Researchers estimate 14 lives could have been saved if barriers had not been removed for a time from Grafton Bridge in inner Auckland.

A team of researchers from the University of Otago in Christchurch and Yale University in the United States examined how the removal and subsequent return of safety barriers on the historic landmark affected the number of suicides.

Safety barriers to prevent suicide by jumping were removed in 1996 after having been in place for 60 years.

After they were removed, there was a five-fold increase in the number and rate of suicides from the bridge.

These increases led to a decision to reinstall barriers.

Since they were put back in 2003, using an improved design, there have been no suicides.

The researchers estimated that had barriers not been removed, 14 lives could have been saved.

Associate Professor Annette Beautrais, who conducted the research, said that the finding added to an increasing body of evidence that the most effective form of prevention at bridge-jumping sites is installing safety barriers.

"This evidence justifies preventive interventions at sites that become identified for suicide, and suggests that these approaches are now moving towards becoming best practice in suicide prevention," she said.

The research was funded by the Health Research Council of New Zealand.