Western Australia's biggest move of child patients from one hospital to another is set to run throughout most of Sunday.
Almost 100 children are being shifted from Princess Margaret Hospital (PMH) in Subiaco to the new Perth Children's Hospital (PCH) in Nedlands in one day.
Health Minister Roger Cook said it was a complex logistical exercise.
"We'll be undertaking the single biggest move of young patients in the state's history, utilizing a convoy of patients, taking them down to the new PCH," he said.
"[It will involve] police, main roads, disaster preparedness units and of course 650 staff, making sure that we can make this move as safe as possible."
Mr Cook said it was a big day for health care in the state.
St John Ambulance will provide 13 ambulances for the move, and will be joined by two specialist Newborn Emergency Transport Service ambulances.
The Health Department's executive director of nursing services Katie McKenzie said ambulances would be leaving PMH at five-minute intervals for the four-kilometre trip.
"Each five-minute slot is spread across multiple wards, and the critically unwell children will be captured in that, so we have a safe and structured arrival at Perth Children's Hospital," she said.
"It is so very exciting."
One-day move optimal: Cook
The Minister said the staged opening of PCH had gone "very well" to date, including day operations and outpatient clinics.
Mr Cook said the plan to move patients in one day was based on experiences in other states, as well as being informed by the opening of Fiona Stanley Hospital in Perth's southern suburbs.
"The experts have advised that it's best to do the move in one hit," he said.
Police will provide six motorcycle units to control traffic on Thomas Street during the transfer, the Government said.
In addition, Main Roads will sequence traffic lights to provide "green corridors" and will monitor traffic control on Hamilton Street, Roberts Road, Thomas Street and Hospital Avenue.
