The stand-by crew, which was based at the city's central ambulance station in York Pl on those nights, has been cut after a study revealed the three ambulances rostered on were in use only about two-thirds of the time over the two nights, St John regional operations manager Doug Third said.
"We were totally underutilising the night fleet."
The analysis was done for St John Otago regional management team by the St John planning and development team in Auckland.
It also showed the stand-by ambulance was sometimes sent to low priority jobs that could have waited longer and been done by one of the duty ambulances.
The stand-by crew was being called out less often over the past few years and recently might be called out just once each night, Mr Third said.
Before July 1, two duty ambulances and a stand-by crew operated in Dunedin on Fridays and Saturdays from 7pm.
One fully-crewed ambulance based in Mosgiel covered that town.
From July 1, two duty ambulances would cover Dunedin city on Friday and Saturday nights and on-call paramedics would be more heavily relied on for back-up in emergencies.
An extra crew had been on stand-by on Friday and Saturday nights for "about 100 years" and cutting it was not a decision made lightly, Mr Third said.
But the data backed it up and local management felt there was an opportunity to better use the two duty ambulances.
"We are not concerned about service capability."
The stand-by ambulance was manned by a paid ambulance officer working overtime and a volunteer, so no jobs would be lost.
A union spokesman for ambulance officers, Peter Costello, from the Amalgamated Workers Union (Southern), said he had no concern, at this stage.
He had not had any complaints from ambulance officers about the cutback.
