Three tower cranes are being installed at the New Dunedin Hospital inpatient building site as the project enters its vertical construction phase.

Health Minister Simeon Brown announced the milestone, saying the cranes will lift structural steel and major components over the next two and a half years. The crane bases have been installed over the past two months.

About 40 workers are currently on site daily, with numbers expected to rise to 80 in coming weeks. The outpatient building remains on schedule to open later this year.