Preparations are due to start next week for the £420 million revamp of the Royal Sussex County Hospital in Brighton.
The work is planned even though the government has not yet signed off the business case for the project.
The project team want to be able to hit the ground running if the Treasury approves the funding.
Hospital trust chief executive Matthew Kershaw is expected to present a report to his fellow board directors today (Monday 28 April) setting out the next steps.
A written report has been circulated to the Brighton and Sussex University Hospitals NHS Trust board in advance of the meeting.
His report says: “Preparatory works on site will start on Tuesday 6 May and these initial works will run throughout May.
“The works involve some gas diversions and changes to the traffic flow to and from the Eastern Road in front of the Barry and Jubilee buildings to prepare for the Front Car Park modular build.
“Information on these changes will be publicised widely for patients, visitors and staff.”
His report also says: “The preparations setting out the work required for the Final Business Case has further progressed as we await a decision from Her Majesty’s Treasury on the Outline Business Case.
“This work will commence as soon as a positive decision is made.
“Meanwhile we have also continued working on discharging our planning conditions with Brighton and Hove City Council in advance of work starting on the three approved decant schemes.”
The decant schemes involve moving staff and patients out of the buildings that are due to be demolished in readiness for the huge project.
Mr Kershaw wrote: “Further updates about the programme of works which will happen over the next six months will be shared over the coming weeks.”
Brighton Kemptown MP Simon Kirby said: “The decision is still on a knife edge. I will be campaigning and lobbying right up to when a decision is made. Brighton needs a new hospital.
“With the news that the hospital are planning to commence with preparatory works on site, it is now even more imperative than ever that we get a positive decision on funding from HM Treasury.
“I will continue to keep up the pressure to ensure that Brighton gets the hospital that patients, staff and residents deserve.”
“I have been campaigning on this issue for some time and this news will make me redouble my efforts as this is such an important issue.
“I have informed the Treasury of this latest development and that we are all ready to go here in Brighton if they make the correct decision.”