A new €40m emergency dep- artment (ED) has been app-roved for Beaumont Hospital.
The existing department is one of the busiest in the country.
The move will pacify Independent Alliance minister Finian McGrath, who had demanded a new department in return for supporting the minority government.
He said it was "fantastic news for the staff and patients" of Beaumont.
"I'm delighted it's being progressed," the Dublin Bay North TD said last night.
In a letter seen by the Herald, the HSE advised Beaumont Hospital that €100,000 will be made available next year for "design team fees".
"We should be ready to roll on construction in 2019," said Mr McGrath.
The existing ED provides services to more than 50,000 patients a year, including many from hospitals throughout the country who need neurosurgical assessment.
It has been plagued by problems in recent years as staff struggle to cope with the ever-increasing number of patients on trolleys.
Last winter, patient organisations described the overcrowding situation in Beaumont as "akin to a warzone".
The Irish Nurses and Midwives Organisation (INMO) has asked for the department to go "off call" on a number of occasions in recent years due to overcrowding.
On the day of last week's Budget, Beaumont was the most overcrowded hospital in Dublin, with 25 people waiting for a bed. It is understood the new ED will be three times the size of the existing facility.
The hospital has expressed a desire to develop the new ED on the current site, but the HSE said the design team would also consider other potential sites.
The budget for the project will be decided once the initial design work is complete, but sources say it will be about €40m.
Mr McGrath said he was "delighted" that years of campaigning were about to reach a conclusion.
The announcement will ensure he continues to back Leo Varadkar's government. The minister said his focus would now move to securing funding for a dedicated cystic fibrosis unit at Beaumont.