Installing barriers, safety nets and other restrictions at notorious suicide hotspots like bridges, cliffs and railways could cut the number of suicides at these sites by more than 90 percent, according to research published on Wednesday.

In a large study covering known hotspots around the world, researchers found that other measures such as putting up signs and crisis telephones to encourage people to seek help also appear to significantly reduce the number of deaths.

Suicide is currently the second leading cause of death among 15- to 29 year-olds, according to World Health Organization (WHO) data. Across all age groups worldwide, around 800,000 people kill themselves each year.

Some of the world's most notorious suicide sites include London's "Tube" subway system, the Eiffel Tower in Paris, the Golden Gate Bridge in San Francisco and the Prince Edward Viaduct in Toronto.

Jane Pirkis at the University of Melbourne in Australia, who led this research and published in The Lancet Psychiatry journal, said it showed how certain intervention measures can "buy time to allow an individual to reconsider their actions and allow others the opportunity to intervene".

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Pirkis' team conducted a systematic review and meta-analysis of all studies examining the effectiveness of three suicide prevention measures - restricting access to the means, encouraging help-seeking and increasing the likelihood of intervention by a third party.

They then used modeling to estimate the effect of each intervention in isolation or in combination with others.

Thee results, using data from 18 studies in all, showed that the interventions significantly reduced the number of suicides at the sites in question - with deaths falling from an average of 5.8 suicides a year before actions were taken, to an average of 2.4 deaths annually afterwards.

Measures aimed at blocking access to places where people go to kill themselves led to 91 percent fewer suicides a year when used in combination with other interventions, and a 93 percent reduction when used alone.

Experts say suicide hotspots are accessible, usually public sites frequently used as a location and which gain a "reputation for suicide". These can include bridges, tall buildings, cliffs, railway tracks and isolated places rural car parks and woodland.

"Suicide attempts at these sites are often fatal and attract high profile media attention which can lead to copycat acts," Pirkis said.