way with Warners.
"They only bought the shopping centre last November and they are starting to think about what they want for the Pallasades going forward. They are well and truly engaged with us and we hope to formalise something later this year," Mr Chambers added.