Extra beds and additional staff are on standby at the Royal Victoria Hospital's accident and emergency unit in a bid to cope with a possible spike in patient demand over the weekend.
The Belfast Trust confirmed the contingency plan and "additional capacity" had been created if patient levels rise – days after scenes of chaos were witnessed in the department.
But staff at the Royal Victoria A&E unit say they fear scenes of overcrowding could return to the department.
On Wednesday staff and patients, who waited up to 12 hours for treatment, described the hospital conditions as "mayhem".
At one stage 42 people were waiting on trolleys, with many left in corridors for up to 12 hours until they were treated. Concerns had been raised about the impact on emergency departments as this will be the second weekend A&E units in Lagan Valley and in Downpatrick will be closed.
But a Department of Health spokeswoman said: "Initial analysis of the impact on other emergency departments of the closure of the Downe and Lagan Valley emergency departments showed that this did not have a significant impact."
Meanwhile, Ray Rafferty from health union Unison said staff at the RVH A&E were preparing for further pressure.
"I think the overall impressionthat the staff have is it will be quiet for a day or two and will be back to 'ground zero' either at the weekend or the start of next week," he said.