The works, which have begun with changing the layout of EA to help patients get faster and safer care, are due to be completed by March 2026.
The programme is designed to reduce waiting times and provide better spaces for treatment with fewer patients cared for in temporary areas.
Within the ED, a larger and better UTC will be integrated with other A&E services.
A new paediatric clinical decision unit, co-located with the recently opened new paediatric A&E, will open in autumn 2025 to provide better facilities for emergency treatment of children and complement the £4m major refurbishment of the Acorn children's ward completed earlier this year.
Further improvements include upgrades to maternity and postnatal wards, comprising more single patient rooms on wards and better ventilation and air conditioning for over 250 beds by the end of this year.